全 文 ：Seasonal Dynamics of Energy Return Through Litterfall of A Mixed
Forest of Chinese Fir and T.odorum＊
Yang Yusheng
＊＊　Chen Guangshui　He Zongming
Li Xiufang　Chen Yinxiu
ABSTRACT　Based on the measurement of monthly litterfall and their gross caloric values , the seasonal dynam-
ics of energy return through litterfall were determined in a pure and a mixed T .odorum (Tsoongiodendron odorum
Chun)forests with Chinese fir(Cunninghamia lanceolata(Lamb.)Hook.)in Sanming , Fujian Province.Annu-
al energy return through litterfall was estimated as 12.648×106J·m-2 for the mixed forest , being 4.2%higher
than that of the pure forest , and a large proportion of the energy return comprised leaf litter.The conversion effi-
ciency of solar radiation energy into litterfall was 0.56% for mixed forest and 0.54%for pure forest , respectively.
The monthly energy flux in litterfall of Chinese fir showed a three-apex curve , peaked in March , August and De-
cember , respectively , which was similar to that in various fractions of leaf , twig , flower and fruit litter.The con-
sistency in monthly patterns among different litter fractions of Chinese fir was attributed to their solid connections
all the while.The monthly energy flux in litterfall of T.odorum culminated in January , May and August , the
same was true for its leaf and twig litter.However , energy flux in flower litter only occurred during March to May
and that in fruit litter appeared in January andMarch.The monthly dynamics of energy flux through litterfall of the
two forests were both determined by their respective litterfall pattern of Chinese fir.Seasonal energy flux in litter-
fall for both mixed and pure forests followed the sequence of spring>winter>summer>autumn , but fluctuations
in the former were less distinct than those in the latter.
KEYWORDS　Chinese fir , mixed forest , litterfall , energy flux , seasonal dynamics
　Yang Yusheng , Chen Guangshui , He Zongming , Li
Xiufang , Chen Yinxiu.Department of Resource and
Environment , Fujian Agriculture and Forestry Universi-
ty , Nanping 353001 , P.R.China
＊＊
Corresponding Author.Post-doctoral Station of Biolo-
gy , Xiamen University , Xiamen 361005 , P.R.China
Tel.:86-599-8504990 Fax:86-599-8500504 Email:ff-
cyys@public.npptt.fj.cn
＊
Supported by the Foundation of Post-doctoral Research
of China (2000F004)
Received March 12 ,2001
1　Introduction
　Soil degradation caused by continuous mono-cul-
ture with Chinese fir has received considerable at-
tention , and mixed Chinese fir with broad-leaved
forest has been widely regarded as one of the most
effective ways to maintain long-term productivity of
Chinese fir plantations (Yu 1996 , Sheng 1992 ,
Yang 1998).Introduced broad-leaved tree species ,
such as Sassafras tzumu Hemsl , Michelia macclurei
Dandy , Phoebe bournei (Heml.)Yang , Cinnamo-
mum camphora (L.)Presl , Choerospondias axil-
laris (Roxb.) Burtt et Hill , Altingia gracilipes
Hemsl., Elaeocarpus decipiens Hemsl., Schima
superba Gardn.Et Champ., Manglietia yuyuanen-
sis Law , Michelia maudiae Dunn , Tsoongiodendron
odorum Chun , Paulownia fortunei (Seem.)
Hemsl.etc into pure stands of Chinese fir , was re-
ported of advantages to soil fertility (Yu 1996 ,
Yang 1998).
Litterfall plays a fundamental role in the forest
ecosystem process;it is essential to the organic pro-
duction-decomposition cycle and is a primary means
of dry matter , nutrient and energy transfer from
26
Forestry Studies in China 3(1):26 ～ 31
standing crop to forest soil.Some have reported on
the amount and seasonal dynamics of production and
nutrient transfer through litterfall in mixed forest of
Chinese fir(Chen et al.1988 , Liao et al.2000),
but few was done on the dynamics of energy flux
concomitantly.Organ matter income through litter-
fall in forest soil represents a source of energy to
make a drive for soil microbes andmicrofauna activ-
ity , of which the soil fertility was ameliorated during
the course.
　This study was a part of larger project to evaluate
the benefit of mixed Tsoongiodendron odorum with
Chinese fir in relation to Chinese fir pure stand in
Sanming of south China , based on the measure-
ments of stand biomass , productivity , nutrient con-
centrations , caloric values and soil fertility.In this
paper , we addressed the difference between energy
production and energy flux through litterfall of the
two forests.
TABLE 1　Annual energy flux in various litter fractions
Litter fractions
Mixed forest Pure forest
Chinese fir T.odorum Chinese fir
Mass (g·m-2) Energy×106 (J·m-2) Mass (g·m-2) Energy×106 (J·m-2) Mass (g·m-2) Energy×106 (J·m-2)
Leaf 255.0 5.541 89.9 1.803 303.4 6.645
Twig 115.4 2.501 14.7 0.293 127.2 2.634
Flower 6.8 0.149 1.7 0.032 9.5 0.207
Fruit 40.7 0.879 2.3 0.045 62.1 1.351
Subtotal 417.9 9.070 108.6 2.173 502.2 10.837
Residue 67.5 1.405 64.6 1.307
Total 593.8 12.648 566.8 12.144
TABLE 2　Seasonal changes of energy flux through litterfall in the mixed and pure forests(×106 J·m-2)
Forests Spring Summer Autumn Winter Total
Mixed forest 4.774 2.304 2.101 3.469 12.648
Pure forest 5.143 2.605 0.634 3.762 12.144
2　Site description
　The study sites are located in Xiaohu work area of
Xinkou Experimental Forestry Farm of Fujian Agri-
cultural and Forestry University , Sanming , Fujian
Province(26°11′30″N , 117°26′00″E).This area
has a sub-tropical monsoonal climate with an annual
temperature of 19.1℃, an annual precipitation of
1 749mm , an annual transpiration of 1 585.0mm ,
an annual relative humidity of 81%, and a frost-
free period of around 300 days.The soil is red soil
derived from sand-sale.The mixed forest of Chinese
fir and T.odorum , and pure forest of Chinese fir ,
were both established with seedling in 1973 , with a
planting density of 3 000 stems per hm
2.The mixed
pattern is strip spacing , with three rows of Chinese
fir spaced by one row of T.odorum.At the time of
survey(at age 27), the pure stand had a density of
1 100 stems per hm
2 , with a crown density of 0.80 ,
and a coverage of 95% for undergrowth.The mean
tree height and D.B.H were 19.2m and 24.0 cm ,
respectively.The mixed stand had a density of 907
stems per hm
2
for Chinese fir and 450 stems per hm
2
for T.odorum.The mean tree height and D.B.H
were 22.5m and 24.3 cm for Chinese fir , and were
18.0 m and 17.4 cm for T.odorum , respectively.
The crown density was 0.95 and the undergrowth
coverage was 80%.
3　Methods
　Three 0.04 hm2 marked plots were established in
either of the two stands.Fifteen 1.0 m2 litter traps
27Yang Yusheng et al.
were randomly located in one plot of each stand.
They were emptied at monthly intervals during Janu-
ary 1999 to January 2000 , sorted into leaves ,
branches , fruits , flowers , residues , and then oven-
dried at 80℃ to constant weight.Litter samples for
caloric determination were oven-dried and ground.
Gross caloric values were measured by using an
HWR-15 auto-recording calorimeter.Ash content
was determined using a dry cineration method (Lin
et al.1996).
4　Results and discussion
4.1　Annual energy flux through litterfall
　In a forest ecosystem , litterfall not only returns a
lot of nutrient from trees to soil , but also inputs a
mass of energy to soil ecosystem.Annual energy
flux through litterfall of mixed forest was estimated
as 12.648×106 J·m-2 , being 4.2% higher than
12.144×106 J·m-2 of pure forest , of which the lit-
ters of Chinese fir and T.odorum and residues ac-
counted for 71.7%, 17.2% and 11.1%, respec-
tively.In the pure forest , the litters of Chinese fir
and residues occupied 89.2%and 10.8% of annu-
al energy flux.Leaf litters constituted 61.1% and
61.3% of annual energy flux through litterfall for
Chinese fir both in the mixed and pure forests ,
compared with a contribution of 83.0% for T.
odorum in the mixed forest.The second were twig
litter followed by fruit litter , while the contributions
of flower litter were less than 2%.It indicated that
leaf litter accounted for a largest proportion of annu-
al energy flux , especially for that of T.odorum.
Annual energy flux through litterfall in these two
forest was lower than that in sub-tropical rain forest
(16.811×106 J·m-2·a-1)and mangrove forest of
Fujian(18.359×106 J·m-2·a-1), but higher than
castanopsis eyrei forest in Wuyi Mountain(7.679×
10
6
J·m-2·a-1)(Lin et al.1995 , Lin et al.
1990 , Lin et al.1996).
　For the purpose of comparison of annual energy
flux through litterfall among different climatic zones
and different forest types , the energy conversion ef-
ficiency of solar radiation energy into litterfall was
estimated as the ratio of annual energy flux through
litterfall to the photosynthetic active radiation
(PhAR)(Lin et al.1990).Based on the solar ra-
diation energy (SRE)measured in 1999 in this area
(4 789 800 kJ·m-2·a-1), PhAR was estimated as
2 251 206 kJ·m-2·a-1(using the formula:PhAR
= SRE×0.47).Thus , the conversion efficiency
was estimated as 0.56 and 0.54% for the mixed
and pure forest , respectively , values lower than that
of sub-tropical rain forest (0.81%)and Mangrove
forest(0.88%)in Fujian Province , but significant-
ly higher than that of Castanosis eyrei forest in Wuyi
Mountains (0.17%), rain forest in Ivory Coast
(0.21%), and tropical forests in Puerto Rico
(0.15%～ 0.46%)(Lin et al.1996).
4.2　The monthly changes of energy flux thro-
ugh litterfall of mixed and pure forests
FIGURE 1　Monthly changes in energy flux through
litterfall of mixed forest
　It can be seen from Figure 1 that the annual ener-
gy flux through litterfall of Chinese fir in the mixed
forest culminated in March , August and December ,
with a highest value appeared in March.The same
was true for that of Chinese fir in the pure forest ,
whereas that of T.odorum of mixed forest peaked
in January , May and August , with a lowest value
occurred in December.The energy flux in residue of
28 Forestry Studies in China ,Vol.3 ,No.1 ,2001
mixed forest peaked inMarch and August while that
of pure forest in December , though the monthly
fluctuations were less significant.The monthly pat-
tern of energy flux through litterfall in the pure and
mixed forests was approximately consistent with that
of their respective Chinese fir therein (Figure 2).
In subtropical China , most evergreen conifers ini-
tiate their activities in March when most aged leaves
was replaced by fresh leaves , thus a largest quantity
of litterfall occurred at this time.August is often a
dry period with a high temperature in this area ,
when substantial leaves are burned and dropped off
due to lack of water.In December most evergreen
trees shatter , being subjected to a low temperature.
Whereas the pattern is not true for T.odorum ,
which is related to its inherit characteristics that dif-
fered from most evergreen conifers.
FIGURE 2　Monthly changes in energy flux
through litterfall of pure forest
4.3　The monthly changes of energy flux in va-
rious litter fractions
　The patterns for monthly change of energy flux in
various litterfall components of Chinese fir were sim-
ilar to those of total litterfall , with three peaks oc-
curred inMarch , August and December.The accor-
dance among energy fluxes in various fractions of lit-
terfall is largely attributable to the tight association
between various components.Chinese fir blossom in
April and seed in October , but their flowers and
cones can remain on twigs for a relatively long time ,
FIGURE 3　Monthly energy flux in various litter
fractions of Chinese fir in mixed forest
FIGURE 4　Monthly energy flux in various litter
fractions of Chinese fir in pure forest
FIGURE 5　Monthly energy flux in various litter
fractions of T.odorum in mixed forest
and the flower litter and cone litter could occur dur-
29Yang Yusheng et al.
ing the whole year.
　For T.odorum , the monthly energy flux in leaf
litter and twig litter culminated in January , May and
August , both minimized in December.The energy
flux in flower litter only occurred from March to
May , and that of fruit litter in January and March.
The florescence of T.odorum was in March and
April and no flower litter occurred after May.T.
odorum fruit during September to October , but the
time of fruits fall remits to January andMarch in the
second year.
　The energy flux in litterfall fluctuated very much
among seasons and was in the sequence of spring>
winter>summer>autumn for both forests , with the
maximum difference of 2.673×106 J·m-2 for the
mixed forest and 4.509×106 J·m-2 for the pure
forest.Compared with the mixed forest , the energy
flux in autumn in the pure forest was rather low.
The seasonal patterns were similar to the result from
a 22-year-old Chinese fir stand (Tian et al.
1989), but differed from Fu et al.(1990), where
the peaks of seasonal litterfall showed happened
both in spring and in autumn.
5　Conclusions
　The annual energy flux through litterfall of mixed
forest was up to 12.648×106 J·m-2 , being 4.2%
higher than that of pure stand , and the contributions
of Chinese fir , T.odorum and the residue were
71.7%, 17.2% and 11.1%, respectively.Of the
energy flux in tree litterfall , the majority comprised
leaf litter.The conversion efficiency of the solar ra-
diation energy into litterfall was 0.56% and
0.54%, respectively.Due to the close association
with each other , the pattern for monthly energy flux
in leaf , twig , flower and fruit litter of Chinese fir
was very similar , with three peaks occurred in
March , August and December for both forests.For
T.odorum , the energy flux in leaf and twig litter
was similar to that in total litterfall which showed a
three-apex curve , and peaked in January , May and
August , while that in flower litter only occurred
from March to May and that in fruit litter in January
and March.The monthly pattern of energy flux in
total litterfall of both two forests was consistent with
that of their respectively Chinese fir therein.Both
forests showed a seasonal pattern of spring>winter
>summer >autumn for energy flux of litterfall ,
though the fluctuation in the mixed forest were less
than in the pure forest.
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杉木 、观光木混交林凋落物能量归还量初步研究
杨玉盛　陈光水　何宗明　李秀芳　陈银秀
(福建农林大学资源与环境系 ,南平 353001)
摘要　通过对杉木 、观光木混交林及杉木纯林群落凋落物的能量年归还量及能流的季节变化进行研
究 ,结果表明 ,混交林凋落物的能流量达 12.648×106J·m-2 ,比纯林的高 4.2%;在各目的树种凋落物
组成中 ,落叶能流量均占大部分;混交林和纯林群落太阳能进入凋落物的转化效率分别为 0.56%和
0.54%.混交林和纯林中杉木凋落物能流一年中分别在 3 ,8和 12月出现 3个高峰 ,其中落叶 、落枝 、落
花和落果能流的月变化与之相似 ,这与杉木的小枝整体凋落方式有关;混交林中观光木凋落物能流在
1 ,5和 8月出现高峰 ,其中落叶和落枝能流月变化与之相似 ,但落花能流仅出现在 3 ～ 5月 ,而落果仅
发生在1月和 3月.各群落凋落物能流月变化模式与其中杉木凋落物能流变化模式基本一致.混交林
和纯林凋落物能流的季节变化为春季>冬季>夏季>秋季 ,但混交林凋落物能流量季节间变动小于
纯林的.
关键词　杉木 ,混交林 ,凋落物 ,能量流动 ,季节动态
31Yang Yusheng et al.