全 文 ：第 25 卷第 12 期
2005 年 12 月
生　　态　　学　　报
A CTA ECOLO G ICA S IN ICA
V o l. 25,N o. 12
D ec. , 2005
人为干扰下南亚热带厚壳桂种群分布格局
王峥峰1, 高三红2,M ary Jo W. Godt3, 彭少麟2, 傅声雷1
(1. 中国科学院华南植物园, 广东省数字植物园重点实验室, 广州　510650; 2. 中山大学生命科学学院, 广州　510275;
3. D epartm ent of P lan t B io logy, U niversity of Geo rgia, A thens　30602, U SA )
基金项目: 国家自然科学基金资助项目 (30300055) ; 广东省自然科学基金资助项目 (031264) ; 瑞典 IFS 基金资助项目 (N o. D ö323921) ; 中国科学
院华南植物园所长基金资助项目
收稿日期: 2004211221; 修订日期: 2005203227
作者简介: 王峥峰 (1973～ ) , 男, 江苏南京人, 博士, 主要从事分子生态、种群生态学研究. E2m ail: w zf@ scbg. ac. cn
Foundation item: N ational N atural Science Foundation of Ch ina (N o. 30300055) , N atural Science Foundation of Guangdong P rovince (N o.
031264) , In ternational Foundation of Science , Sw eden (N o. D ö323921) , Fondation of H ead of South Ch ina Bo tan ical Garden, Ch inese
A cadem y of Sciences
Rece ived date: 2004211221; Accepted date: 2005203227
Biography:WAN G Zheng2Feng, Ph. D. , m ain ly engaged in mo lecu lar eco logy and population eco logy. E2m ail: w zf@ scbg. ac. cn
摘要: 南亚热带季风常绿阔叶林是华南地区典型代表植被类型。由于人为干扰, 其现存面积日益减少。为加强保护, 对这一植被
类型中的演替顶级种厚壳桂 (C ryp tocary a ch inensis)种群在人为干扰下的数量和分布格局进行了研究。研究地点设在广东省广
州市萝岗长龙村村边。此林为南亚热带次生季风常绿阔叶林, 受当地农民的干扰很大。样方面积是 50×100 m 2。研究结果表明,
和较少受人为干扰的种群相比, 这一种群趋于随机分布, 特别是小树和幼苗阶段的个体。种群数量的调查研究表明这一种群幼
苗库明显不足, 表明人为干扰对这一种群的更新影响较大。认为在加强保护区等建设的同时, 对分散在各地点的典型植被类型
要进行保护, 特别是加强对周围居民的保护意识教育。
关键词: 分布格局; 人为干扰; 厚壳桂; 生活阶段; 幼苗库
文章编号: 100020933 (2005) 1223289205　中图分类号: Q 948. 15　文献标识码: A
C ryp toca rya ch inens is spa tia l d istr ibution pa ttern s caused by human d isturbance
in the lower subtrop ica l m on soon evergreen broad- leaved forest
W AN G Zheng2Feng1, GAO San2Hong2, M ary Jo W. Godt3, PEN G Shao2L in2, FU Sheng2L ei1 　 ( 1.
Guang d ong K ey L abora tory of D ig ita l B otan ica l Gard en, S ou th Ch ina B otan ica l Gard en, Ch inese A cad emy of S ciences, Guang z hou 510650,
Ch ina; 2. S chool of L if e S ciences, S un Y a t2S en U niversity , Guang z hou 510275, Ch ina; 3. D ep artm en t of P lan t B iology , U niversity of Georg ia,
A thens, 30602, U SA ). A cta Ecolog ica S in ica , 2005, 25 (12) : 3289～ 3293.
Abstract: L ow er sub trop ical monsoon evergreen b road2leaved fo rests are of h igh conservat ion sign ificance in Sou th Ch ina.
Because of hum an activit ies, the fo rest has been largely destroyed; the rem ain ing fragm en ts are now m ain ly in several p ro tected
reserves. To fu rther p ro tect th is fo rest ou tside the reserves and to study hum an influences on it, w e analyzed the spat ia l
pat tern of C ryp tocary a ch inensis, a dom inan t tree in the fo rest near Changlong village, Guangzhou, Ch ina. Compared w ith low
hum an distu rbance fo rests, in w h ich C. ch inensis w as clumped, w e found that trees w ere random ly distribu ted, especially the
young life stages. H um an activit ies in th is fo rest have also led to the decline of the C. ch inensis seedling bank, suggest ing that
the popu lat ion is regenerat ing badly.
Key words: spat ia l pat tern; hum an distu rbance; C ryp tocary a ch inensis; life stages; seedling bank
　　Today, a grow ing num ber of in ternat ional agreem en ts regarding b iodiversity and sustainab le developm en t stress the
impo rtance of p reserving typ ical eco system s and hab ita ts[1～ 3 ]. How ever, eco system s do no t consist simp ly of physical featu res.
T hey include b io logical o rgan ism s in teract ing w ith the physical environm en t. T herefo re, eco system s can no t be p reserved
w ithou t conservat ion of the b io ta.
M o reover, a lthough estab lish ing reserves that encompass rep resen tat ive examp les of eco system s is a good conservat ion
stra tegy, reserves them selves can no t be expected to p reserve all the b iodiversity. Because m any o rgan ism s (e. g. , b irds and
insects) move betw een differen t areas, it is un likely that a few reserves w ill be ab le to sustain popu lat ions of all species.
T herefo re, it is impo rtan t to p reserve hab ita ts ou tside reserves, even if they are sm all in area.
L ow er sub trop ical monsoon evergreen b road2leaved fo rests are found in the trop ical2sub trop ical transit ion zone in sou thern
Ch ina (22—24°N ) , near the T rop ical of Cancer. In con trast to sim ilar la t itudinal areas elsew here, w h ich are almo st all dry o r
sem idry lands, un ique, luxu rian t sub trop ical fo rests are w ell developed in sou thern Ch ina because of the areas p rox im ity to the
Pacific O cean. M uch of th is fo rest eco system has already been destroyed. How ever, cu rren t overexp lo ita t ion and the
environm en tal deterio rat ion that is accompanying econom ic developm en t have m ade condit ions even mo re serious. R ecen t
inven to ries indicate that the fo rest has been reduced to a few iso lated patches, w h ich are cu rren t ly p ro tected because of their
key ro le in the low er sub trop ical eco system. In addit ion, these fo rests suppo rt b io t ic diversity by p roviding food fo r b irds,
in sects, and m amm als[4 ].
O u r know ledge of hum an influences on the low er sub trop icalmonsoon evergreen b road2leaved fo rest is st ill incomp lete[5 ].
O u r ob ject ive here is to docum en t changes b rough t abou t by hum an activit ies on the spat ia l pat tern of C ryp tocary a ch inensis
(H ance) H em sl. , a dom inan t tree in th is fo rest.
C ryp tocary a ch inensis is a common evergreen tree w idely distribu ted in low er sub trop ical sou thern Ch ina, grow ing up to 20
m eters h igh. It is m esophyte, clim ax species in low er sub trop ical monsoon evergreen b road2leaved fo rest. C. ch inensis is a
half2shade to leran t species, h igh dense canopy w ill p reven t its regenerat ion [6 ].
H um an activit ies impo se spat ia l pat tern ing on fo rests that is often differen t from that of natu ral comm un it ies. Fo r
examp le, large2scale p lan t ing of econom ically impo rtan t trees creates homogeneous landscapes, w h ich m ay facilita te the sp read
of pests and pathogens[7 ]. O ther hum an activit ies, such as the expansion of agricu ltu re land and u rban and infrastructu re
developm en t, lead to fo rest fragm en tat ion, w h ich enhances environm en tal heterogeneity, iso lates popu lat ions and reduces their
size [8 ]. O n a local scale, hum an2act ivit ies m ay indirect ly affect the distribu t ion of fo rest species by affect ing the movem en ts of
po llinato rs, seed dispersers, and herb ivo res. Fo r examp le, in Yellow stone N ational Park, w ildlife m anagem en t po licies
affected the movem en t, behavio r and b row sing pattern s of elk w h ich subsequen tly changed the distribu t ion of aspen (P op u lus
trem u loid es) [9 ]. Such indirect influencesm ay also occu r th rough alterat ion of the physical condit ions of fo rests, such as changes
in so il characterist ics[10 ] and fire frequency[11 ].
1　M ater ia ls andM ethods
1. 1　Site D escrip t ion
T he study site is near the village of Changlong (23°06′N , 113°18′E, 80 m a. s. l. ) , no rtheast of Guangzhou, Guangdong
P rovince, Ch ina [12 ]. T he m ean annual temperatu re is 2119 ℃, and the m ean annual p recip ita t ion is 1738 mm , w h ich falls
m ain ly betw een A p ril and O ctober. T he so il type is la terit ic2red earth [12 ].
T h is fo rest w as in tensively logged tw ice in the 1940’s and 1950’s (Yu ZY, personal comm un icat ion) ; then it w as p ro tected
by the local peop le un til abou t 1995[12 ]. How ever, in June 2003, the typ ical fo rest persisted in an area of on ly abou t 1 ha (F ig.
1). N ew ly cu t stump s indicated frequen t logging in the fo rest. L ocal peop le also raise ch ickens in the fo rest. Ch ickens k ill t ree
seeds and seedlings by grazing and tramp ling. T hey also destroy the lit ter and su rface layer of the so il, thereby p reven ting the
germ ination and estab lishm en t of seedlings.
Because of hum an activit ies, the herbaceous stra tum of th is fo rest is typ ically sparse. Canopy trees in the fo rest are
scat tered and include Castanop sis hy strix DC. , E nd osp erm um ch inensis Ben th. , E ng elhartiia ch ry solep is H ance, C ryp tocary a
concinna H ance, C. ch inensis, M ach ilus ch inensis (Champ. Ex Ben th. ) H em sl. , and Canth ium d icoccum (Gaertn. ) M err.
1. 2　D ata Co llect ion and Spatia l Stat ist ics
A ll C. ch inensis w ere m apped in a 50 m × 100 m p lo t in June 2003 (F ig. 1). Individuals w ere reco rded fo r their diam eter
at b reast heigh t (d bh ) and heigh t. Individuals < 2. 5 cm dbh w ere on ly reco rded fo r heigh t. T rees w ere classified in to life
stages fo llow ing W ang et a l[6 ]. Som e p reviously cu t trees had re2sp rou ted from their stump s o r stem s. Because their age cou ld
no t be determ ined, these trees w ere no t included in the life stage classificat ion.
Because of hum an activit ies, the study p lo t w as very heterogeneous. C ryp tocary a ch inensis w ere densest on the low er slope
0923　 生　态　学　报 25 卷
(F ig. 1). To analyze the spat ia l pat tern, sm aller homogeneous subp lo ts w ere defined using local density[13 ]. L ocal density in
circles of radiu s 12. 5 m w as determ ined at each node of a 10 m × 10 m system atic grid. T he low ess m ethod ( local w eigh ted
scat ter2p lo t smoo th ing) w as then used to p redict the values of the local density function at each node of a 10 m × 10 m
system atic grid. T he local regression w as compu ted over the eigh t nearest neighbo rs to m in im ize the m ean smoo th ing erro r.
T hen, tw o app rox im ately homogeneous subp lo ts w ere delineated by in terpo lat ion of the p redicted values (F ig. 1).
F ig. 1　M ap of C ryp tocary a ch inensis in a 50m ×100m p lo t of low er
subtrop ical evergreen broad2leaved fo rest near the village of
Changlong, Guangzhou, Guangdong P rovince, Ch ina. Two sm aller
subp lo ts are divided by the do tted lines
　　R ip ley’s L ( t) 2funct ion analysis w as used to characterize the
spat ia l pat tern s of C. ch inensis in each of the homogeneous
subp lo ts[6 ]. B riefly, w hen L ( t ) = 0, the spat ia l pat tern is
random at the scale of t; w hen L ( t) < 0, the distribu t ion is
un ifo rm; and w hen L ( t) > 0 the distribu t ion is clumped. T he
sign ificance of the observed pattern sw as tested (again st the nu ll
hypo thesis of Po isson dispersion ) by random izat ion tests w ith
10, 000 sim u lat ions. A ll calcu lat ions and the con tou r lines w ere
perfo rm ed w ith AD E24[14 ]. Spat ia l analyses w ere no t conducted
fo r L ife Stages IV and V because there w ere too few individuals.
2　Results and D iscussion
T he spatia l distribu t ion of the differen t C. ch inensis life
stages are p resen ted in F ig. 2. R ip ley’s L ( t) analysis indicated
that C. ch inensis w ere random ly distribu ted at large distances,
bu t sign ifican tly clu stered at sm all and in term ediate distances,
excep t fo r L ife Stage I. T he spatia l pat tern fo r L ife Stage I
tended to be random , excep t at the largest distance. T hese
random pattern s ( especially fo r young life stages ) w ere in
con trast to w hat w e found in studies of low hum an distu rbance
fo rests, in w h ich all life stages w ere clu stered at almo st all
distances[6 ].
A ccoding to Cai et a l [12 ] , th is fo rest w as st ill w ell p ro tected
ten years ago. Bu t since then, its condit ion has changed great ly.
T he impact of hum ans on C. ch inensis can be seen in m any
w ays.
F irst, the fo rest is easily accessed from the village and it
has frequen tly been sub ject to hum an distu rbances like logging.
A lthough the num ber of C. ch inensis trees that have been logged canno t be determ ined, tree re2sp rou ts w ere abou t 25% the
to tal individuals, bu t few er than one2th ird of cu t trees w ere in L ife Stage Ì and Í (a size su itab le fo r firew ood o r bu ilding).
How ever, as a p revious study repo rted [12 ] and from o ther reco rds (Yu ZY, personal comm un icat ion) , the absence of large trees
m ay be caused by in tensive logging in the past. P resen tly on ly five large trees (L ife stage V ) rem ained, tw o w ith in the study
p lo t, and th ree ou tside it (F ig. 1).
Second, the influence of hum an activit ies on the life stage distribu t ion can be seen in the absence of younger life stages
(F ig. 1). P reviously, there w as a 1200 m 2 study p lo t in th is fo rest [12 ] , in w h ich a 100 m 2 subp lo t w as used to invest igate young
C. ch inensis w ith heigh ts betw een 0. 5 m and 1. 5 m. A lthough the subp lo t w as sm all, there w ere 13 C. ch inensis individuals of
th is size in the subp lo t. If demograph ic trends had con tinued, w e w ou ld have expected app rox im ately 650 individuals w ith such
heigh ts in ou r p lo t. How ever, the to tal num ber of individuals (cu t and uncu t) of C. ch inensis in ou r p lo t is 288. If w e reduce
ou r study area to the size of the p revious study area (1200 m 2) , the density of all individuals is seven individuals ö100 m 2, and
fou r individuals ö100 m 2 w ith heigh ts betw een 0. 5 m and 1. 5 m. T h is is considerab ly few er than found in the p revious study.
A lthough no C. ch inensis seedlings w ere found in the p revious study [12 ] , the study area w as sm all (fou r 1 m × 1 m
subp lo ts w ith in the 1200 m 2 area). W e found on ly 12 seedlings (L ife Stage I) in ou r p lo t, and they w ere concen trated in the
192312 期 王峥峰　等: 人为干扰下南亚热带厚壳桂种群分布格局 　
low er2slope of the p lo t, w ithou t any po sit ive associat ion w ith o ther life stages (F ig. 1). A s in o ther fo rests[15 ], the seedling
bank is impo rtan t fo r fo rest regenerat ion [16 ]. In the fu tu re, the fract ion of seedlings that en ter the sap ling stage is unknow n.
Given the iso lat ion of th is fo rest and hum an activit ies w ith in it, w e suspect that the seedling bank w ill disappear w ith in few
years.
F ig. 2　R ip ley’s L 2function analysis of the spatial pattern of C ryp tocary a ch inensis
T h ird, fo r iso lated trees, their seedlings shou ld be concen trated either around o r aw ay their paren t trees depending on the
level of seed p redation, as suggested by a species (C ryp tocary a a lba) in the sam e genus[17 ]. In ou r p revious study w e found that
C. ch inensis seedlings w ere clumped bu t independen tly associated w ith adu lt t rees in a low hum an distu rbance fo rest,
suggest ing that a su itab le m icrohab ita t w as requ ired fo r seedling estab lishm en t[6 ]. How ever, th is is no t the case fo r p resen t
study. Seedlings w ere random ly distribu t ion in sm all patches ( F ig. 1, F ig. 2a ) , indicat ing restricted regenerat ion, bu t
confirm ing that a su itab le m icrohab ita t is requ ired fo r seedling estab lishm en t[6 ]. In fo rests w ith low hum an impacts, seedlings
estab lish better in m icrohab ita ts w ith a lit ter layer andöo r on soft so il, bo th of w h ich have been severely distu rbed by ch ickens
in ou r study area. How ever, in tensive logging in ou r study area increases canopy gap s, w h ich shou ld be advan tageous fo r
2923　 生　态　学　报 25 卷
seedling su rvival[6 ]. T he low regenerat ion w e observed and its random distribu t ion m ay also be caused by low seed p roduction
by the few adu lt t rees o r by inb reeding dep ression of seeds o r seedlings in th is sm all popu lat ion [18—20 ]. O verall, ou r resu lts
indicate that hum an2induced spatia l pat tern s of C. ch inensis in ou r study area differ considerab ly from that in mo re natu ral
fo rests. In sites w ith low hum an distu rbance, C. ch inensis life stages w ere clu stered, w hereas w e found a near random
distribu t ion of trees, and regenerat ion is declin ing. Even if resto rat ion of th is fo rest is successfu l, its flo rist ic compo sit ion w ill
p robab ly never be iden tical to the p revious fo rest.
W e do no t know w hat compensat ion w ill be requ ired to convince local peop le to p ro tect th is fo rest. M o re impo rtan t ly,
law s and po licies govern ing natu ral resou rces are st ill no t sufficien t to tack le the scale of the conservat ion p rob lem s. T he
governm en t shou ld design a mo re effect ive conservat ion stra tegy invo lving local peop le to p ro tect and m anage fo rest
b iodiversity. In addit ion, fu rther research in to the popu lat ion genetics, dispersal, po llinat ion, seed bank, regenerat ion, and
hab ita t requ irem en ts of C. ch inensis w ill be needed to fu lly understand the spat ia l distribu t ion of th is species, and the p ro tect ion
of the fo rest.
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