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 History and conservation of wild and cultivated plant diversity in Uganda: forest species and banana varieties as case studies

 History and conservation of wild and cultivated plant diversity in Uganda: forest species and



全 文 :History and conservation of wild and cultivated plant diversity in
Uganda: Forest species and banana varieties as case studies
Alan C. Hamilton a, *, Deborah Karamura b, Esezah Kakudidi c
a Kunming Institute of Botany, Chinese Academy of Sciences, Heilongtan, Kunming 650204, Peoples Republic of China
b Bioversity International Uganda Office, PO Box 24384, Kampala, Uganda
c Department of Botany, Makerere University, PO Box 7062, Kampala, Uganda
a r t i c l e i n f o
Article history:
Received 3 November 2015
Received in revised form
3 November 2015
Accepted 1 December 2015
Available online 5 April 2016
Keywords:
Ecosystem-based plant conservation
Pollen diagrams
Indigenous knowledge
Resource governance
a b s t r a c t
The history of wild and cultivated plant diversity in Uganda is reviewed, taking forest species and ba-
nanas as examples. Palynological research into past human influences on forests is reassessed. The ev-
idence suggests that crops were first introduced into the country at about 1000 BCE, farming
communities practicing slash and burn agriculture started to significantly influence the floristic
composition of forests during the 1st millennium BCE and there was a major episode of forest reduction
at about 1000 CE related to socio-economic change. Bananas were probably introduced in the early
centuries CE. The colonial era from 1894 saw the introduction of new concepts of land ownership and the
establishment of forest reserves and agricultural stations. Forests and banana diversity are currently
under threat, Uganda having a very high rate of deforestation and endemic banana varieties proving
susceptible to introduced pests and diseases. It is suggested that, under these circumstances, conser-
vationists take an opportunistic approach to field engagement, making use of favourable local conditions
as they arise. Partnerships should be sought with elements of society concerned with sustainable use,
provision of ecosystem services and cultural survival to widen the social base of plant conservation.
International organisations involved in conservation of plant genetic resources and wild plant species
should collaborate with one another to develop the conceptual basis of plant conservation, to make it
more relevant to countries like Uganda.
Copyright © 2016 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by
Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-
NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1. Introduction
This paper presents an overview of the history of wild and culti-
vated plant diversity in Uganda, providing a platform for advancing
suggestions for its conservation. Indigenous plant diversity is under
great threat in Uganda today, with conservation hampered by many
constraints. Uganda shares features with many other countries and
hopefully the suggestions offered will be useful for them too.
The Green Revolution of the 1950s and 1960s dramatically
increased the yields of some major crops, helping to forestall an
anticipated global shortage of food. The introduction of genes
resistant to pests and diseases from traditional varieties of crops
was critical to this development, which, in turn, drew attention to
the rapid rate of decline in the number of such varieties. It is esti-
mated that 75% of the genetic diversity of agricultural crops was
lost during the 20th Century (FAO, 1998; Hawkes et al., 2001). The
International Board for Plant Genetic Resources (IBPGR) was
founded in 1974 to coordinate an international programme to
conserve plant genetic resources, concentrating initially on the
landraces of major crops and the expansion of gene banks, notably
seed banks and field collections (FAO, 1992).
The scope of the conservation movement concerned with plant
genetic resources has widened over the years, coming to embrace
wild relatives of crops, minor agricultural crops and other uses of
plants additional to food (Prescott-Allen and Prescott-Allen, 1988).
More emphasis is being placed on in situ conservation. Conse-
quently, this branch of plant conservation has moved closer to the
other school of plant conservation that has been developing over
the same period, founded on concern about loss of species of wild
plants, and associated with tools such as Red Data Books, protected
areas and ex situ collections (Given, 1994; Hamilton and Hamilton,
* Corresponding author. 128 Busbridge Lane, Godalming, Surrey GU7 1QJ, UK.
E-mail address: alanchamilton@btinternet.com (A.C. Hamilton).
Peer review under responsibility of Editorial Office of Plant Diversity.
Contents lists available at ScienceDirect
Plant Diversity
journal homepage: http: / /www.keaipubl ishing.com/en/ journals /plant-diversi ty /
ht tp: / / journal .k ib.ac.cn
http://dx.doi.org/10.1016/j.pld.2016.04.001
2468-2659/Copyright © 2016 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This
is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Plant Diversity 38 (2016) 23e44
2006). It is estimated that 20% of the worlds 380,000 species of
plants is threatened with extinction (Kew, 2012). The number of
species of actual or potential conservation concern (from the
perspective of the plant genetic resource movement) has thus been
dramatically expanded, for instance now theoretically including
the 50,000e70,000 species of plants estimated to be medicinal
(Lange, 1997; Schippmann et al., 2006).
Greater specificity is provided here by paying special attention
to species living in one particular type of plant community (rain-
forest) and to one particular crop (the banana). Forest species and
forests (as collective entities) provide a wide range of useful
products and ecosystem services in Uganda. The latter include
regulatory services (such as climatic amelioration and soil stabili-
zation), provisioning services (such as delivery of water supplies)
and cultural services (having significant symbolic value) (Hamilton,
1984; Ray, 1991). Uganda has the highest per capita consumption of
bananas in the world and is a secondary centre of genetic diversity
for the crop (Daniells and Karamura, 2013e2014; Gold et al., 2002;
Karamura et al., 2010; Karamura and Mgenzi, 2004). Bananas in
Uganda are eaten steamed, roasted and raw, as well as brewed for
beer. Matooke, a dish prepared by steaming and mashing cooking
bananas, is the staple food of millions of people (Vernacular terms
used here are from Luganda, an indigenous language.).
Uganda is a medium-sized country (area 236,000 km2) strad-
dling the equator in the heart of Africa. It lies within the Great Lakes
region of the western part of East Africa, with Lake Victoria to the
south and Lakes Albert and Edward in the Albertine Rift to the west
(Fig. 1). The population (36 million in 2012) is growing rapidly
(3.27% p.a.) and becoming more urbanized (growth rate 4.4% p.a.).
Despite urbanization, the primary means of livelihood for most
people remains farming (73% of households in 2006e9), com-
plemented by extensive use of wild plants for construction, crafts,
fuel, medicines and other purposes. Much of the economy is cen-
trally related to plants. The gross domestic product (GDP) was US
$1404 in 2012 with most people financially very poor. Uganda is a
culturally diverse country, having 42 indigenous languages classi-
fiable into 4 major language groups. Many types of polity were
present prior to the establishment of the Uganda Protectorate by
Britain in 1894. English and Swahili are the official languages.
Uganda is a signatory to the International Treaty on Plant Ge-
netic Resources for Food and Agriculture (2004), the Convention on
Biodiversity (1992) and the Global Strategy for Plant Conservation
(2002). Official conservation tools include protected areas, ex situ
collections and special legislative protection for some species.
2. Plant diversity, plant resources and agriculture in Uganda
Uganda offers an exceptionally wide range of habitats available
for human exploitation (Schoenbrun, 1998). Rainforest is the nat-
ural vegetation in higher rainfall areas (about 20% of the land area),
which lie mostly towards the west and north. Lowland rainforest
grades into montane forest at higher altitudes, with woodland,
bushland and other types of savannah in drier parts (Langdale-
Brown et al., 1964). Forest clearance over the years has resulted in
once continuous stretches of forest being reduced to scattered
remnants embedded within matrices of cropland, secondary
vegetation, swamps and urban areas. Much of the country outside
forests and settlements is frequently burnt and grazed by livestock.
Small-scale farmland covered 43.5% of the land area in 2005, large-
scale farmland 4.8% and built-up areas 4.8% (FAO, 2010b).
The indigenous flora contains about 5000 species of higher
plants (Davis et al., 1986). Tree floras report many species as having
uses (Eggeling,1952; Hamilton, 1991; Katende et al., 1995) and local
inventories of medicinal plants can yield extensive lists (Adia et al.,
2014; Galabuzi et al., 2015; Katuura et al., 2007; Lye et al., 2008;
Tabuti, 2008; Tabuti et al., 2003). Intensive studies sometimes
reveal uses for unsuspected species, suggesting that much ethno-
botanical knowledge remains undocumented. The small forest
trees Rytigynia kigeziensis Verdc. in Bwindi Impenetrable Forest and
Belanophora coffeoides Hook. f. in Mpanga Forest were apparently
unknown to scientists to have specific uses before research
revealed that the first yielded a vital medicine used as a dewormer
(“without this we will die”) (Cunningham, 1996) and the second to
have been harvested methodically (carefully differentiated from
several similar-looking species) for construction purposes (Taylor
et al., 2008).
Many systems of plant use and management exist, embracing
both cultivated and wild plants, and varying according to location,
ethnicity, household wealth, and ownership of land and livestock. A
farming household in the Central Regionmight, for instance, rely on
a home garden (lusuku) to supply its staple food of cooking ba-
nanas, outfields (emisiri) for sweet potatoes, forest (ekibira) for
firewood, taller grassland for fodder (essubi), swamp (ekisenyi) for
papyrus (used in making mats) and sandy valley areas for the many
products obtained from the wild date palm, including termite-
resistant poles. Wild plants are often collected to sell. Unsustain-
able harvesting of wild plants is frequently reported, the most
obvious problem being the cutting of trees to supply the Kampala
market with fuel (firewood and charcoal). At least 90% of people in
Uganda rely on woodfuel, 90% of trees cut for products being har-
vested for this purpose (Kabogozza, 2011).
Tasks in the supply and management of plant resources tend to
be gender-related, with men more involved where money is to be
made or when the end-product is alcoholic (Karamura et al.,
2004). The collection of firewood for home use is overwhelmingly
bywomen and children, butmen dominate the commercial trade in
charcoal. The lusuku, which serves mainly to supply subsistence
products to the household, is almost exclusively the preserve of
women (Karamura et al., 2004). Women also take the lead in the
provision of food for the family and in maintaining its health, and
are responsible for most craft-making, so are the main holders of
indigenous knowledge of plants. A continuing interest in indige-
nous botanical knowledge is apparent from the retention of a di-
versity of local varieties of crops by some farmers (Mulumba et al.,
2004; Zawedde et al., 2014) and the widespread use of herbal
medicine (Cunningham,1993; Hamilton and Aumeeruddy-Thomas,
2013; Lwanga, 1992). Anecdotal reports suggest that an interest in
indigenous botanical knowledge is declining among the young,
especially those from richer families.
The lusuku (commonly translated as ‘banana garden’ in English)
is a type of indigenous agroforestry system that forms a key
component of farms in the Central Region. It typically covers 22% of
the 0.7 ha of cultivated land on an average farm (area 1.4 ha)
(Edmeades et al., 2007). Bananas form a key component, but many
other species can be present, having a variety of life forms, uses,
degrees of domestication and intensities of management. Types of
plants can include: (1) large trees, such as Albizia coriariaWelw. ex
Oliv. (omugavu, timber, wood used to smoke barkcloth); (2)
medium-sized trees, such as Spathodea campanulata P. Beauv.
(kifabakazi, decorative and medicinal); (3) small trees and bushes,
such as Coffea canephora Pierre ex A. Froehner (mumwanyi, pro-
ducing coffee beans for the market); annual crops, such as kidney
bean Phaseolus vulgaris L. (ebijanjaalo); (4) perennial crops, such as
cocoyam Colocasia esculenta (L.) Schott (ejjuuni); (5) herbaceous
plants, some semi-cultivated, such as spinach Amaranthus dubius
Mart. ex Thell. (doodo) and (6) climbing and scrambling plants, such
as Dioscorea yams (balugu, kyetutumula, etc.). The lusuku can have
horizontal as well as vertical structure, for instance with types of
bananas containing the B genome typically placed around the pe-
riphery and newly acquired varieties of bananas planted near the
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4424
homestead, where the soil tends to be more fertile and perfor-
mance easier to monitor (Karamura et al., 2004).
Bananas are classified scientifically into genome groups (based
on the contributions of genes from two wild diploid species) and
on ploidy. One genome (designated A) is from Musa acuminata
Colla, native to western Melanesia and Southeast Asia, and the
other (B) from Musa balbisiana Colla, native to Southeast Asia and
China (Davey et al., 2013; Perrier et al., 2011). The earliest record
of cultivation of bananas globally is from New Guinea (cultivated
by at least 5000e4500 BCE) (Denham et al., 2003) Although the
banana is an introduced crop in Africa, there are two genome
groups that are indigenous to central or west equatorial Africa
and that have diversified extensively. These are the East African
Highland genome group (AAA), geographically centred on
Uganda, and the Plantain genome group (AAB), centred in the
rainforest zone of the Congo basin and represented in Uganda by
roasting bananas known as gonja. The East African Highland
genome group is conventionally labelled AAA-AE to distinguish it
from other AAA groups. The total number of AAA-EA varieties in
Africa has been estimated at ca. 60 and of Plantains ca. 120 (De
Langhe et al., 1994-5). Conservation of the germplasm of the
AAA-EA genome group is a particular concern for Uganda. A
number of other genome groups (AA, AAA, AB and ABB), collec-
tively known as the ‘Indian Ocean complex’, are thought to have
been present in the coastal fringes of East Africa for some cen-
turies, but did not penetrate into the Great Lakes area before
1900 (De Langhe et al., 1994-5).
Surveys of banana diversity on farms in Uganda have revealed
the presence of a very large number of locally named varieties of
AAA-EA bananas, though few of Plantain (possibly under-recorded)
(Table 1) (Edmeades and Karamura, 2007; Gold et al., 2002). High
levels of varietal diversity among AAA-EA bananas were recorded
at both farm and village levels, the mean number of varieties per
farm being 7.0 and 12.3 (in the two surveys respectively) and va-
rieties per village 23 and 26. Some AAA-EA varieties were found to
be present on many farms, but others narrowly confined. Thirty-
five percent of the varieties recorded in one survey were present
at only one or two sites (Gold et al., 2002). Local people have their
own ways of classifying bananas, using traits such as the size and
shape of various parts of the plant, the texture, flavour and colour of
the food, and agronomic and commercial attributes (Karamura
et al., 2011). Some varieties receive recognition for their
Fig. 1. Locality map of Uganda.
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 25
medicinal or aesthetic properties, or have other special uses or
meanings (Gold et al., 2002; Nantale et al., 2008).
The AAA-EA genome group does not normally reproduce
sexually. Therefore, its varietal diversification and geographical
dissemination are attributed to other processes, including somatic
mutation, the excision of suckers carrying the mutations by people,
the planting of these suckers at new sites and (at some stage)
recognition that the types are distinctive and worthy of being
maintained (and named) in their own right (Karamura et al., 2010).
Conservationists interested in finding ways to conserve the on-
farm diversity of AAA-EA bananas need to understand how peo-
ple interact with them. Research has revealed that new varieties
introduced onto farms are typically sourced from family or friends,
living in the same or other villages, and given freely without charge
(Karamura and Mgenzi, 2004; Karamura et al., 2004). Criteria
considered when selecting new varieties can include end-use at-
tributes, resistance to pests and diseases, and suitability for specific
environments. Special efforts can be made to retain rare varieties,
even those especially susceptible to pests and diseases, have weak
rooting systems or have limited ability to sucker (Mulumba et al.,
2004). Measures include manuring, dusting the soil with ash,
loosening the soil around the stools (to increase the infiltration of
water into the soil) and continuous relocation (to reduce losses
through weevils and nematodes).
Taxonomists working in Uganda have tried to develop a stand-
ardised system of nomenclature for bananas, assigning a unique
name to each cultivar, thus bridging across languages and dialects
and hopefully eliminating synonymy (Edmeades and Karamura,
2007; Karamura et al., 2011). This makes it easier to compare ba-
nana growing in different parts of the country and devise national
strategies for the conservation of banana germplasm. The applica-
tion of standard taxonomic approaches (based mainly on
morphological features) has shown that AAA-EA bananas can be
grouped into five major categories (‘clone sets’) (Karamura and
Pickersgill, 1999), which, in turn, can be distinguished from ba-
nanas belonging to other genome groups (AB, AAB, etc.) (Karamura
and Mgenzi, 2004). The names given to the clone sets are Mbidde,
Musakala, Nakabululu, Nakitembe and Nfuuka. Of these,Mbidde and
Nakitembe are particularly distinctive from a standard taxonomic
perspective, which, it has been suggested, is because they have
been recognised and deliberately propagated for exceptionally long
periods of time. However, DNA analysis has shown that the various
Table 1
Types of bananas found on farms in Uganda according to two surveys.
Genome group or type Genomea Survey 1 (1993e1994)b Survey 2 (2004e2005)b Main uses Origin and history
Frequency
(% farms)
Proportion
of plantsc
Commoner
varieties
(% farms)
Number of
varieties
identified
Commoner
varieties (% farms)
Tetraploid hybrids AAAA
AAAB
AABB
4 Kawanda (4)d All bred outside Uganda.
Triploid hybrid AAA 1 Received from IPGRI.e
Gros Michel AAA 63 2 Bogoya (60) 2 Bogoya (41)f Dessert Gros Michel (¼ Bugoya)
introduced to Entebbe
Botanical Gardens after
1900; first noted on
Martinique (Caribbean)
in 1830s.
Kamaramasengeg AAB 92 12 Ndiizi (85)h 1 Ndiizi (61) Dessert Ndiizi introduced Entebbe
Botanical Gardens after
1900; place of origin unknown.
Ney Poovan AB Kisubi (40) 1 Kisubi (28) Brewing Kusubi introduced Entebbe
Botanical Gardens; probably
originated in India.
Pisang Awak ABB 67 8 Kayinja (63) 2 Musa (16)
Kayinja (14)
Brewing Pisang Awak and Bluggoe
probably brought to East
African coast from India
by Arab traders possibly
ca. 500 CE; probably
introduced into Uganda
by British in colonial times.
Bluggoe ABB 2 Kivuvu (14)
Kidhozi (9)
Multiuse
East African Highland AAA-EA 100 76 Nakabululu (58)
Mbwazirume (50)
Nakitembe (49)
Musakala (42)
Enyeru (39)
82i Nakyetengu (58)
Nakubululu (44)
Mbwazirume (37)
Musakala (33)
Kibuzi (33)
Cooking
(to make
matooke)
and brewing
Long present in Great Lakes
region of East Africa (many
endemic varieties); probably
brought to East African coast
by Indonesians (possibly later
than ancestor of Plantains).
Plantain AAB 43 2 Gonja (43) 3j Gonja (14) Roasting Long present in Central and
West Africa (many endemic
varieties); probably brought
to East African coast by Indonesians.
a The wild species contributing the genomes are M. acuminata Colla (AA diploid) and M. balbisiana Colla (BB diploid).
b Survey 1 (Gold et al., 2002); Survey 2 (Edmeades and Karamura, 2007).
c This is the percentage of plants assigned to genome groups or types, averaged across farms.
d Farmers call all these tetraploid hybrids Kawanda.
e This triploid hybrid (Yangambi Km5) was received from the International Plant Genetic Research Institute (IPGRI) (Kikulwe et al., 2007).
f The second Gros Michel type encountered in the survey was Bogoya Omumyufu (Red Bugoya), found on 3% of farms.
g Taxonomy after (Onyango et al., 2011).
h Assignment of Ndiizi to the Kamaramesenge subgroup is after (Pillay et al., 2003).
i The number of varieties of AAA-EA bananas noted in the other survey (Survey 1) was 120.
j The 3 types recognised in Survey 2 were Gonja, Majaga and Manjaya. Most Ugandans do not distinguish between different varieties of Plantains.
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4426
varieties included in theMbidde clone set are not all closely related
genetically, their distinctiveness being rather due to mutations at a
single locus giving them the ability to synthesise tannins and an-
thocyanins (and thus produce astringent sap, the quality appealing
to beer brewers) (Tugume et al., 2002). Among the other four clone
sets, Musakala is particularly distinct genetically, but Nfuuka,
Nakitembe and Nakabululu are closely related. A characteristic of
the Nfuuka clone set is high susceptibility to morphological change
(hence the name in Luganda, which means ‘I change’).
3. Origin and history of plant diversity in Uganda to 1900
3.1. Forests and forest plants before agriculture
Comparison of DNA sequences has demonstrated that some
African forest-dwelling species of Afromomum, Begonia and Eryth-
rophleum originated in forest refugia that were isolated from one
another during arid periods of the Quaternary (Duminil et al., 2015;
Harris et al., 2000; Sosef, 1994). Speciation in these cases occurred
relatively recently by geological standards, estimated to have been
during the last tens of thousands to hundreds of thousands of years.
Other DNA analyses, carried out on groups of related species in the
families Annonaceae and Rhamnaceae, have revealed that their last
common ancestors lived 4e28 and 19e33 million years ago
respectively (Richardson et al., 2004).
The diversity of plant germplasm found at any place today is the
product of many processes, among which climatic change is typi-
cally amajor contributor. Some of themain climatic events believed
to have been influential in moulding the composition of the mod-
ern forest flora of Uganda are listed on Table 2. Greater detail is
given towards the present, since relatively minor climatic events
become increasingly important for determining modern distribu-
tions as the present approaches. Tropical Africa had a much wetter
climate than now at the beginning of the Miocene Period
(23 My BP), with rainforest very extensive. Progressive desiccation
through the Miocene and Pliocene (23e2.6 Myr BP) led to forest
retreat and the extinction of species, contributing to the relative
poverty of the modern flora of tropical Africa relative to South
America and Asia (deMenocal, 2014; Plana, 2004). A consequence
of the progressively drying climate of tropical Africa was a rise to
prominence of grasses in the flora, with savannah expanding at the
expense of forest. Grasses have been present in the flora of tropical
Africa since the Palaeocene (66e56 Myr BP), but only began to
increase in abundance after 16 Myr BP and more so from 8 Myr
(Jacobs, 2004), with extensive areas of grassland, as found today in
Serengeti (Tanzania), only existing after 3 Myr BP (deMenocal,
2014).
The spread of savannah at the expense of rainforest was sig-
nificant for the evolution of the human, whose ancestors adopted
an upright stance and started to live more on the ground and less in
the trees from about 4 Myr BP (Tattersall, 2014). Human anteced-
ents and their bipedal cousins shared the expanding savannah with
a number of other animals, such as bovids, possibly influencing
them in their courses of evolution, which, in turn, could have had
knock-on influences on the evolution of some plants. The
controlled use of fire by human ancestors, probably accomplished
prior to 400,000 BP, is likely to have led to more fires in the
savannah, increasing the relative abundance of more fire-resistant
plants.
The Quaternary Period (2.6 Myr to the present) has been a time
of major climatic fluctuations in many parts of the world, a series of
glaciations in temperate regions being generally marked by rela-
tively cool arid times in tropical Africa (Rossignol-Strick, 1983;
Rossignol-Strick et al., 1982). A consequence for Africa has been
the repeated contraction and expansion of forest, resulting in the
isolation of populations of some forest species in two ormore forest
Table 2
Some major climatic events since 23 Myr BP that have moulded the floristic diversity of modern forests in Uganda.
Time perioda Climate Rainforest
Last few centuriesb Many climatic fluctuations, some
geographically widespread, others
apparently more local.
The influence of climatic events on
rainforest in Uganda is difficult to
discern against strong human influence
on the vegetation.
From 4000 to 3500 BPc to the present Drier than previously (but still wet
compared with ice age aridity).
There was a transition to drier forest
types at ~4000e3500 BP in Uganda,
experienced at all altitudes.
From 12,500 to 10,000 BPd to the present Warmer and much wetter than
previously.
The extent of forest expanded greatly in
Uganda at ~12,500e10,000 BP.
From 2.6 Myr BPe to the present Marked climatic fluctuations in Africa,
especially after 800,000 BP.
There were major contractions and
expansions of forest in tropical Africa
driven by the fluctuating climate.
Differentiation and extinction of
populations of forest species.
23e2.6 Myr BPf Climate initially much wetter than now
across tropical Africa, becoming
progressively drier.
Forest was initially more extensive than
now in tropical Africa, then retreating
with species being lost.
a Dates are in years before present (BP), those based largely on radiocarbon dating (younger than ~40,000 BP) being in 14C years before 1950 CE. Dates given in calendar years
(BCE or CE) elsewhere in this paper are in calendar years, transposed from 14C years where necessary (Reimer et al., 2009).
b The most detailed climatic records for the last ~1000 years reveal fluctuations in climate of short to medium term duration (decades to centuries) (Ryves et al., 2011;
Ssemmanda et al., 2005). A dry phase at ~1750e1850 CE has been detected widely across East Africa. Similar short-term climatic fluctuations are likely to have occurred
at all times.
c A mid-Holocene shift to a drier climate has been widely recorded across equatorial and northern Africa, with the abruptness of the transition debated (McGlynn et al.,
2013; Tierney et al., 2011). The date of ~4000e3500 BP given here (equivalent to ~2050e1850 BCE in calendar years) is one quoted in regional reviews (Hamilton, 1982,
1992; Jolly et al., 1997; Kiage and Liu, 2006). A notable feature seen in many pollen diagrams from Uganda is a rise in the very well dispersed pollen type Podocarpus
(produced by the gymnosperm genera Afrocarpus and Podocarpus).
d There is much evidence for a major transition from a relatively cool dry climate prevailing across equatorial Africa during the last global ice age (peaking at 18,000 BP) to
warmer andmuchwetter conditions thereafter (the postglacial). The date of this transition given here is based on assessments of the pollen evidence for East Africa as a whole
or parts thereof (Hamilton, 1982, 1992; Jolly et al., 1997; Kiage and Liu, 2006).
e This is the Quaternary Period, marked by a series of ice ages in temperate parts of the world.
f Several publications discuss climatic change during this period and its effects on the flora (Hamilton and Taylor, 1991; Harris et al., 2000; Jacobs, 2004; Plana, 2004; Sosef,
1994).
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 27
remnants during the drier periods. Such populations have some-
times become evolutionarily differentiated, speciation sometimes
resulting (Diamond and Hamilton, 1980; Hamilton, 1988; Plana,
2004). The peak of the last global ice age (18,000 BP) saw very
little forest remaining in Uganda (Hamilton, 1982) with Lakes Vic-
toria and Albert at much lower levels than today (Beuning et al.,
1997; Kendall, 1969). The transition to the warmer and wetter
postglacial climate occurred over the period 12,500e10,000 BP,
sincewhen the climate has been relativelywet by ice age standards,
though somewhat drier from 4000 to 3500 BP (equivalent to
2050e1850 BCE in calendar years; see caption to Table 2 on how
dates are expressed in the present paper). The wetter climate since
12,500e10,000 BP caused a great expansion in the area of Uganda
climatically suitable for rainforest, many rainforest species
responding by expanding their ranges eastwards from a former ice-
age refuge centred in Kivu in the Democratic Republic of Congo (DR
Congo). Increased evaporation from an enlarged Lake Victoria
would have helped sustain precipitation in a zone to the north of
the lake, as is the case today. A consequence of this forest expansion
was the development of a gradient of decreasing number of forest
species from west to east, related to their differential abilities to
spread. Birds, primates, butterflies and trees all share this pattern
(Hamilton, 1975, 1976; Howard, 1991). Other factors being equal
(such as climate and altitude), the forests with the greatest number
of species in Uganda are those nearer to the former Kivu refugium,
such as Bwindi-Impenetrable and Semliki.
Until about 1000 BCE, the people living in the Great Lakes region
lacked agriculture or domestic stock and relied on hunting, fishing
and the gathering of wild foodstuffs for their subsistence. These
people were likely speakers of Khoisan languages, which are today
spoken mainly in Botswana and Namibia, with relict outliers in
Tanzania (Ehret, 1998). The knowledge of wild plants of these
people is likely to have been exceptionally great, judging by analogy
with modern-day hunter-gatherers, and it is possible that some of
their knowledge has passed down through cultural strands to the
present-day inhabitants of the region. The Batwa (‘pygmies’) living
near Bwindi-Impenetrable forest, the people most orientated to-
wards the forest environment in Uganda, have an exceptional
knowledge of nature (Byarugaba, 2008). The Batwa in Uganda
speak Bantu languages.
3.2. Agriculture and crops
Linguistic research has demonstrated that speakers of at least
two language families, Nilo-Saharan and Niger-Congo, contributed
to the development of early agriculture in Uganda (Ehret, 1998,
2011; Schoenbrun, 1993b, 1998). Speakers of yet another language
family (Afroasian) may have been present in the Great Lakes region
at the relevant time and may have had agriculture. The Nilo-
Saharan and Niger-Congo speakers (represented by its Bantu sub-
group) practiced different forms of agriculture. The former, living
in drier parts, grew the cereals sorghum (Sorghum bicolor (L.)
Moench), pearl millet (Pennisetum glaucum (L.) Br.) and finger
millet (Eleusine coracana Gaertn.), all earlier domesticated further
north in Africa, as well as sesame (Sesamum indicum L.), bambara
groundnut (Vigna subterranea (L.) Verdc.) and cowpea (Vigna
unguiculata (L.) Walp.). Their domestic animals included cattle,
goats and sheep (all earlier domesticated in the Middle East or
northeast Africa) and they knew how to work iron. In contrast, the
Bantu speakers used a planting (contrasted with sowing) form of
agriculture, more suited to growing crops in clearings made in
rainforest, just as their ancestors had been doing for generations.
The presence of loan words of Nilo-Saharan origin in the modern
Bantu languages of the Great Lakes region shows that the Bantu-
speaking people acquired knowledge of the growing of cereals,
the keeping of cattle and how to work iron from Nilo-Saharan
speakers. Linguistic research further indicates that the localities
of these cultural transfers lay to the southwest (later, within the
southwest) of Uganda and their timing to the first millennium BCE
(Ehret, 1998).
Today there are about 300 Bantu languages in Africa spread
throughout much of its east, centre and south. All are descended
from a common ancestral language (Proto-Bantu), spoken at
~3000 BCE close to the present-day border between Nigeria and
Cameroon (Derek and Philippson, 2003). Comparative linguistics
has allowed some reconstruction of the way of life of the Proto-
Bantu, suggesting that they practiced agriculture in small clear-
ings made in rainforest, interspersed with long periods of forest
fallow (Ehret, 1982, 1998). Yams (Dioscorea) constituted their staple
food and they also grew bambara groundnut, another legume
(probably cowpea), castor bean (Ricinus communis L.) and gourds
(Lagenaria siceraria (Molina) Standl.). The oil palm (Elaeis guineensis
L.) and the raffia palm (Raphia monbuttorum Drude) were planted
or wild-nurtured.
Crops grown today in Uganda have diverse origins. Several were
first domesticated in Africa, such as those mentioned above. Do-
mesticates originally from Asia include the banana, cocoyam (C.
esculenta (L.) Schott.), sugarcane (Saccharum officinarum L.), water
yam (Dioscorea alata L.) and Asian rice (Oryza sativa L.). America has
contributed sweet potato (Ipomoea batatas (L.) Lam.), kidney bean
(P. vulgaris L.), cassava (Manihot esculenta Crantz), peanut (Arachis
hypogaea L.) and maize (Zea mays L.). Linguistic studies provide
evidence for the dates of arrival in the Great Lakes region of some of
these crops (Ehret, 2011). Maize, kidney bean and peanut were
present by ~1800 CE, but Asian rice and cassava came later, the
former possibly with Swahili trading caravans (from ~1840) and the
latter possibly not until colonial times, when its adoption was
promoted as a famine crop. The introduction of new crops has
caused the extensive displacement of indigenous crops of compa-
rable dietary or ecological properties. Thus, the banana has sub-
stantially replaced Dioscorea yams, peanut the bambara groundnut,
and kidney bean the cowpea. Substitution is continuing today with
maize extensively replacing finger millet (which is labour-
demanding).
Fossils provide sporadic insights into the history of crops. Im-
pressions of pseudostems (‘trunks’) of the family Musaceae are
preserved in slag associated with iron furnaces of Later Iron date,
mostly dating to the 18th or 19th centuries (Fig. 2) (Iles, 2009). They
are thought likely to be from banana plants, but Ensete is a possi-
bility (see below). A phytolith of maize has been identified in
sediments dated 1780 CE at Munsa (Lejja et al., 2005). Pollen of the
castor bean has been found in sediments dating from 1300 CE
onwards in Lake Wandakara and the same sediments contain a rise
in abundance of pollen of the wild date palm (Phoenix reclinata
Jacq.) from 1750 CE (Ssemmanda et al., 2005). The castor bean is a
plant long cultivated (or at least wild tended) in Africa, while the
wild date palm, though not cultivated in Uganda today, is never-
theless a plant of great economic value, supplying many products.
Possibly Phoenix was encouraged through removing competing
plants. Pollen grains of sorghum and finger millet have been
identified from secure (i.e. non-contaminated) Early Iron Age
archaeological sites in Rwanda, dated respectively to the 3rde4th
and 5the6th centuries AD (Van Grunderbeek and Roche, 2007).
The conventional story of the banana in Africa is that it was one
of a suite of crops introduced from Southeast Asia to the coastal
fringes of East Africa during the first millennium CE, later carried
inland and thenwidely dispersed. People from Southeast Asia were
certainly capable of trans-oceanic travel at the time, given that the
language of Madagascar (Malagasy) has its closest modern relative
in Borneo and the earliest human occupancy of Madagascar dates
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4428
to the first few centuries CE. Types of bananas may have arrived in
waves, first the ancestral stock of Plantains, then that of the AAA-EA
bananas and finally the varied members of the Indian Ocean
Complex (De Langhe et al., 1994-5). The country inland of the East
African coast is too dry for moisture-loving crops like the banana,
but there are passages of easier penetration, such as up the Ruvuma
valley to Malawi and then up the highlands along the western Rift
Valley to Uganda (Wrigley, 1989). It has been suggested that the
banana may have become known to Bantu-speaking farmers in the
Great Lakes region by 500e900 CE (Schoenbrun, 1993a), possibly
becoming popular as a nutritional and ecological replacement for
Ensete (De Langhe et al., 1994e5). Ensete is a banana-like plant that,
unlike the banana, is indigenous to Africa and can be eaten. How-
ever, it is not the fruit of Ensete that is eaten, but rather the root-
stock, stem of the fruit bunch, the young tender leaves inside the
pseudostem and sometimes the seeds (ground into flour). Although
apparently not eaten in Uganda today, Ensete ventricosum (Welw.)
Cheesman (ekitembe), the locally occurring species, is reported as
being eaten historically (Thomas, 1940). Ekitembe is valued in
modern Uganda as a source of medicine and for its seeds (empiki,
used as counters in the game of omweso), and as a decorative
addition to courtyards. Elsewhere in eastern Africa, E. ventricosum
provides the staple food in parts of Ethiopia.
There is an alternative hypothesis about the history of the ba-
nana in Africa, proposing a much earlier presence. Evidence quoted
includes the existence of a large number of varieties of Plantain in
the forest zone of central Africa, a reconstructed root word (*kondo)
for Plantain in Proto-Bantu and phytoliths of bananas (Musa) found
in archaeological settings at Nkanga in Cameroon (dating to the 1st
millennium BCE) and Munsa in Uganda (dating to the 4th millen-
nium BCE) (Blench, 2009; De Langhe, 2007; Lejju et al., 2006;
Mbida et al., 2001). Objections have been raised on several
accounts. The existence of a large number of named varieties of a
crop does not necessarily indicate great antiquity, as shown by the
morphologically mutable Nfuuka clone set of AAA-EA bananas in
Uganda (Tugume et al., 2002). No detailed analyses of the historical
implications of banana terminology are included in authoritative
works on comparative Bantu linguistics (Ehret, 1982, 1998;
Schoenbrun, 1998). The identification of the phytoliths has been
questioned, as well as the dating in the case of Munsa (Newmann
and Hildebrand, 2009).
3.3. Human influences on forests before 1900
Charcoal is common in soils under rainforests in tropical Africa,
mostly interpretable as originating through small-scale slash and
burn agriculture (Vleminckx et al., 2014). One site investigated,
200 km to the west of Uganda, is the Ituri basin (DR Congo), where
studies of the anatomy of the charcoal have revealed remarkable
differences between the modern flora and that which the charcoal
represents (Hart et al., 1996). Only one species (Cynometra alexandri
C.H. Wright) is abundant in both cases, 14 of the 36 species iden-
tified in the charcoal are absent from the forest today and one of the
modern forest dominants (Gilbertiodendron dewevrei (De Wild.) J.
Leonard) is completely absent from the charcoal record. Radio-
carbon dating of 28 samples of the charcoal gave a spread of dates
between 2850 BCE and recent, though with only 3 dates older than
200 BCE. The period 200 BCE to the present is fairly evenly covered
by the radiocarbon dates, which, together with their pattern of
geographical distribution, suggests that burning was a continuing
phenomenon, though of limited extent on each occasion. This is
just as would be expected for the type of agriculture reconstructed
for the early Bantu. Analyses of forest charcoal from the western
side of the central African rainforest support the hypothesis of slash
Fig. 2. Archaeological and other sites in Uganda yielding evidence of pre-1900 AD influences of people on forests. Iron smelting areas after (Iles, 2009). The Luganda names of some
geographical features are given in italics.
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 29
Table 3
Sites of pollen diagrams from Uganda providing evidence (or possible evidence) of past influence of people on forest. Dates in calendar years, calibrated where necessary from
radiocarbon dates (Reimer et al., 2009). Further explanatory notes in Appendix 1.
Site and altitude (m) Type of site Immediate surrounding landscape Past human influences
1. High altitude sites
Muhavura, Virunga Volcanoes, 4127 ma Summit crater lake Afroalpine vegetation Widespread forest clearance around
mountains, very well dated at ~1000 CE.
Peaks in charcoal in the sediments
accompany the palynological indicators
of forest clearance. Floristic
composition of montane forest or
woodland altered at ~1000 CE. The
same results for the two sites inspires
confidence.
Gahinga, Virunga Volcanoes, 3474 ma Summit crater bog
Kitandara, Rwenzori 3990 mb Lakes Afroalpine vegetation Widespread forest clearance in
lowlands around mountains at ~1000
CE (the date is interpolated from
considerably older radiocarbon dates).
Forest clearance greater to the east than
the west.
Bujuku, Rwenzori 3920 mb
Mahoma, Rwenzori 2960 mb Bamboo forest
2. Sites in the Rukiga Highlands
Muchoya, 2260 mc,d Valley swamps and
a lake (Bunyonyi)
Bamboo forest Signs of forest disturbance from
~225 BCE, more so from ~1250 CE. Some
forest always remaining. Change in
swamp vegetation during first
millennium CE.
Mubwindi, 2100 me Broadleaved forest Slopes around swamp forested
throughout. Signs of human
disturbance from ~1650 CE.
Katenga, 1980 mf Small-scale farming, scrub, pasture Major forest clearance with soil erosion
and swamp siltation. Two episodes of
forest disturbance at Ahakakyezi, ~1700
e750 BCE and ~700 CE-present; soil
erosion with second episode; final
clearance of ridge forest at ~1150 CE.
Bunyonyi, 1950 mf
Ahakagyezi, 1830 md,g,h
3. Crater sediments, Kasenda (Ndale) Volcanic Field
Kabata, 1370 mi Crater swamp Small-scale farming, grassland; forest
nearby
Some opening up of forest at ~1600 CE;
possible human disturbance earlier
(sometime between 1350 BCE and
400 CE). Spread of papyrus over a lake
sometime between 400 and 1400 CE.
Kasenda, 1260 mj Crater lakes Forest around sites replaced by
grassland, well dated at ~900e1000 CE.
Some shrub and forest tree regrowth
from ~1700 to 1750 CE (especially from
late 1800s).
Wandakara, 1170 mj
4. Swamp associated with a Later Iron Age settlement at Munsa
Munsa, 1220 mk Papyrus swamp Small-scale farming, grass, forest
patches
Forest clearance well dated at ~1100 CE
with soil erosion and swamp siltation.
Economy established with cereal
cultivation, cattle-keeping, iron-
smelting. Some forest recovery from
~1780 CE.
5. Large lowland lake
Pilkington Bay, Lake Victoria, 1134 ml Huge lake Farmland, savannah, forest Major forest clearance, well dated at ~1
CE, shown by a major decrease in the
ratio of forest to grass pollen.
Accompanied by changes in wetland
vegetation. Absolute decline in forest
tree pollen starts earlier, sometime
between 1750 and 1250 BCE.
Sources:
a (McGlynn et al., 2013).
b (Livingstone, 1967).
c (Morrison, 1968).
d (Taylor, 1990).
e (Marchant et al., 1997).
f (Morrison and Hamilton, 1974).
g (Hamilton et al., 1986).
h (Hamilton et al., 1989).
i (Taylor et al., 1999).
j (Ssemmanda et al., 2005).
k (Lejja et al., 2005).
l (Kendall, 1969).
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4430
and burn agriculture for much of its origin, but here there are hi-
atuses in agriculture not found at Ituri, at 450e1200 CE in Gabon
and 550e1650 CE in Cameroon (Oslisly and White, 2007;
Vleminckx et al., 2014).
The evidence from Ituri suggests that people caused major
changes to the floristic composition of the rainforest. A similar
conclusion has been reached from studies of botanical remains at
archaeological sites in Gabon, the researchers further com-
menting that the people may have influenced the floristic
composition of the forest in three ways, the inadvertent
encouragement of species adapted to establishment in gaps
following agriculture, the nurturing of valued species and
possibly planting (Oslisly and White, 2007). Endocarps of oil
palm (Elaeis guineensis Jacq.) and Canarium schweinfurthii Engl.
are common at archaeological sites in Cameroon and Gabon
showing that they were prized by the early Bantu. Canarium
(omuwafu) is a large tree held in high esteem in the Central
Region of Uganda today, yielding edible fruits (empafu), resin
used as incense (obubaane) and valued for its statuesque form
and gentle shade-giving qualities. It is common in banana gar-
dens, but rarely seen in dense forest.
The identification and counting of fossil pollen contained within
sediments of Upper Quaternary age (last 40,000 years) have
allowed the reconstruction of the environmental history of parts of
Uganda. This involves the reconstruction of past vegetation from
the pollen spectra and then the reconstruction of past environ-
mental variables from the reconstructed vegetation, processes
aided by knowledge of the modern pollen rain and the ecology of
the parent taxa of the pollen types (Hamilton, 1972; Hamilton and
Perrott, 1980, 1981). Considerable uncertainties remain and there-
fore new interpretations may arise as new information comes to
light. Distinguishing between the influences of past climates and
people on the vegetation can be problematic, especially during
those earlier years when relatively low-impact agriculture was (or
might have been) practiced (Jolly et al., 1997; Kiage and Liu, 2006).
Linguistic evidence indicates that agriculture could have been in
Uganda before 1000 BCE.
Fig. 2 shows the localities for which pollen diagrams of Upper
Quaternary age are available. Sites yielding pollen diagrams
showing (or possibly showing) past human influence on forest
are listed on Table 3 with notes in Appendix 1 explaining how
this has been inferred. Sites are organised on Table 3 according to
their geographical distribution and interpretive qualities. Sites at
high altitudes and large lakes can be especially useful for
reconstructing landscape-level changes in climate and human
influence, since they sample the pollen rain originating from
extensive areas (Hamilton, 1972; Hamilton and Perrott, 1980).
Pollen diagrams from closely-spaced localities can be useful for
differentiating local factors influencing past vegetation from
those that were more widespread (Lejja et al., 2005; Ryves et al.,
2011).
The most striking evidence of past human influence on forests,
evident in several pollen diagrams, is an episode of major clear-
ance of forest at ~1000 CE (range 700e1250 CE). All the pollen
diagrams showing this event are from sites in mid- to southwest
Uganda, a geography that reflects the distribution of sites studied
and not necessarily the area to which forest clearance was
confined. The pollen spectra, combined with other characteristics
of the sediments, show that soil erosion sometimes accompanied
the forest clearance, influencing wetland vegetation through
siltation.
The date of ~1000 CE marks a significant transition in the
archaeological record of the Great Lakes region, from the Early to
Later Iron Age and with the pottery type changing from Urewe to
rouletted ware. The onset of the Later Iron Age is dated
archaeologically to the 9th century CE in north-east Rwanda and
to between the 11th and 14th centuries at Ntusi, Munsa and Bigo,
sites of large-scale earthworks constructed during the Later Iron
Age in western Uganda (Fig. 2) (Schoenbrun, 1998). New types of
political structures with greater social stratification are believed
to have emerged (Lejja et al., 2005). Oral tradition in Buganda
traces the present Kintu dynasty back to a founding monarch
(Kabaka Kato Kintu), who is estimated to have reigned at
1200e1230 CE (Nuwagaba, 2014). A contributing factor to social
and political change may have been the acquisition of more
productive forms of food production, based on the development
of intensive banana gardening around Lake Victoria and large-
scale cattle-based pastoralism in the region that later became
the kingdom of Bunyoro-Kitara to the west (Schoenbrun, 1993a,
1998). Oral tradition in Buganda further states that the people
who previously occupied the land that became Buganda were
known as the Balasangeye (meaning ‘they shoot at colobus
monkeys’) and that they were wanderers lacking fixed abode
(Nuwagaba, 2014). This seems a reasonable description of a
people practicing shifting agriculture and hunting animals in
rainforest.
In addition to the major forest clearance event at ~1000 CE,
some earlier and later human influences on forests can be
detected in the pollen diagrams. Taking a fresh look at the evi-
dence (Appendix 1), it is suggested that the most persuasive signs
of forest disturbance before ~1000 CE are in pollen diagrams from
Lake Victoria (forest clearance from ~1 CE), Muchoya (forest
disturbance from ~225 BCE) and Ahakagyezi (forest disturbance
phase ~1700e750 BCE). These early human influences on forests
were relatively subdued compared with the obvious ~1000 CE
event and seemingly do not warrant the degree of detailed
reconstruction of past human influences previously made
(Schoenbrun, 1994; Taylor et al., 1999). On the other hand, the
pollen evidence broadly substantiates the story of the influence
of early agriculturalists on forests reconstructed from linguistic
and charcoal analyses, that is, that their long-fallow type of forest
agriculture caused rather little disruption to the overall physical
structure of the forests.
The introduction of intensive banana gardening is unlikely to be
the reason for early forest disturbance at Muchoya and Ahakagyezi
or the obvious major episodes of forest clearance seen at these and
other sides in the Rukiga Highlands later (Table 3). This is because
temperatures would probably have been too low. Bananas are
grown around some of the lower altitude of these sites today, but
such altitudes were considered too cold for bananas in the 1950s
(Edel,1957). The upper altitudinal limit of banana growing has risen
in the Rukiga Highlands since 1970, similar to the upward move-
ment of crops recorded for the East Usambara Mountains, Tanzania
(Hamilton and Bensted Smith, 1989). Another biological change
since the 1970s common to the Rukiga Highlands and the East
Usambaras, is an upward movement of malaria. Possibly the Rukiga
Highlands were attractive to early farmers because they were
malaria-free.
Regarding events after ~1000 CE, the pollen diagrams show that
the more open landscape that had been created was generally
maintained, though with some forest regrowth at Kasenda and
Wandakara (from ~1700 to 1750 CE, especially after 1800 CE) and
Munsa (from ~1780 CE) (Lejja et al., 2005; Ryves et al., 2011;
Ssemmanda et al., 2005). Various factors may have been causa-
tive, including socio-economic change (Lejja et al., 2005). One
factor known to have contributed to the spread of forest historically
is disease. Large areas of southern Busoga and elsewhere were
depopulated by a sleeping sickness epidemic at the beginning of
the 20th century, leading to the substantial spread of colonising
forest (Hamilton, 1984).
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 31
4. Plant diversity and plant resource management since 1900
4.1. New concepts of land ownership and resource rights
The relationship between people and plants in Uganda has
changed greatly since 1900, consequent to major changes in soci-
ety, economy and culture. The country came into existence through
British colonialism, the first European visitors arriving in 1862, a
Uganda Protectorate declared in 1894 and the boundaries of the
modern state fixed by about 1914. A new concept of private
ownership of land was introduced, contrasting sharply with the
many types of customary tenure prevailing beforehand. Rights to
land in Buganda were traditionally vested in the king (Kabaka) or
heads of clans (Abakasolya), who then allocated it to their subjects
or clan members (Lunyiigo, 2011; West, 1965). Land was not
regarded as private property in the exclusive European sense.
Rather, political and economic power was considered to be
fundamentally related to people, not land, as summed up in the
Luganda proverb: ‘Omwami tafuga ttaka afuga bantu’. (‘A chief does
not rule land, he rules people.’).
The principal law governing land issues today is the Land Act
(1998), which recognises four forms of land tenure e customary,
leasehold, freehold and mailo (the latter applying only to Buganda
e see below). The government also holds land in trust on behalf of
the people of Uganda as a whole, including forest reserves and
national parks. About 75%e80% of land holdings are unregistered
customary properties, while most freehold land lies in the former
administrative districts of Ankole, Toro, Kigezi and Bugisu (USAID,
2015). Provisions in the Land Act allow customary and leasehold
land held by Ugandans to be converted into freehold, though, in
reality, little customary land has been so converted because the
procedures to obtain the required Certificates of Customary
Ownership are so cumbersome (FOE, 2012). Holders of customary
land can be vulnerable to losing their holdings.
A seminal event was the Uganda Agreement (1900) reached
between the colonial administration and the Kingdom of Buganda.
This parcelled up all the land of Buganda among several benefi-
ciaries, the principal winners being the British Protectorate Gov-
ernment and a number of ‘chiefs and private landowners’ (whose
land became known as mailo land) (Table 4). The losers were the
traditional clan chiefs (abataka), whose claims to their customary
land holdings were brushed aside, and the common people (aba-
kopi), who became (and may remain) liable to summary eviction at
the whim of legal landowners. However, the Uganda Agreement
did contain some provisions permitting customary access on Pro-
tectorate Land, stating that, once forestry regulations had become
defined, “the claims of the Baganda people to obtain timber for
building purposes, firewood, and other products of the forests or un-
cultivated lands, shall be taken into account, and arrangements made
by which under due safeguards against abuse these rights may be
exercised gratis”. The Uganda Agreement was a hastily drawn-up
document which has led to many subsequent complexities and
disputes (Lunyiigo, 2011; West, 1965). It is likely that the British
official responsible for its framing (Sir Harry Johnston) was moti-
vated mainly by a desire to gain access to ‘unoccupied’ land for
large-scale British settlement (which, in the event, never materi-
alised), a goal achieved through granting excessive land privileges
to the ruling classes.
Lunyiigo has commented on the use of the words ‘waste and
uncultivated land’ in the Uganda Agreement (Table 4) (Lunyiigo,
2011): “In a hunting and shifting cultivation economy it is not
possible to describe land as either wasteland or unoccupied. These so-
called waste and unoccupied lands were either hunting grounds or
areas preserved to move into when land is exhausted elsewhere”. The
idea that much of the land was ‘wild’, an adjective historically often
applied to Africa by Europeans (Adams and McShane, 1992), is not
born out by the ways that natural resources are regarded today
(with plants from many types of habitat being used and managed,
though with varying degrees of intensity) nor by the historical
evidence (which shows that the extent and floristic composition of
forests have long been influenced by people). Judging by analogy
with other parts of the world (Pei, 2010; Pei et al., 2009), people
would likely have practiced ‘indigenous conservation’, that is, sys-
tems of belief and related practices that would have tended to
maintain the vital natural resources upon which they depended.
Sacred groves, totemic animals and retention of particular speci-
mens of trees have been noted in Uganda (Nuwagaba, 2014;
Osmaston, 1968; Sembajjwe, 1995), but otherwise indigenous
conservation has been little documented.
The concept of mailo land was not extended to other parts of
Uganda, though two components of the Uganda Agreement were,
namely the possibility of registering land as private property and
Table 4
Allocation of land in Buganda under the Uganda Agreement of 1900 (West, 1965).
Beneficiary Total area Components
sq. mi. km2 sq. mi. km2
Protectorate Government 10,550 27,324 Forestsa 1500 3885
Waste and uncultivated landb 9000 23,310
Government stations 50 129
One thousand chiefs and private landownersc 8000 20,720
The Kabaka and other dignitaries 958 2481 Private property 750 1942
Land attached to their offices 208 539
Mission societies 92 238
Estimated total area of Buganda 19,600d 50,764
a The Uganda Memorandum of Agreement (Forest) of 25th October 1907 defined the extent to which forest could be included inmailo land (the part allocated to ‘chiefs and
private landowners’). In general, all patches of forest over 0.5 sq. mi. (1.3 km2) were to be assigned to the Protectorate Government.
b The total area of ‘waste and uncultivated land’ became reduced to an estimated 8307 sq. mi. (21,515 km2) once the actual area of Buganda became better known and was
reduced again to 6804 sq. mi. (17,622 km2) when the counties of Buyaga and Bugangazi (Bugangaizi) were transferred from Buganda to Bunyoro following a referendum in
1964. This land is sometimes known as mailo akenda (‘the nine thousand mailo land’) (Mutengesa, 2012).
c The land distributed to ‘chiefs and landowners’ came to be known as mailo land (from English ‘mile’). It appears that the original intention of the British was that there
would be about 1000e1030 recipients. However, distribution ofmailo land was made the responsibility of the Buganda parliament (lukiiko) under the Uganda Agreement and
land came to be distributed to many more people than the British had apparently intended. The first Allotment List had 3650 names, then, with yet more added, the total
number of allotees rose to 4138 in the first authoritative list (1905). Many of these claims had little or nothing to justify them. Numerous transactions in mailo land then
followed (many not officially documented), resulting in an estimated total of 100,000 holders of mailo land by 1963.
d The total area of Buganda at the completion of the originalmailo survey in 1936 was found to be 17,310 sq. mi. (44,833 km2). This resulted in a reduction in the area of land
assigned to the Protectorate Government (in its position as recipient of the residue of the estate).
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4432
the bringing of larger areas of forest under government control. The
actual registration of forests in Buganda as the property of the
Protectorate Government was slow, partly because unexpectedly
large numbers of small forest patches were found to have come into
private ownership. It had originally been estimated that the total
area of forest on land assigned to ‘chiefs and private landowners’
was 260 km2, but a survey carried out in 1956e1960 revealed the
true figure to be about 1550 km2 (Webster and Osmaston, 2003).
Out of a total of 3885 km2 of forest intended to come under gov-
ernment control in 1900 (Table 4), only 1373 km2 had actually been
registered by 1965.
The gaining of political independence by Uganda (1962) was
accompanied, shortly before and after, by major changes
relating to the disposition of land. A new agreement (the ‘new
Buganda Agreement’) was forged between the British Govern-
ment and the Kingdom of Buganda in 1961, transferring almost
all land in Buganda then classified as Crown (or Public) Land
out of the control of the Protectorate Government to the
Kingdom of Buganda (Colonial Office, 1961). Some exceptions
were made for the wider national interest, for example relating
to control over land in towns. In essence, the land that became
transferred was that which had been classified as ‘waste and
uncultivated’ in the Uganda Agreement, plus all government-
owned forests (except for those that lay within the Munici-
pality of Kampala). Later, a political coup (1966) led to the
abolition of the federal system of government prevailing be-
forehand (during both colonial and independence times) and
the centralisation of all political power. Advisory services in
agricultural and forestry were transferred to the central gov-
ernment and Local Forest Reserves (LFRs, see next section)
became absorbed into the central forest estate.
Land issues remain contentious and there are numerous un-
certainties and disputes (Lunyiigo, 2011; Rugadya, 1999; USAID,
2015). The expulsion of ‘Asians’ from Uganda in 1972 was
accompanied by the declaration of an Economic War, an
announcement interpreted by some that they were now free to
settle anywhere they liked, including in forest reserves
(Hamilton, 1984). The Land Act of 1998 granted responsibility for
managing land resources to the districts, a step that resulted in
many government forests becoming converted to agriculture or
destructively harvested for charcoal (Kabogozza, 2011). The same
act makes it possible to convert leasehold land to freehold. It was
concern about this that reportedly led to the use of the word
‘license’ rather than ‘lease’ in agreements reached between
forestry authorities and private sector operators following a
change in policy in 2001 encouraging the outsourcing of forestry
activities. However, legalistic caution seems to have arrived too
late or to have been too ineffective to prevent the effective
transfer of a substantial area of former forest reserves into pri-
vate hands, as suggested by the virtual disappearance of Local
Forest Reserves (LFRs) and a great expansion in the area of non-
mailo private forest (see next section). ‘Elites’ (as they can be
called) can be disproportionately advantaged over ordinary
people in bargaining over land issues, having better access to
finance, information, legal advice and decision-makers
(Twongyirwe et al., 2015).
A growing trend has been the lease of land by the government to
foreign investors, estimated to amount to 4%e8% of the country by
2011 (FOE, 2012). This is part of a global movement in which land,
agriculture and forestry have come to be regarded as secure sectors
for long-term investment. Land that is (or was until recently)
covered by natural forest has been acquired by investors, as on
Bugala Island and Mt Elgon, and in Bukaleba Central Forest Reserve
(CFR). Disputes with local people are common (FOE, 2012; Lyons
et al., 2014).
4.2. Forests and forestry
Colonial forestry was initiated in 1898 with the creation of a
Scientific and Forestry Department, followed by establishment of a
Forest Department (1917) and adoption of a formal forestry policy
(1929) (Hamilton, 1984). This policy stressed the need to press
aheadwith the reservation of forests, so that they could be properly
managed for the production of timber and the protection of
ecosystem services, with climatic moderation and provision of
water supplies specifically mentioned (Nicholson, 1929). Mountain
forests were recognised as especially important for environmental
protection and efforts were made to maintain all forests on
mountains above an altitude of ca. 2150 m. A two-tier system of
forest administration was developed, with larger blocks of forest
declared Central Forest Reserves (CFRs), coming under the direct
authority of the central government, and smaller forests made
Local Forest Reserves (LFRs), falling under local governments and
aimed at meeting local needs.
After Uganda gained political independence (1962), the local
government of Buganda was active in enlarging its forestry estate,
declaring 1373 km2 of new forest reserves during the period
1964e1966 alone (Hamilton, 1984). The total area of forest reserves
(of all types) probably reached its maximum extent in 1966, at
which time all larger blocks of rainforest were included in reserves,
as well as sizable areas of wooded savannah. Many small planta-
tions, mostly of introduced species, had been established.
Several species of trees have been introduced into Uganda for
forestry purposes, notably eucalyptus (especially Eucalyptus gran-
dis W. Hill ex Maiden, introduced 1912), cypress (Cupressus lusi-
tanica Mill., used in the first conifer plantations in the country,
established late 1940s) and pines (especially Pinus caribaea
Morolet). The planting of exotic species has become increasingly
emphasised in forestry over the years, for instance through an
adjustment to forest policy in 1971e1973 (Lockwood Consultants
Ltd., 1973), in a new forest policy in 2001 and a concentration
on exotics in most carbon capture projects. It is hoped that these
plantings will help meet projected shortfalls in the supply of wood
and take pressure off indigenous forests, taking advantage of
potentially rapid growth rates (Jacovelli et al., 2009). However,
whether pressure is actually reduced on indigenous forest will
depend on several factors, such as whether the types of people
who currently support their livelihoods by harvesting products
from indigenous forest to sell will also benefit financially from the
planting of exotics.
Perhaps diverted by this concentration on exotics, less effective
attention has been given to the management of natural forests and
the planting of indigenous trees. Roadside nurseries often offer
large numbers of seedlings of pines and eucalyptus for sale, but it
can be hard to find seedlings of indigenous trees (Galabuzi et al.,
2014). Ecosystem services have also become institutionally
neglected, as epitomised in this quotation from the forest policy
adjustment of 1971e1973: “there are secondary objectives such as the
protection of water catchments, soils, wildlife and amenity of land.
These however cannot be measured and are dependent on responsible
behaviour by (Forest) Department officials in their provision”
(Lockwood Consultants Ltd., 1973). The rate of deforestation, at
2.72% per year, has now become one of the highest in the world
(FAO, 2010a, 2010b). According to the first chairperson of the board
of the National Forest Authority (NFA) (see below) (Kabogozza,
2011): “there is no sustainable management of planted or natural
forests in Uganda. … The government has not supported the forest
sector with enough resources. … Also, given the fact that 64% of the
current forests are on private land, and nothing is done in terms of
forestry extension, it is not surprising that the highest degradation rate
is found in these areas”.
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 33
There have been two studies of forest loss and degradation at
the national level. The first, based on analysis of satellite imagery
and examination of Forest Department records covers the period to
1982 (Hamilton,1984). It found that the annual reports of the Forest
Department recorded only minor infringements of forestry regu-
lations in the years preceding 1970, but that there was evidence of
alarming levels of forest loss and degradation thereafter. The sec-
ond, a National Biomass Survey, based on analysis of satellite im-
agery backed up by sample plots, found that 9% of CFRs and 43% of
LFRs had become completely deforested by 2002 (Drichi, 2002).
(No differentiation is made in these percentages between forest
reserves covered by rainforest and those covered by other woody
vegetation types.) Appendix 2 provides examples of forest loss and
degradation since 1970.
The areas of rainforest under different forms of ownership in
2011 were reported as: National Forest Authority (NFA, 2836 km2),
Uganda Wildlife Authority (UWA, 2510 km2), private (2344 km2),
joint NFA/UWA (2346 km2) and LFRs (2.43 km2) (Kabogozza, 2011).
The figure for LFRs is startlingly low, considering that the total area
of LFRs was reported to be 3028 km2 in 1965, of which 1036 km2
was rainforest (Webster and Osmaston, 2003). Confirmation that
there has been a drastic reduction in the total area of LFRs is pro-
vided by another figure (50 km2), published in 2010 (LTS, 2010). The
high figure for private forests also merits comment. According to
interviews with senior foresters (see Acknowledgements), very
little of this is on the mailo land that was allocated to ‘chiefs and
private landowners’ under the provisions of the Uganda Agreement
in 1900, because most of the considerable area of rainforest that
once stood on such land has by nowbeen destroyed. Rather, most of
this forest is either on land in Buganda that was assigned to the
Protectorate Government under the Uganda Agreement and/or are
former Forest Reserves that have become private property (or, at
any rate, have become so regarded).
Forestry has been institutionally unstable over recent decades
(Table 5). There were two episodes of complete decentralisation of
the forest estate during the 1990s, followed by total or partial
recentralisation. It has been implied that this was related to
competing arguments about the best administrative structure to
manage natural resources (Banana et al., 2007), but actually, ac-
cording to interviews, the decentralisations (to district level) were
nearer to accidental by-products of major political events (general
decentralisation of government 1993; new constitution 1997) with
forestry given no particular consideration. In any case, the
decentralisations were not made with reference to the ethnic ge-
ography of the country (Nsita, 2005). The number of districts, the
pivotal unit of local government, has been multiplying, from 56 in
2002 to 111 in 2015.
The Forest Department itself was abolished in 2003 and
replaced by three new bodies, National Forest Authority (NFA),
District Forest Services (DFS) and Forest Sector Support Depart-
ment (FSSD). The ideawas that NFAwouldmanage CFRs, DFSwould
manage LFRs plus provide advice to private forest owners, and FSSD
would be a coordinator and regulator, without line responsibilities.
NFA was created as a semi-autonomous entity, making it free to
keep its own revenues, so potentially less dependent on the va-
garies of government funding. Government support for forestry
had declined greatly during the previous decade, one study in
Mpigi District finding that funding had been cut by 89% and staffing
by 68% over 1993e1995 (Banana et al., 2007).
A subsequent review of the forestry sector found that support
for DFS and FSSD never materialised and that these institutions
have been ineffective (LTS, 2010). In contrast, NFA was initially put
into operation effectively, though soon constrained by a presiden-
tial ban (2005) prohibiting the eviction of encroachers from CFRs.
The number of such encroachers stood at 180,000 in 2005 (officially
registered), mushrooming to an estimated 270,000 by 2010. The
original Board of NFA resigned or was replaced in 2006, reportedly
due to its opposition to government plans to hand over certain
areas of forest reserves for oil palm or sugarcane planting (BirdLife
International, 2008; Nakkazi, 2011; Tenywa, 2005, 2013; van Schaik
and Tickell, 2015; Veit, 2010) (Appendix 2). The review found that
NFA had declined greatly in effectiveness by 2010.
One reason for the failure to launch DFS and FSSD properly is
reported to be the withdrawal or reduction in levels of support
given by the Norwegian Aid for Development Cooperation
(NORAD) and the UKs Department for International Development
(DFID) to the Uganda Forest Sector Umbrella Programme (UFSUP,
1999e2003), charged with the restructuring of forestry. In DFIDs
case, internal changes may have contributed, since, at the time,
DFID was moving towards a single-minded focus on ‘poverty
reduction’ and a shift from ‘projects to programmes’ (Killick, 2005).
DFIDs support for UFSUP was reportedly classified as a project. The
standard of forestry advice available to DFID may anyway have
declined, given that the prestigious Oxford Forestry Institute was
closed in the 1980s, with DFIDs own tropical forestry team later
disbanded (Mills, 2006). NORAD has been the most consistent
Table 5
Institutional history of forestry in Uganda.
1898 First director of a new Scientific and Forestry Department appointed.
1917 Forest Department created.
1929 First formulation of forest policy, concentrating on forest reservation for environmental protection and timber production.
1929e1951 Large forests made Central Forest Reserves (CFRs) under the central government and small forests made Local Forest Reserves (LFRs) under
local governments. (However, a survey in 1956e1960 found that a considerable area of forest in Buganda had come to fall under private
hands.)
1967 CFRs and LFRs merged into the unitary category of Forest Reserves under the central government.
1971e1973 Forest policy adjusted favouring enlargement of conifer plantations for volume wood production. Little emphasis given to natural forest,
either for its protective functions or for productive purposes.
1993 All forest reserves decentralised to local government, except five of the larger forests (Bwindi-Impenetrable, Elgon, Kibale, Mgahinga,
Rwenzori) which were made national parks and transferred to the Uganda Wildlife Authority.
1995 All forest reserves recentralised.
1997 All forest reserves decentralised.
1998 Forest reserves over 100 ha recentralised (and labelled CFRs); forest reserves under 100 ha remaining with local authorities (and labelled
LFRs).
2001 New forest policy agreed, emphasising a greater role for the private sector in forestry operations.
2003 Forest Department replaced by: (1) National Forest Authority (NFA), responsible for CFRs; (2) District Forest Services (DFS), responsible for
LFRs and advice to private forest owners; (3) Forest Sector Support Department (FSSD), responsible for coordination and regulation.
2006 Board members of NFA resign or summarily dismissed, relating to conflict with the government over allocating parts of Mabira CFR and
forests on the Ssese Islands to investors. New board members appointed.
Sources: (Hamilton, 1984; Kabogozza, 2011; Sassen et al., 2013; Webster and Osmaston, 2003).
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4434
‘donor’ to forestry in Uganda, including through supporting the
founding of a Forestry Department at Makerere University (late
1960s), a National Tree Seed Centre (NTSC, in 1993) and a National
Biomass Study (1989e2002). The original intention was that NTSC
would make systematic collections of the germplasm of indigenous
trees (leaving the actual supply of seedlings to the private sector),
but today it concentrates mostly on exotic species.
Concerns about climate change have led to a market in carbon
credits developing in Uganda, mainly REDD (or REDDþ) schemes
(REDD ¼ Reducing Emissions from Deforestation and Forest
Degradation), with 97% of carbon credits sold to voluntary pur-
chasers in the European Union (Bulafu et al., 2013). REDD has been
severely criticised in general (Brown, 2013) and in relation to
Uganda in particular, where controversies over land ownership and
tenure and levels of corruption are regarded as unacceptably high
(Twongyirwe et al., 2015). A similar conclusion has been reached
for Kenya (Entenmann et al., 2014). Third party certification, as
would be necessary to establish credibility for REDD schemes, is
difficult to establish successfully in Uganda, as research into Fair-
trade tea and coffee has shown (Cramer et al., 2014).
REDD projects are considered too expensive to mount for
owners of smaller forest patches in Uganda (Bulafu et al., 2013), but
larger-scale projects have been launched by companies registered
in the Netherlands, Norway and the UK. The project of the FACE
Foundation (Forests Absorbing Carbon dioxide Emission) on Mt
Elgon differs from the others in its concentration on planting
indigenous rather than exotic trees. Launched in 1994 and based on
an agreement between the Dutch Electricity Board and UWA, the
objective is to plant indigenous trees on 250 km2 of land that earlier
had been illegally deforested (Appendix 2) (White and Wanyama,
2006). Provisions include a ban on the logging of the trees for a
period of 99 years and for all carbon credits to accrue to The
Netherlands.
Several organisms introduced by people into Uganda pose
problems for forest management. They include the rampant shrub
Lantana camara L., which can suppress the regeneration of indige-
nous species, and the fast-growing paper mulberry tree (Brousso-
netia papyrifera (L.) L. Vent.), which has spread rapidly in Budongo
and Mabira Forests, becoming dominant in parts of the latter
(Kisekka, 2012). The introduction of the Nile Perch (Lates niloticus
Linnaeus, 1758) into Lake Victoria in the 1950s has resulted in
added pressure on lakeside forests via several intermediate steps.
This fish has driven to extinction or near extinction hundreds of
species of small indigenous cichlid fish (enkejje) that used to form
the basis of a sizable artisanal fishing industry, the fishes being sun-
dried and then carried inland on bicycles to supply villagers with an
affordable source of protein. Nile Perch is too oily to dry properly in
the sun, so wood fuel is being used instead, hence the added
pressure on the forests. Cypress has suffered fromdamaging attacks
of cancer since the 1960s and eucalyptus and pines would seem
vulnerable to similar epidemics of pests or diseases, given that they
have been planted in extensive monospecific stands.
4.3. Planting and conservation of individual forest species
Small-holding farmers commonly plant a few species of indig-
enous forest trees, while many householders grow a few species of
medicinal plants (mostly herbs or shrubs) and herbal doctors can
have extensive collections. Several non-governmental organisa-
tions (NGOs) have promoted the planting of indigenous species by
communities, sometimes developing nurseries to supply seedlings,
including Rukararwe Development Centre (Bushenyi), Joint
Ethnobotanical Research and Advocacy (JERA), Uganda Group of
the African Network of Ethnobotanists and Ethnoecologists (UGA-
NEB) and Promotion de la Medicine Traditionelle (PROMETRA-
Uganda). Tooro Botanical Garden has developed the concept of a
‘first aid herbal toolkit’, a collection of about 20 species of medicinal
plants (some indigenous) intended for planting in home gardens
(Hamilton, 2008) and is also involved in forest restoration (BGCI,
2013). Especially valuable for supporting general biodiversity con-
servation is the growing of plants in the buffer zones of protected
areas to provide alternatives to species being overharvested within
them, as at Bwindi Impenetrable National Park (Cunningham,1996;
Wild and Mutebi, 1997). A manual on how to raise and plant 80
species of indigenous trees has been produced (Meunier et al.,
2010). The Forest Department started to develop techniques for
the enrichment planting of natural forests in the 1930s, involving
mahoganies (Khaya anthotheca C. DC. and Entandrophragma spp.) in
Budongo Forest and the general purpose timber species musizi
(Maesopsis eminii Engl.) in logged-over forests near Kampala, but
such attention to detail has become largely superseded by events.
At one time the Forest Department established nature reserves
within its larger forests, but these have little practical recognition
today (Howard, 1991). Only forests lying within national parks and
one forest reserve (Mpanga) receive much management attention
aimed specifically at biological conservation. A substantial field
survey of 12 principal forests in 1985e1988, involving inventories
of tree species, primates, birds and butterflies, resulted in calcula-
tion of a biodiversity importance value for each forest (Howard,
1991; Howard et al., 2000). This was then weighed up against the
interests of commercial forestry and the harvesting of minor forest
products, to provide optimal management objectives for each for-
est, treating the whole forest estate as a single planning unit. The
Forest Department was thwarted from further development of this
approach when it lost 5 of its larger forests to UWA in 1993.
The conservation status of trees in Uganda (829 species, of
which 455 live in ‘moist forest’) has been evaluated, finding that
only 1% are endangered (Kalema and Beentje, 2012). This evalua-
tion refers to the conservation status of species over their entire
ranges (few of the species are totally confined to Uganda) and the
authors concede: “There are, in fact, many species under threat in
Uganda through habitat loss or habitat erosion, through over-har-
vesting, and through other reasons”. Over-reliance on conservation
in neighbouring countries could be risky in the case of Uganda,
given that several of its neighbours have suffered from severe po-
litical challenges (DR Congo, Rwanda, South Sudan). A follow-up
national-level Red List assessment would be useful, as well as ini-
tiatives to conserve species identified as endangered. There is a
Uganda National Gene Bank in Entebbe Botanical Gardens, housing
mainly varieties of crops.
4.4. Banana diversity and its conservation
The British Empire, as with other European empires, was
strongly founded on trade in plants, so, following the common
practice, a botanical garden (Entebbe Botanic Gardens) was estab-
lished (1898) to serve as a testing station to identify species and
varieties of economic worth (Biggs, 1940; Tothill, 1940). Cotton and
coffee were soon recognised as prime candidates for general pro-
motion, their planting then being encouraged by imposing a hut tax
to encourage farmers to enter the monetary economy. Trials on
crops were shifted to agricultural stations in 1910 (Table 6), by
which datemany varieties of bananas had been imported, including
from Ceylon (Sri Lanka), Dominica, India, Jamaica and the UK (Kew
Botanical Gardens) (Thomas, 1940). Varieties of bananas have
continued to be introduced since 1910, in recent times principally
to Kawanda Agricultural Research Institute (KARI) and to its field
collection of bananas at Mbarara.
A decline in the productivity of bananas in the central area of
Bugandawas noted in the 1950s, thought to be related to exhausted
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 35
soils (Wrigley, 1989), and then again from the 1970s, with banana
diversity also diminishing, the causes reported as ravages by pests
and diseases, decreased soil fertility and socio-economic trends
(Karamura and Mgenzi, 2004; Mulumba et al., 2004). Some serious
pests and diseases that were seemingly absent before 1900 are
thought to have been introduced inadvertently along with banana
materials imported for planting (Blomme et al., 2012). They include
the banana weevil (Cosmopolites sordidus (Germar), which was
present by 1908), some damaging nematodes (notably Radopholus
similis (Cobb, 1893) Thorne, 1949), the pathogens responsible for
Sigatoka leaf spot (first seen 1938), Black Sigatoka (first recorded
1988), banana Xanthomonas wilt (BXW, first reported 2001) and
Fusariumwilt (first reported 1953) (Blomme et al., 2012). All banana
varieties in Uganda succumb to BXW, while AAA-EA bananas are
especially susceptible to weevils, R. similis and Black Sigatoka,
particularly at altitudes below 1400 m. The heart of commercial
banana growing has shifted from the Central to slightly higher parts
of the Western Region since 1980, partly because of reduced
problems with pests and diseases.
The maintenance of banana productivity and diversity in
Uganda has become a major concern for agricultural scientists,
given the importance of the crop in the diet (especially AAA-EA
varieties) and because the country is a major global centre of ge-
netic diversity for the crop. In situ conservation approaches have
mainly been limited to studying how farmers maintain banana
diversity in their gardens. Ex situ techniques suitable for conser-
vation of banana germplasm include field gene banks, in vitro cul-
ture and cryopreservation, the first being the most useful for plant
breeders (Pillay et al., 2004). Various field gene banks have been
started over the years, the principal current ones being at Sendusu,
associated with Namulonge Agricultural Research Institute, and at
Mbarara Zonal Agricultural and Development Institute (MZARDI).
The former belongs to the International Institute of Tropical Agri-
culture (IITA), while the latter falls under the National Agricultural
Research Organisation (NARO) (Table 6). Several field collections of
bananas in Uganda have been lost over time, the causes including
inadequate funding and civil strife. MZARDI is currently subject to a
land claim by an ex-army officer (Mukombozi, 2013).
Conventional banana breeding is one method that has been
tried in Uganda to make AAA-EA bananas less susceptible to pests
and diseases. AAA-EA bananas are triploid (3) and therefore
sterile, so do not normally produce viable seed. However, it has
been found that hand pollination with pollen from wild bananas,
especially the strain Musa acuminata spp. burmannicoides ‘Calcutta
4’, sometimes results in some bananas in a bunch having viable
seeds and, further, that some of the banana plants grown from
these seeds are resistant to pests and disease (Pillay et al., 2004).M.
acuminata is diploid (2) and the seeds produced from this
crossing are tetraploid (4) and so potentially fertile and may have
viable seeds (few to many). Consumers dislike bananas containing
seeds, so plant breeders have then back-crossed the tetraploids
with improved diploid varieties (2) to produce secondary trip-
loids (3) that are seedless.
The discovery in 1988 of Black Sigatoka, a particularly devas-
tating disease, caused the banana to rapidly become the priority
crop for urgent attention by plant breeders in Uganda. It triggered
the re-establishment of a banana collection at KARI (1989), the
development of a collaborative programme between NARO and IITA
and the launch of a formal banana breeding programme (1994)
(Kikulwe et al., 2007). Useful levels of resistance to pests and dis-
eases have not been found in Uganda, so germplasm of cultivars for
the breeding programme have been imported from elsewhere (in
the form of in vitro plantlets) (Kikulwe et al., 2007; Smale and
Tushemereirwe, 2007). Tissue culture techniques have been
developed for the multiplication of planting materials for delivery
to farmers, with commercial laboratories involved. Height, suck-
ering ability, time to flower, time to fill, bunch traits, yield, and
organoleptic quality have received attention in the breeding
programme.
A genetic engineering laboratory was established at KARI in
2003. Support for capacity-building has been received from
Biodiversity International, a conservation group that incorporates
Table 6
Field collections of bananas in Uganda. Sources: (Biggs, 1940; Blomme et al., 2012; Karamura and Mgenzi, 2004; Kikulwe et al., 2007; Thomas, 1940; Tothill, 1940).
Institute History
Entebbe Botanic Gardensa Founded 1898, especially to test the local suitability of potential economic crops.
Banana varieties were introduced from many countries. Work on bananas was
transferred to agricultural stations from 1910.
Kampala Plantation Banana varieties accumulated from Buganda and Ankole (1919e1925) and trials
of cooking bananas started (1927). The collection no long exists, related to
expansion of Kampala city.
Bukalasa Agricultural College (formerly Bukalasa Substation)b Trials on banana varieties started 1927 using materials obtained from Kampala
Plantation. The work was largely transferred to Kawanda in about 1940. A
banana collection was re-established in the 1960s, eventually containing 600
accessions, but lost by 1985.
Kawanda Agricultural Research Institute (KARI)a Banana collection started 1940, but later lost. It was restarted in 1989, triggered
by concern over discovery of Black Sikokota in Uganda (1988). When Uganda
started a banana breeding (2003), the Kawanda collection was transferred to
MZARDI. Kawanda then became developed as a collection of breeding lines.
Makerere University Agricultural Research Institute e Kabanyolo Banana collection established 1989, but lost by 2004. A few representative
samples exist in tissue culture.
Namulonge Agricultural Research Institutea Collection established in 2006e8 as part of a plan to move all research on crops
from Kawanda to Namulonge. It contains about 100 accessions. A banana
collection belonging to the International Institute of Tropical Agriculture (IITA)
was started at Sendusu, near Namulonge, in the 1990s.
Mbarara Zonal Agricultural Research and Development Institute (MZARDI)a Banana collection started 1998 as a reference collection and to duplicate the
collection at Kawanda. The collection became a regional collection in 2008 (for
DR Congo, Kenya, Tanzania, Uganda) within the framework of the Banana
Research Network for Eastern and Southern Africa (BARNESA). It currently has
450 accessions. It is run by the National Banana Programme (based in KARI) of
NARO, backstopped by Bioversity International. The altitude is 1410 m.
a Today under National Agricultural Research Organisation (NARO).
b Today under Ministry of Agriculture, Animal Industry and Fisheries.
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4436
the former International Network for the Improvement of Banana
and Plantain (INIBAP). A second potential avenue has thus been
opened up to develop strains based on AAA-EA bananas that have
resistance to pests and diseases or have other useful traits. Intro-
duced genes have come from varieties of bananas and a range of
other organisms (plants, animals and bacteria). Legislation does not
currently allow the release of genetically modified (GM) crops to
farmers.
5. Discussion: the future and some conservation suggestions
The present is distinctive in its rapid rates of change and high
interconnectivity. Uganda as a political entity was created recently
by historical standards, bringing together people with diverse
cultures. Some incidents of loss of forests or collections of banana
germplasm have occurred at times of disrupted government related
to tensions between the (centralised) state and traditional political
allegiances. Increased connectivity has led to the entry of invasive
species and new pests and diseases, heightening threats to indig-
enous plant diversity. It is not surprising that, under these cir-
cumstances, it has been hard to find effective ways to achieve
conservation of plants. Two predicted trends will make this task
even harder in the future e population growth (magnifying pres-
sures on natural resources) and climate change (causing shifts in
zones of natural vegetation and agriculture). The populationwas ca.
1.8 million in 1906 (HMSO, 1906) and will be over 100 million by
2050 if present trends continue (World Bank, 2015). Average annual
temperatures could rise by 1.5 C by 2030 (USAID, 2013).
Conservation of plant diversity will be advanced by people
aware of the issues and prepared tomake efforts for improvements.
The suggestions for conservation that follow deal with general
matters of orientation and coordination, rather thanwith particular
areas of specialisation in conservation, since those already involved
will be aware of the immediate challenges they face. We assume
that the present unfavourable enabling environment will continue,
while hoping for policy change.
We suggest an opportunistic approach to engagement at field
level, taking advantage of favourable local circumstances as they
arise. Given the present high levels of forest loss and degradation,
the retention or restoration of any area of rainforest can be
considered of value for the conservation of forest species. Efforts at
conservation across the landscape will anyway be needed to facil-
itate the survival of species under predicted climate change.
The local is the key level towards which conservation efforts
should be orientated, that is, where people are in direct physical
contact with plants. Progress at any other level (for instance,
identifying priority areas for conservation action or selling carbon
credits abroad) must feed into improved management on the
ground to be counted a success. Ex situ conservation should be
closely supportive of in situ conservation in the Ugandan context to
attract necessary support.
Species of plants have typically taken a very long time to evolve,
therefore the assessment that 20% of them are in danger of immi-
nent global extinction represents a calamitous loss of natural cap-
ital. However, people who are alive today, even if intellectually
aware of the problem, can have overriding concerns about their
own immediate livelihoods and the future of their children. Con-
servationists interested in the survival of plant diversity need social
allies. Those concerned with plant genetic resources in Uganda
engage with much the same systems of plant resource use and
management at field level as do those concerned with wild plant
species. We suggest closer coordination. In any case, wild plants do
not form a well-bounded category. There are many species of ‘wild’
plants that are semi-domesticated, the planting of ‘wild’ plants by
households is common, there is probably no forest in Uganda free
of human influence, and planting trees for forest restoration or
enrichment are recognised management practices.
Plant conservation is distinctive, in comparison to conservation
applied to other taxonomic categories, in that plants almost
everywhere provide products that contribute to human economies
and because of the major roles that they play in delivering many
ecosystem services. With few exceptions, it is unrealistic in Uganda
to devise systems of management to conserve species of wild
plants, unless attention is given to extractive use (of the same or
other species). Awareness of the roles that plants play in delivering
ecosystem services may reveal new possibilities for partnerships.
For instance, conservationists concerned about forest species may
be able to build alliances with elements of society concerned about
the availability of future water supplies, given the common
perception that a cover of indigenous forest helps to maintain flows
in streams. Those concerned with the survival of banana diversity
may be able to find allies among people anxious about cultural
survival, given the cultural significance of the banana garden in
parts of Uganda.
Assessing the conservation approaches and methodologies that
work best is a challenge, given the many potentially influencing
variables. We suggest an evidence-based approach to establishing
best practice, similar to that which has been so successful in
advancing medicine (Hamilton, 2011; Sackett et al., 1996;
Sutherland et al., 2004). This involves assessing where and why
more desirable (system) states exist and then using this knowledge
to promote improvements elsewhere. For example, it would be
interesting to knowwhy some farmers maintain a greater diversity
of indigenous varieties of bananas than others, and the processes
followed in Mpigi District that have led to the survival of some
patches of forest, while others have been lost (Appendix 2).
One reason why we have laid stress on institutional history in
relation to forestry and collections of banana germplasm is because
of the potential of institutions for directional effort over time,
gaining greater proficiency through experience and institutional
memory. A programme designed to answer the question ‘How can
communities best conserve their medicinal plants?’, involving three
case studies in Uganda (among others), has identified the central
roles that NGOs can play in conservation initiatives (Hamilton,
2008; Pei et al., 2010). Local, national and international NGOs can
take complementary roles. National NGOs are pivotal, on the one
hand connecting with community groups seeking local develop-
ment supportive of conservation goals, and, on the other hand, with
international NGOs able to facilitate exchanges of experiences be-
tween countries and sometimes having easier access to funds.
Building capacity for the approach to plant conservation sug-
gested here is a challenge. Ethnobotany is a key discipline because
it covers both the social and botanical aspects of plant conservation
and draws on both indigenous and scientific knowledge
(Cunningham, 2001; Martin, 1995; Tuxill and Nabhan, 2001).
Ethnobotany has been taught at Makerere University since 1998.
6. Conclusions
Inmany countries, plants hold a central position in the economy,
but suffer from low levels of support for plant conservation, ever
rising demands on natural resources, a tendency to place short-
term economic development above environmental concerns, and
vulnerability to climate change. It is suggested that they too could
benefit from an ecosystem-based approach to plant conservation,
covering sustainable use and delivery of ecosystem services, addi-
tional to conservation of species and genetic diversity. Few of them,
it is further contended, will be able to achieve sustainable economic
development, unless due attention is given to management of the
natural environment, in which plants form such a prominent part.
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 37
We suggest that international organisations concerned with the
two schools of plant conservation that have developed historically
(dealing with conservation of plant genetic resources and wild
plant species respectively) collaborate to advance the discipline of
plant conservation conceptually, making it more useful for coun-
tries like Uganda. Realistic protocols for field implementation will
be required.
Acknowledgements
Many thanks to Dr David Balikowa (Director of Research) for
welcoming a visit to Mbarara Zonal Agricultural Research and
Development Institute (MZARDI) and to Mr. Sedrach Muhangi
(Research Assistant) for a tour of the field collection of bananas.
Professor Maud Kamatenesi Mugisha (Vice Chancellor, Bishop
Stuart University) provided hospitality in Mbarara and transport to
the institute. We are grateful to those who contributed information
during interview for the ‘forests and forestry’ section of the paper.
Comments labelled ‘reported’ are mostly from these sources. They
are Professor John Kaboggoza (former Professor of Forestry, Mak-
erere University, and first Chairperson of the Board of Uganda
Forestry Authority (UFA) 2003e2006), John Kamugisha (Director of
Field Operations for UFA 2004e2006 and earlier Acting Executive
Director), Rachel Musoke (Acting Commissioner, Forest Depart-
ment 1998e1999; Commissioner, Forestry Sector Support Pro-
gramme 2008e2013) and Bill Farmer (Technical Team Leader for
DFID on Uganda Forest Sector Umbrella Programme 1999e2003;
currently Chairman, Uganda Carbon Bureau). Kirsty Shaw of Bota-
nic Gardens Conservation International (BGCI) provided informa-
tion on botanic gardens. Dr Patrick Hamilton assisted with access to
the literature and Mike Lagan helped with computing.
Appendix 1
Detection of human influences on forests in pollen diagrams from
Uganda (See Table 3).
1. High altitude sites
These sites (>2900m altitude) are on the Virunga Volcanoes and
Rwenzori (Livingstone, 1967; McGlynn et al., 2013). Changes in the
abundance of pollen believed to have come from plants growing at
lower altitudes reveal a major reduction in forest at ~1000 CE. A
principal signal of this decline is a fall in Celtis, a pollen type pro-
duced by several species of lowland forest trees. There is no indi-
cation in the pollen diagrams of any major climatic change at
~1000 CE, while contemporaneous peaks in charcoal in the Virunga
sediments are consistent with the theory that forest reduction was
caused by clearance for agriculture. Differences between pollen
diagrams from west- and east-facing valleys on Rwenzori suggest
that reduction in forest was greater to the east of the range
(Hamilton, 1972).
A changed floristic composition of montane forest and wood-
land on the Virunga Volcanoes at ~1000 CE is indicated by increases
in the pollen of Hagenia abyssinica Willd. and Myrica (most likely
from Morella salicifolia (Engl.) Verdc. and Polhill in this context).
Both are small trees of secondary montane woodland, Hagenia
being additionally common in higher altitude montane forest. This
is evidence that people influenced the floristic composition of
forests at some distance from where they were practicing agricul-
ture. The Virunga Volcanoes are unsuitable for agriculture or per-
manent settlement above 2100 m, having very steep slopes, rocky
soils and little surface water.
The dating of forest clearance around Rwenzori relies on more
extensive extrapolation from available radiocarbon dates than is
the case with the Virunga Volcanoes. Nevertheless, there is no
confusion between changes in pollen abundance in the diagrams
indicating forest clearance and changes believed consequent to the
mid-Holocene drying in climate at ~2050e1850 BCE, an event well
marked (at lower levels in the Rwenzori diagrams) by notable in-
creases in Acalypha and Podocarpus.
Pollen diagrams are also available for high altitude sites on Mt
Elgon, actually in Kenya but close to the Ugandan border (Hamilton,
1982, 1987). No episode of deforestation (at any time) is apparent,
though this does not necessarily mean that early forest clearance in
the surrounding lowlands did not occur. Mt Elgon differs from the
Virunga Volcanoes and Rwenzori, which have precipitous slopes, in
having gentle slopes and much more extensive montane forest.
Several species of plants known to be high pollen producers are
abundant in the montane forest, most notably Afrocarpus gracilior
(Pilg.) C.N. Page and Podocarpus milanjianus Rendle (both producing
the pollen type known as Podocarpus). Palynological signs of past
human influence at lower altitudes could thus be masked.
2. Sites in the Rukiga Highlands
These pollen diagrams are for sediments under mires and a lake
(Bunyonyi) at altitudes of 1830e2260 m (Hamilton et al., 1986,
1989; Marchant et al., 1997; Morrison, 1968; Morrison and
Hamilton, 1974; Taylor, 1990). The sites are only 17e34 km from
Mt Muhavura, the nearest of the Virunga Volcanoes. All lie today
within intensively cultivated farmland, except for those above
2000 m, but the whole area is climatically suitable for moist
montane forest. The slopes around one of the higher altitude sites
(Muchoya Swamp, 2260 m) are covered largely by mountain
bamboo (Yushania alpina (K. Schum.) W.C. Lin), a species that
typically forms a zone on wetter mountains in East Africa at
2450e3050 m and which is here dominant at an exceptionally low
altitude (2260e2450 m). It is possible that bamboo has replaced
broad-leafed montane forest following human disturbance
(Hamilton, 1982; Jolly et al., 1997). The other higher altitude site is
Mubwindi Swamp (2100 m), which lies within the moist broad-
leaved montane forest of Bwindi-Impenetrable National Park.
Two of the pollen diagrams (Muchoya, Ahakagyezi) are well
dated for the period of interest here, but no radiocarbon dates are
available for Katenga and Bunyonyi, and Mubwindi shows a hiatus
in sedimentation stretching back several thousand prior to 1 CE.
Rates of sediment accumulation (as measured by sediment thick-
ness) can be highly variable with time in East Africa (Hamilton and
Taylor, 1986; Thompson and Hamilton, 1983), so extrapolation of
intermediate ages from available radiocarbon dates needs to be
approached with caution. A low rate of sediment accumulation
during the earlier (wetter) part of the Holocene is a common
feature.
Pollen diagrams from the Rukiga Highlands provide a more
intimate record of human influence on vegetation than is the case
with the Virunga Volcanoes and Rwenzori. Considered together,
they provide clear evidence of major forest reduction in the past,
believed to be related to agriculture. Higher altitude forest
(2100 m) was less affected than that at lower altitudes and there
may never have been substantial agriculture in the Mubwindi
catchment.
There are signs that soil erosion and degradation accompanied
the agriculture. They include a rise in the pollen ofDodonaea viscosa
Jacq., seen at all sites, but especially prominent at Bunyonyi.
Dodonaea is a shrub typical of degraded soils. Another is an increase
in Typha seen in several of the pollen diagrams. Typha is a wetland
genus known to be responsive to heavy siltation (Lind, 1956). The
volume of soil eroded was large, judging by the great thickness of
sediment (5 m) that accumulated under Lake Bunyonyi since the
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4438
timewhen forest clearance began. This thickness is for the site used
for sediment coring, 0.5 km from the nearest shore and where the
water depth is 40 m. Human influence is likely to have been
responsible for a major change in the vegetation of Muchoya
Swamp. It is dominated today by a sedge (Pycreus nigricans (Steud.)
C.B. Clarke), accompanied by scattered bushes of tree heather (Erica
kingaensis Engl.). A dense layer of fossil Erica wood in the peat,
shows that Pycreus has largely replaced dense Erica scrub, 14C dates
showing that this happened during the 1st millennium CE, a timing
suggestive of a human cause.
The date of forest reduction varied between the sites according
to the available radiocarbon dates. The first signs of disturbance at
Muchoya are at ~225 BCE, intensifying from ~1250 CE, but distur-
bance is only detectable from ~1650 CE at Mubwindi and may
reflect activities at a considerable distance from the sample site.
Ahakagyezi is the most intriguing, with two phases of disturbance
identified, one at ~1700e750 BCE, and another beginning at ~700
CE and continuing to the present, the final clearance of ridge top
forest being at ~1150 CE.
The evidence for the earlier phase of forest disturbance at
Ahakagyezi (~1700e750 BCE) includes small peaks in the pollen of
Bidens sim., Dodonaea viscosa and Rumex (all herbs or shrubs of
open land), as well as Myrica (possibly M. salicifolia) and Nuxia
congesta Comm. ex Lam. (a tree of early forest succession). An initial
interpretation of the pollen diagram (for the upper 10 m of sedi-
ment only, collected in 1982) found evidence of human disturbance
at several levels, including right at the base (dated ~3550 BCE)
(Hamilton et al., 1986, 1989). This interpretation became disputed
once a longer core (22.84m)was collected (in 1984) from a site very
close to that used for the first coring (Taylor, 1990). A longer tem-
poral context for interpreting the properties of the sediments then
became available. As the person responsible for collecting and
analysing the first core, I (AH) now agree with most of the criti-
cisms, but contend that the above-mentioned evidence of very
early forest disturbance at ~1700e550 BCE still stands.
Interpreting the Ahakagyezi diagram is complicated because
possible early human influences must be disentangled from cli-
matic effects associated with the transition to a drier mid-Holocene
climate at 2050e1850 BCE. One of the characteristic indicators of
this transition in pollen diagrams from Uganda is a rise in Podo-
carpus pollen, which, in the case of the Ahakagyezi diagram, started
distinctly earlier (~1950 BCE) than the first phase of human
disturbance suggested above (beginning 1700 BCE). Dating control
for the upper sediment at Ahakakyezi is excellent because the
radiocarbon dates show a very even rate of accumulation of peat
with time and the rate of peat accumulation is the highest known
for Africa (1 m per 500 years). Ahakagyezi is noteworthy hydro-
logically for being a source of the River Nile in two directions, water
flowing out of the swamp at both ends, subsequently passing
through Lakes Victoria and Edward, respectively, and finally
becoming reunited in Lake Albert after travelling their separate
ways for several hundred kilometres.
A decline in the pollen of Alchornea hirtella Benth. was formerly
held to be another indication of very early human disturbance, but
this is an understory tree found today in valleys in lower montane
forest in nearby Bwindi-Impenetrable Forest and it could have been
adversely influenced by the drying in climate. Particular weight
was given in the initial interpretation to high values of inorganic
matter, grass pollen and charcoal at places in the 10 m core,
including at its base. These were interpreted as being related to
slash and burn agriculture, but, with the longer temporal context
now available, it is now accepted that changes in these parameters
have been strongly influenced by changes in the sedimentary
environment, that could have been largely unrelated to agriculture.
3. Crater sediments, Kasenda Volcanic Field
These pollen diagrams are for sediments beneath two small
lakes and a swamp (Kabata) occupying extinct volcanic craters
(Ryves et al., 2011; Ssemmanda et al., 2005; Taylor et al., 1999). The
sites are at altitudes of 1170e1370 m and about 40 km east of those
used for pollen analysis on Rwenzori. All the diagrams show forest
clearance, which is especially obvious and well dated at Kasenda
and Wandakara (occurring at ~900e1000 CE). The same two dia-
grams also show signs of forest regrowth from ~1700 to 1750 CE
(especially from the late 1800s), marked by an initial increase in
Securinega pollen followed by increases in Celtis, Phoenix and other
trees. Securinega pollen may have come from Flueggea virosa (Roxb.
ex Willd.) Voigt, a bush or small tree with edible fruits found on
forest margins. Phoenix pollen is from the wild date palm, a plant
having many uses, and it is possible that these plants were wild-
cultivated. Papyrus (Cyperus papyrus L.) overgrew a lake at Kabata
sometime during the period 400e1400 CE, a date suggestive of a
human cause.
The pollen diagram from Kabata is less precisely dated than
those from Kasenda and Wandakara, and there is an apparent hi-
atus in sedimentation during the early Holocene. The uppermost
sediments were not analysed. Forest disturbance from ~1600 CE is
indicated by a fall in Celtis and a rise in Cyathea. Cyathea is a genus
of tree ferns found in open areas of moist forest. A possible earlier
phase of forest disturbance (poorly dated at sometime between
1350 BCE and 400 CE) is suggested by higher values of Dodonaea
and Pteridium. Pteridium spores come from Pteridium aquilinum (L.)
Kuhn, a fern of open ground, found especially on impoverished
soils. A claim has been made for very early forest disturbance
(predating ~1350 BCE) at Kabata, based largely on high values of
Acalypha (Taylor et al., 1999). Acalypha is a very small and well-
dispersed pollen type, which in pollen diagrams from Rwenzori,
Lake Victoria and Mt Elgon shows increased values associated with
the mid-Holocene transition to a drier climate (~2050e1850 BCE)
(Hamilton, 1987; Kendall, 1969; Livingstone, 1967). Its increase at
Kabata may have had a similar cause.
The cores from Kasenda and Wandakara date back only to 750
CE and 1300 CE respectively. Ricinus pollen, which is present
throughout the pollen diagrams, comes from R. communis (castor
bean plant), a shrub to small tree of disturbed ground and forest
gaps, habitats that could have been encouraged by people. Ricinus
may have been wild-growing or cultivated. Kasenda contains a
greater quantity of tree pollen (Celtis, Ficus, Phoenix, Vepris) than
Wandakara. Forest at Kasenda has received greater protection than
Wandakara over recent decades. It lies within a private estate that
has aimed to retain forest, while the steep slopes around Wanda-
kara are covered by small-scale agricultural plots.
4. Swamp associated with a Later Iron Age settlement at Munsa
Munsa is a Later Iron Age site with large-scale earthworks
constructed at some time between 1400 and 1650 CE, and aban-
doned by 1700 CE (Robertshaw et al., 1997). The site used for
sediment analysis is a small papyrus swamp lying within the
earthworks (Lejja et al., 2005; Lejju et al., 2006). Analyses of the
well-dated sediments at the sample site (pollen, fungal spores,
phytoliths, charcoal), plus archaeological evidence, show forest
clearance at ~1100 CE and the establishment of an economy based
on cereal cultivation, large-scale cattle keeping and iron-smelting.
Analysis of glass beads from archaeological contexts show that
the inhabitants were in contact with exchange networks extending
to South Asia. A papyrus swamp expanded over the sediment site at
about the time when forest was cleared, spreading inwards from
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e44 39
the margins, suggesting that its development was related to human
occupancy. There was some forest recovery from ~1780 CE.
5. Large lowland lakes
A well-dated pollen diagram is available for a core of sediment
from Pilkington Bay, a virtually enclosed bay off Buvuma Island
close to the northern shore of Lake Victoria (Kendall,1969). Buvuma
was largely forested at the time of collection of the core, contrasting
with the nearby mainland which was then covered by a mosaic of
secondary woodland, grassland and agriculture. The quantity of
tree pollen in the sediments starts to decline relative to grass pollen
from ~1 CE and, in absolute terms (number of grains becoming
incorporated per unit time), between 1750 and 1250 BCE. Celtis is
one of the types of tree pollen to decline, just as it does in pollen
diagrams from the Virunga Volcanoes and Rwenzori, but here the
decline begins much earlier.
Wetland vegetation changed at ~1 CE, as shown by increased
amounts of Nymphaea and Typha in the pollen diagram. It has been
suggested that this may be related to a shallowing of the lake
(Kendall, 1969), but an increase in Typha pollen is associated with
forest clearance in the Rukiga Highlands and both of these changes
could have had anthropogenic causes.
A few pollen counts have been made on another core from Lake
Victoria, collected from Kome Channel about 100 km west of Pil-
kington Bay (Kendall, 1969). The pollen diagram broadly confirms
the picture of vegetation change reconstructed from Pilkington Bay.
A core of sediment has been collected from Lake Albert (altitude
619 m) and its upper sediments (those of the age of interest here)
subject to outline pollen analysis (Beuning et al., 1997). A decline in
forest pollen and a rise in grass pollen is evident from 1725 BCE,
considered by the researchers to be due to a drier climate and
perhaps human influence.
Appendix 2
Examples of tropical forest loss and degradation in Uganda since
1970.
1. Budongo Forest
A study of households adjacent to Budongo Central Forest
Reserve (CFR) found that average household income rose signifi-
cantly following transfer of authority over the forest in 2003 from
the Forest Department to the National Forest Authority (NFA)
(Jagger, 2008). The gains were mainly made from the sale of ille-
gally harvested timber and accrued only to richer households.
2. Bugala and Buvuma Islands, Lake Victoria
BIDCO, an oil palm company, was granted permission to plant oil
palms in Mugoye, Banya, Nkoma and Towa CFRs on Bugala Island in
Lake Victoria in 2005 (Tenywa, 2005). Altogether, BIDCO has been
allocated 65 km2 of the islands total area of 290 km2, with a further
35 km2 being made available for an out-grower scheme (Tenywa,
2013). The planting of oil palms was expanded onto Buvuma Is-
land in 2012 through Oil Palm Uganda Limited (OPUL, 90% of which
is owned by BIDCO), its operations resulting in the destruction of
36 km2 of rainforest by 2015 (van Schaik and Tickell, 2015).
3. Bwindi Impenetrable Forest Reserve (National Park from 1993)
A biological and forest utilization survey was carried out in the
forest in 1983e1984, finding large-scale illegal pit-sawing for tim-
ber (an estimated 140e200 illegal pit-sawers operating),
widespread illegal collection of fuelwood, poles and bamboo,
rampant small-scale gold mining and poaching (Butynski, 1984).
Later, further research revealed that 9e12 mountain gorillas had
been killed in the forest over an 18 month period in 1986e1987, a
serious loss considering that this is one of only two sites globally for
mountain gorilla and there were only 115 gorillas in the forest at
the time (Butynski, 1990).
The forest was transferred from the Forest Department to
Uganda National Parks (later Uganda Wildlife Authority e UWA)
in 1993 and much tighter controls over activities in the forest
instigated. An establishment plan prepared for this transfer
received evidence from the Conservation Education Assistants
(CEAs) of a Conservation through Education Project (drawn from
local villages) that there had been three incidents of agricultural
encroachment into the forest on its northern side (Hamilton
et al., 1990). They believed that local forestry officials had
authorised forest destruction for the planting of crops, the idea
supposedly being that they would inter-plant them with valuable
trees. Corruption was suspected. Senior forestry officials from
Kampala intervened and were able to stop one of the
encroachments.
Relationships between the new park and the local people were
poor at first, with fires set or not extinguished in the forest and
threats made to kill the gorillas (Hamilton et al., 2000). Three
schemes were then instituted to provide benefits to adjacent
communities and involve them in park management, these being
agreements on the controlled harvesting of certain resources in the
park (Cunningham, 1996; Wild and Mutebi, 1996, 1997), the receipt
of some revenues from tourism and establishment of a trust fund
for community development. The situation eventually stabilised.
Based on analysis of satellite imagery, the National Biomass Survey
reported in 2002 that there was no evidence of forest depletion in
the 31,046 ha of forest then present in the national park (total area
32,019 ha) (Drichi, 2002).
4. Forests in Mpigi District and other forests near Kampala
A sample of 9 forests lying in Mpigi District (20e70 km west of
Kampala) showed a 62% decline in biomass and 74% decline in tree
density between 1994/1995 and 1999/2000, attributed to tree
harvesting for firewood and timber, and clearance for agriculture
(Banana et al., 2007). Not all forests suffered equally. Mpanga CFR,
classified as a nature reserve, was little affected, benefitting from
relatively high level of staffing through funding from the European
Union. One other government-owned forest that did well was
Kizzikibbi, where negotiations between government officials and
the local community resulted in the development and enforce-
ment of strict rules over harvesting. One of the two private forests
included in the survey (Namungo) was also well managed. The
forest owner is said to have worked closely with the village
council and neighbouring community to develop agreements that
effectively regulated harvesting. The National Biomass Study re-
ported in 2002 that, of the total area of Mpanga CFR (1012 ha),
only 43 ha had been deforested and 14 ha degraded (Drichi, 2002),
confirming that it was substantially intact. However, a permanent
plot monitored over 40 years in the forest revealed several cases of
illegal tree felling, including of Antiaris toxicaria Lesch. and Fun-
tumia africana (Benth.) Stapf for carving into drums (Taylor et al.,
2008).
A return survey revealed that 11 out of 22 forest patches lying
within a distance of 35 km of Kampala disappeared between 1990
and 2010 (Bulafu et al., 2013). Three of the surviving forests were
government-owned (one belonging to the NFA and the other two to
research institutes), four belonged to churches, three to individuals
and onewas communal (a sacred forest). However, all the surviving
A.C. Hamilton et al. / Plant Diversity 38 (2016) 23e4440
forests, except those belonging to the government, had become
severely degraded, the causative factors considered to be selective
logging and fragmentation effects (increased mortality of exposed
large trees near forest edges).
5. Forest Reserves in Busoga
Half of Bukaleba CFR was transferred to the Ministry of Animal
Resources in 1975, the remaining part becoming heavily
encroached (Hamilton, 1984). It was reported that South Busoga
CFR became heavily encroached after 1975, about half of its
163 km2 being lost by 1982 (Hamilton, 1984). The National Biomass
Study reported in 2002 that, of the total area of Bukaleba CFR as
then constituted (9536 ha), 1293 ha had become deforested and
231 degraded (Drichi, 2002). The equivalent figures for South
Busoga CFR (total area 16,107 ha) were 493 ha (deforested) and
12,539 ha (degraded).
6. Kibale and Kisangi Forest Reserves (Kibale a National Park from
1993)
Schemes for the resettlement of people from densely populated
Kigezi in southwest Uganda have existed since the 1930s. One area
chosen for resettlement has been land close to these two forest
reserves, within one of which (Kibale) encroachment by the
resettled people is reported to have started in 1971e1972 and in
Kisangi a year or two later (Hamilton, 1984). All of Kisangi was
reported to have been felled by 1982. A ground survey of southern
Kibale in 1980 found that about 7000 people had settled in the
forest reserve, 97 km2 of which had become disturbed by 1982 (Van
Orsdol, 1983). The National Biomass Study reported in 2002 that, of
the total area of rainforest (49,447 ha) in Kibale National Park (total
area 74,396 ha), 5351 ha had become degraded. Of that part of
Kisangi that has remained as a CFR after creation of the national
park (481 ha), 344 ha were classified as deforested and 98 ha as
degraded.
7. Mabira Forest Reserve
Encroachment was not regarded as a serious problem before the
1970s (Earl, 1971). Forest protection started to collapse in the mid-
1970s, when a government minister is alleged to have encouraged
settlement in the forest reportedly in response to the governments
call to ‘double agricultural production’ following expulsion of
‘Asians’ from the country in 1972. There were many reports of
agricultural encroachment and uncontrolled charcoal burning in
the forest by 1982, the forest being described as looking like a
hollow shell from the air (Hamilton, 1984). The National Biomass
Study reported in 2002 that, of the total area of Mabira CFR
(29,566 ha), 1215 had become deforested and 7099 degraded
(Drichi, 2002).
The government sought to degazette 7100 ha of the forest in
2007 to clear for the growing of sugarcane by the Sugar Corporation
of Uganda (Veit, 2010). This became a major political issue in
Uganda with demonstrations held in Kampala (resulting in some
fatalities) (Nakkazi, 2011). Concern for conservation was expressed
internationally (BirdLife International, 2008). The King of Buganda
(Kabaka) declared that he would find an equivalent area of non-
forested land elsewhere for the sugar estate to prevent the for-
ests loss. Theats to Mabira continue.
8. Mt Elgon Forest Reserve (National Park from 1993)
Encroachment started at several places during the 1970s,
most seriously on the western side where 82 km2 of forest was
reported to have been lost by 1982, involving about 5000e7000
farmers (Hamilton, 1984). Cultivation was then extending in
places up to the bamboo zone (lower altitudinal limit 2450 m),
which itself was being heavily grazed by cattle. At Bumbo in the
southwest, an old man was given a temporary permit in the
1960s to reside and cultivate in the forest, together with his small
immediate family. By 1980 the ‘family’ had expanded to 230
people and the encroachment was out of control. Satellite images
showed that a slice of forest running along part of the northern
boundary had become lost by 1982 (Carvalho, 1982). This is an
area that had been affected by ethnic disturbances in the pre-
ceding years, resulting in difficulties in administration for the
Forest Department.
A study of changes in forest extent on Mt Elgon between 1973
and 2009, based on comparison of satellite images and ground
survey, found that 25% of the forest had been destroyed illegally
between 1973 and 1988, fuelled by land grabs for agriculture
(Sassen, 2014; Sassen et al., 2013). Greater discipline was restored
when the reserve was made a national park in 1993, resulting in
some vegetation regrowth, though hampered by continuing illegal
collection of firewood (up to >1 km inside the park boundary). The
National Biomass Study reported in 2002 that, of the total area of
forest on Mt Elgon (55,826 ha), 29,606 had become degraded
(Drichi, 2002). This figure for the area of degraded forest is com-
parable with that of 25,000 ha, the size of the area allocated for a
tree planting scheme to gain carbon credits under an agreement
reached between the FACE Foundation in the Netherlands and UWA
in 1994 (White and Wanyama, 2006). Exceptionally, deforestation
has continued in the southeastern sector, especially since 2005,
when multi-party politics resumed in Uganda and rival electoral
candidates are reported to have competed with ‘giving away’ land
to farmers (Sassen, 2014).
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