全 文 ：第 t 9卷第 2期
l 999年 3月
生 态 学 报
ACTA ECOl OGICA SINIC
Vol 】9．NO 2
M ar ，t 999
南亚热带常绿阔叶林粘木种群
／ 2／ 营养元素的分布与循环
宋 君 王伯荪 彭少麟 V
7I 3，
黄铭洪
； 州 j1。275) (中国科学 鬲 ’’ 5】o07。) (香港懂会大学 香港 九龙塘)
摘要 从种群角度研究了国家级保护植物牯木不同器官和土壤中氮、辟、钾 钙、锌 5种元素的分布和循环 ．
研 究结果 表 明 ：
(1)土壤中的 N和肓机质古量丰富，磷的贮量啦I较大于多 粤带林 ．c N 比率接近 10．显示着森林址于
稳定状态。
(2)营 养元素在不同成熟阶段的叶中是不l司的：蚰叶杠较成熟叫具较高的 N、P、K，而成熟叶和老ot则吉
较高的 ca和 Mg
(3)不 同成熟阶段的叶中，N：P比具有重要意义，N P比对于反映 P的供应是一个很好的指 标
(4)七壤中营养元索随着森林中营养元素的良好供应而发生转移 ，N、P K转移卒分别为 15 5％，75 5
和 53 0 ，而 P的再循环是与 N密切相关 ．根据 Vitousek假 |兑．P则是处于紧密循环状态
(5)边材和心材中的 P、Mg、Ca、N和 K的音量无显著差异，但树皮中的营养元索古量则高于术材，
(6)叶子中 N、P、K含量最高，而忖皮中则以 和 Mg含量最高 。
(7)粘木种群的营养元素 、P K、Ca Mg)贮量为 579 Okg／hm -占整十乔木树种贮量的 18％
(8)N、P、K、Ca Mg的周转时间分别为 12 1，l3 9，18 8，12．2和 1 9．04a，较干旱热带林的营养元素的循
环为低
Y
关键词 笆兰塑 ，宣羞垂 ，±l泣 埋
^
THE SToRAGE AND CYCLING NUTRIENT 0F Ixonanthes
chinensis IN S0UTH SUBTRoPIC BRoAD—LEAF
EVERGREEN FoRESTS，HEISHIDING NATURAL
RESERVE，GUANGDoNG PRoVINCE
S0NG Jun W ANG Bo—Sun PENG Shao—I in
‘zh雠 gs Univ~sity．Guangzhou，510275．China) (S~th ChinaInstituge ofBotany．Guangxhou 510650，China)
W ONG M ing—Hong
(H ongKong Baptist，tlongKong， 。Ⅱ D曲 Tong．Uhiaa)
Abstract Studied nutrient distribution．nutrient storage，and annum nutrients uptake in
different parts of trees and concluded that nutrients vary in leaves of different mature state
and in bark and wood．Internal cycling of N tP，K indicates the conservation recycling of
* Th project supported by the National Foundation of Science(No．39270144)
Received July l8，1996 Revised Dec．10，i 998
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224 生 态 学 报 19卷
these nutrients．Large amount of nutrients stored in this population indicate which play an
important role in the forest．The turnover time of N ．P．K ．Ca，M g in the population is
12．1，1 3．1，18．8．12．2 and 19．04 year respectively．
Key words broad—leaf evergreen forests．nutrient．storage and cycling．
1 INTRODUCTION
Heishiding Natural Reserve is located about 23 27 N and 111 o53’in Fengkai County in the~,-est part of
Guangdong Province．China．The Tropical Cancer is Jugt across the area．The total 8re8 of the reserve is
about 4000hm。．The parent material of most part of the Reserve is made up of granite．The elevation is 80
～ 930m ．with most of the area【neared at the elevation of 150～ 700m The main sol1 type Is red soIt．the hu
Flfus layer is quite thick．The climate of the region belong to south—subtropical wet monsoon climate tthe an—
nua1 mean temperature is 1 9．6 C ．the annua【rainfa[1 is 1 7．I4mm，the annual mean relative humidity is more
than 80 [ ．
The reserve area is covered with a wetl—developed forest vegetation．the study site was located in Du—
tian，Heishiding Natural Reserve．where served as a representative of the south subtropical lower montane
evergreen broad—leaved forest．A permanent ptot of 1700m in the forest was established in 1985．The forest
community is named as lxonanthes chinensis+Artocarpus styracifohus+Cryptrn：arya concinna association．
Ixonamhes chinensis is an evergreen tree which belongs to Ixonanthaceae．The family only has 8
species in the world and there are on[y 2 species distributing in China He&hiding is Just the northern limit
。f 1．chinensis which is also the national-class protected species．The mean density of 1．cfiinensis in the per—
manent plot is 184 individuals／hm ．the mean basal area is 96．6m ／hm ．and the distribution pattern is
clumps．Detailed information can be found in W ang and Liu[ ．
Althot。gh a lot of work on nutrient cycling has been done since the 60s．1imited data are now available
in tropical and subtropical forests，especially the work focuses on internal cycling，nutrient distribution
within species and at different part of the tree．In this studyta dominant species—— lxonanthes f^
was selected．the standing crop and flux of the five element(NtPtK。Ca and M g)within the population was
studied ．
2 M El"ItODS
2．1 Sampling of soil and ptant materials
2 1．1 SO l【
There was a very thin[ayer of litter on the soil surface，soil samples were coltected in two layers (0～
lOcm and1O～ 30cm )，soiltutor were dark brown and brown yetlow respectively，three replicates were col
leeted randomly under1．cfiinensisinthe studying plot on1 4 Januaryt1993(dry season)．Soil samples~-ere
collected and were air-dired in the laboratory，detritus and fine roots in the samples were carefutly removed
and sieved through a 2ram mesh for the following properties analysis．
2．1．2 Plant materials
Subsamples were taken from the four big standard trees(sampled in April 1993)。as described in the
biomass section[ ．Discs were separated quartly，two of them ~-eTe further separated into bark，sapwood
and heartwood．Three large branch samples about l～ 1．5m long were cut from up．middle and down layer
ofthe cTown．Branches neartrunk，and atthemiddle of each branch were separatedinto bark，core ortom
posite (bark+ core) Leaves and teaf—bearing twigs~&-ere a[so separated from branch，while leaves of differ
ent mature state (young—light green；mature—dark green；otd—yellow)were sorted，roots w町 e sampled in
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2期 宋 君等：南亚热带常绿阔叶林枯木种群营养元素的分布与循环 225
the same way like branches，and different sizes of roots were separated into bark and core and mixed
according to each part．All these materials were oven dried at 60 C for 48 h．except for leaves which were
dried at 105 C for lh and then at 60 C for 48h．Discs from bole，branch and root were saw into manageable
pieces and then ground to power
2．2 Chemical analysis
2．2．1 Nutrients in soil
Total N was determined by Kjeldhal method．total P was analyzed by molybdenum—blue method．total
K by flame photometry Available P was extracted by hydrochlork acid and sulfuric acid and then analyzed
by molybdenum—blue method[ ．Available N was also determined by indophenol blue method
． Exchange～
able Ca t M g were leached by 1 M anlmoniumacetate solution and then analyzed by AASl_]．Bulk density
(0．655g／em )was measured．
2．2．2 N utrients in tree components
Tree parts collected were dried at 60 C for 48h and ground to powder for the analysis of nutrients in—
eluding N，P，K，Ca and M g．
About 0-5～ 1g litter samples (three replicates for each sample) were digested in concentrated
(HNO3)：concentrated (H zSO·)：60 (HCIO 4)一 8：1：1(V／V)ant．analyzed by Hitachi 180—80 Polarized
Zeeman Atomic Absorption Spectrophotometer for K，Ca and Mg concentration - ．
About 0-5～ lg samples were digested hy sulfuric acid with several drops of(60g)HC10 ，the digest—
ed solution was used to determine N by an auto—analyzer(Lachat Quick—Chemical Analyzer)，while P
was determined cDl0rlmeterical】y by molybdenum—blue method using a 721一spectr0ph0t0meter ．
2．3 Caleulatlon
All the data were presented as nlean±SD．The amount of nutrients in soil(0～ 30cm)was dete mi d
from bulk density，soil volume and nutrient values．
Standing crop of nutrients for vegetation components were computed by multiplying dry weights of
each component by their mean nutrient concentrations．The standing contents of nutrients in different com—
ponents were combined to obtain total nutrient storage in the vegetation．The nutrient uptake by trunk and
branches was computed by multiplying the annual biomass increment of different components by their re—
spective nutrient concentration in wood part on the assumption that the bark did not change in a year perl—
od．The yearly nutrient uptake by leaves was assumed as nutrient contents in leaf iTl~ts$plus nutrient con
tent m ass lncrem ent．
Internal cycling or nutrient retranslocation was estimated by using nutrient
．
／Ca ratios，assuming that
Ca is immobile once it reaches[eaves．If(nutrient concentration in green leaf)／(Ca in green leaf)一oT，and
(nutrient concentration in leaf litter)／(Ca in leaflitter)一 tthen“ retranslocation一 ( —Y)／T 1 00 ．In
this study，the old [eaves(nearly falen)were used to estimate the rerm slocat10n 0f N，P，K and M Ⅱin
1．chinensis．
3 RIgSULTS
3．1 The properties of the soil under 1．Chinensis trees in the study site
Nutrient concentrations of different layers were presented in table 1．
Total nutrient concentrations were higher in the top(0～ 10era)than in the layer about(1O～ 30cm )
for contents of organic matter，total N，total P and available N and P contents were 300X10 and 12，5×
10一 fortop soil and151×10 and1 0-8×10 (V／V)forthelayer(1O~30cm)．ExchangeableCa．Mg and
K contents were 0．02 ，0．002 and 0．021 for top soil and 0．023 ，0．024 and 0．014 for the layer
(1 O～ 30cm )，the difference between the two layer was smal1．C ：N ratios for the two layers were 12．5 and
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