不同尺度上环境因子对常绿阔叶林群落的谱系结构的影响

doi:10.3773/j.issn.1005-264x.2010.03.008

摘要/Abstract

摘要：

群落的谱系结构是反映作用于群落组成的各种生态过程的综合指标。通过研究群落的谱系结构, 能够有效地推断形成群落谱系结构的生态过程。该文从环境因子(海拔、地形、pH、土壤湿度和土壤元素等)对群落谱系结构的影响这一视角出发, 采用圆形随机取样, 在半径为5、25、50、75和100 m 5个尺度上, 深入研究了古田山24 hm²永久样地群落的谱系结构。研究发现: 古田山样地在所有研究尺度上(半径 > 5 m)都表现为谱系聚集, 随着尺度的增加, 群落的聚集程度呈现出先增加后下降的格局。采用多元线性回归模型分析环境因子对群落谱系结构的影响时发现: 随着尺度的增加, 环境因子对群落谱系结构的影响逐渐增强; 在小尺度上, 环境因子对谱系结构没有显著影响, 这可能是由于小尺度上近缘种之间较强的竞争排斥作用所致。当尺度达到100 m半径时, 高海拔区域表现出谱系发散格局, 而低海拔区域保持谱系聚集, 这可能是由于古田山样地海拔较高的地带生境异质性较强和较大的干扰所致。该研究在所有的尺度上都表现出显著的谱系聚集, 与中性理论所预测的群落是物种的随机组合、无谱系结构相反, 因而为生态位理论提供了证据。

关键词: 环境因子, 大样地, 谱系结构, 空间尺度

Abstract:

Aims Phylogenetic structure of a community is a synthetical indicator reflecting underlying ecological processes. Understanding of the phylogenetic structure of a community will provide insights into the relative importance of different processes structuring the community. Our objectives are 1) examine the effects of environmental factors on phylogenetic structure; 2) test the prediction of neutral theory that the community is randomly assembled and the prediction of niche theory that the community is mainly determined by niche differentiation; and 3) determine the relative importance of neutral theory and niche theory in biodiversity maintenance in subtropical evergreen broadleaved forest.

Methods Gutianshan forest dynamic plot is located in the Gutianshan National Nature Reserve at Kaihua County, Zhejian Province of China. We randomly chose 1 000 subplots at five spatial scales of radii 5, 25, 50, 75 and 100 m in the Gutianshan forest dynamic plot and analyzed phylogenetic structure of subplots at these scales with net relatedness index (NRI). We analyzed the effect of environmental factors, including topographical factors, such as altitude, slope, aspect and convexity, and edaphic factors such as soil moisture, pH and 16 soil nutrients, on the community phylogenetic structure with multivariate regression.

Important findings Communities were phylogenetically clustered at all spatial scales, indicating that trees were more closely related to their neighbors than expected by chance. With increasing scale, the strength of clustering increased and then deceased. Multiple linear regression showed that environmental factors had almost no effect on phylogenetic structure at smaller scales, but strongly affected the community structure at larger scales (radius of 100 m). At the radius of 100 m, two types of different phylogenetic structure emerged: some of subplots kept clustering, yet others became overdispersed. The difference of phylogenetic community structures at scale of 100 m was mainly determined by altitude. Our results support the prediction of niche theory that the community phylogenetic structure is structured by niche differentiation, and do not support the prediction that the community phylogenetic structure is randomly assembled by ecological drift and dispersal limitation.

Key words: environmental factors, forest dynamics plot, phylogenetic structure, spatial scale

黄建雄, 郑凤英, 米湘成. 不同尺度上环境因子对常绿阔叶林群落的谱系结构的影响. 植物生态学报, 2010, 34(3): 309-315. DOI: 10.3773/j.issn.1005-264x.2010.03.008

HUANG Jian-Xiong, ZHENG Feng-Ying, MI Xiang-Cheng. Influence of environmental factors on phylogenetic structure at multiple spatial scales in an evergreen broad-leaved forest of China. Chinese Journal of Plant Ecology, 2010, 34(3): 309-315. DOI: 10.3773/j.issn.1005-264x.2010.03.008

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链接本文: https://www.plant-ecology.com/CN/10.3773/j.issn.1005-264x.2010.03.008

https://www.plant-ecology.com/CN/Y2010/V34/I3/309

图/表 6

图1 古田山森林样地地形图。古田山样地地形图表明东西向为600 m, 南北向为400 m, 曲面表示样地海拔高度从446.325 m (蓝色)到714.902 m (红色)。

Fig. 1 Topography of Gutianshan (GTS) forest dynamic plot. Topography of GTS forest dynamic plot indicates that the east-west axis of the plot is 600 m and the south-north axis of the plot is 400 m. The curved surface displays the altitude of the plot varies from 446.325 m (blue) to 714.902 m (red).

图2 在古田山森林样地5个尺度上1 000次随机抽样获得的净谱系亲缘关系指数(NRI)值的分布。

Fig. 2 Distribution of net relatedness index (NRI) values for 1 000 random samples at five scales in Gutianshan forest dynamic plot.

表1 5个尺度上净谱系亲缘关系指数(NRI)的分布概况及平均值大于0的一尾t检验

Table 1 Distributions of net relatedness index (NRI) values at five scales and one tail t-test of hypothesis that mean value of NRI is equal to zero

尺度 Scale (m)	平均值 Mean value of NRI	方差 Variance of NRI	t (df = 999)	p
5	0.3783599	0.9218890	12.4614	< 2.2e-16 ***
25	0.2316712	0.2107166	15.9596	< 2.2e-16 ***
50	0.4084871	0.1591331	32.3816	< 2.2e-16 ***
75	0.4100705	0.2843890	24.3166	< 2.2e-16 ***
100	0.2432730	0.5080883	10.7926	< 2.2e-16 ***

表2 不同尺度上环境因子对净谱系亲缘关系指数(NRI)的影响

Table 2 Effects of environmental factors on net relatedness index (NRI) at different scales

尺度(半径) Scale (radius)	5 m	25 m	50 m	75 m	100 m
R²	0.06413	0.19160	0.29400	0.49530	0.73880
极显著因子数 No. of environmental factors which affect NRI significantly	2	7	10	12	14

表3 海拔因子对净谱系亲缘关系指数(NRI)的单因子线性回归分析结果

Table 3 Effects of altitude on net relatedness index (NRI) by linear regression

尺度(半径) Scale (radius)	5 m	25 m	50 m	75 m	100 m
p	0.409	0.267	1.52e-05 ***	<2e-16 ***	<2e-16 ***
R²			0.01859	0.16710	0.34410

图3 100 m半径尺度上海拔与净谱系亲缘关系指数(NRI)的关系。随着海拔的增高NRI代表的群落谱系结构从发散转变为聚集。

Fig. 3 Net relatedness index (NRI) of samples against altitude at scale of radius of 100 m. The phylogenetic structure of communities turns from clustering to overdispersion with increasing altitude.

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