南亚热带常绿阔叶林植物不同分类水平上的空间分布格局及空间关联

Spatial Distribution Patterns and Spatial Associations of Evergreen Broad-leaved Forest Plants in Tropical South Asia at Different Taxonomic Levels

为探讨中国南亚热带常绿阔叶林植物在科、属、种不同分类水平上空间分布格局、空间关联的共性规律及其成因,加深对中国南亚热带区域群落生态学特性的了解。选取中国南亚热带区域4个不同纬度样地中个体数量排名前3的优势科为研究对象(DBH,diameter at breast height≥1 cm),采用L(t)方程统计科、属、种空间分布格局,并以空间聚集程度指标L10比较各样地科、属、种水平的聚集程度,采用L12(t)方程分析各样地科、属、种间个体的空间关联。结果表明,(1)聚集分布是南亚热带常绿阔叶林群落植物在科、属、种3个分类水平上的最主要空间分布格局类型;各样地在不同分类水平上的聚集分布比例随纬度梯度变化未表现出明显规律,但均表现出分布格局的尺度依赖性,即随着空间尺度增大,聚集分布比例下降,随机分布比例上升这一共性规律。(2)各样地空间聚集程度L10均表现出随科→属→种分类水平细化而增大的规律。(3)独立不相关为各样地不同分类水平空间关联的最主要类型;独立不相关所占比例在科、属、种3个水平的变化规律不一致,但在物种水平,各样地3类亲缘远近的独立不相关占各类种间关联比例表现出同科同属占比>不同科不同属占比>同科不同属占比这一共性规律。(4)亲缘个体在种、属水平表现出独立不相关占比随纬度从高到低逐渐减小的趋势,而在科水平统计数据未能体现此规律。综上,植物分类水平的细化一定程度上可以加强空间聚集程度,亲缘关系越近的个体越趋向于聚集分布;不同分类水平上亲缘个体的空间分布格局及关联性,可以真实地反映不同亲缘关系远近群体对生境的适应性及资源利用特点,亲缘关系是影响群落中物种共存和分布的重要因素。

This study investigated the common patterns and causes of spatial distribution and association of evergreen broad-leaved forest plants at different taxonomic levels from families to species in the south subtropics of China and expands our understanding of the ecological characteristics of regional communities in the south subtropics of China.In this study,the top three dominant families(DBH,Diameter at breast height≥1 cm)in the number of individuals in four different latitudinal sample sites in the south subtropical region of China were selected.We used the L(t)function to count the spatial distribution patterns of families,genera and species,and compared the degree of aggregation at the level of families,genera and species in each plot with the spatial aggregation index L10,and used the L12(t)function to analyze the spatial association of individuals among families,genera,and species in each plot.The results showed that(1)aggregation distribution was the most important spatial distribution pattern of plants in the southern subtropical broadleaf evergreen forest communities at three taxonomic levels.The proportion of aggregation distribution at each taxonomic level did not show a clear pattern with latitudinal gradient,but all showed a scale-dependent distribution pattern(i.e.,the proportion of aggregation distribution decreased and the proportion of random distribution increased as the spatial scale increased.)(2)The spatial aggregation degree L10 of each sample site increased with the refinement of family→genera→species taxonomic levels.(3)mutual independence was the most dominant type of spatial association at different taxonomic levels at each site.Although the proportion of this type of association varied among the three levels of family,genus and species,it followed the same order(i.e.,same family to same genus>different family to different genus>same family to different genus)at the species level at each site.(4)The proportion of independently unrelated individuals at the species and genus levels tended to decrease from higher to lower latitudes,while the statistics at the family level failed to reflect this pattern.In summary,the refinement of plant taxonomic levels can strengthen the degree of spatial aggregation to a certain extent,and individuals with closer affinities tend to be more aggregated and distributed;the spatial distribution patterns and correlations of related individuals at different taxonomic levels can truly reflect the habitat adaptation and resource utilization characteristics of groups with different affinities,and affinities are important factors that influence the coexistence and distribution of species in communities.