亚热带森林转换对凋落叶分解过程中土壤无脊椎动物群落结构的影响

Effects of Subtropical Forest Conversion on Soil Invertebrate Community Structure during the Decomposition of Leaf Litter

以地带性植被建群种米槠(Castanopsis carlesii)的凋落叶为研究对象,采用不同孔径凋落物袋排除土壤无脊椎动物的方法,分析常绿阔叶林转换为米槠人工林后凋落叶分解过程中土壤无脊椎动物群落结构、多样性和功能群。以米槠凋落叶完全分解为研究期间,共捕获土壤无脊椎动物6417头,隶属3门12纲27目114科,其中白蚁科为优势类群。2种林分凋落叶分解过程中总的、大型土壤无脊椎动物丰度均于30 d到达峰值,而中小型为15 d,类群数均在91 d达到峰值,整体的动态变化规律较为相似。常绿阔叶林转换为人工林后,土壤无脊椎动物丰度和类群数显著降低,其中中小型土壤无脊椎动物丰度的响应更为迅速,降低了33.67%;林型转换后,土壤无脊椎动物各功能群个体数量均有所减少,其中杂食性土壤无脊椎动物对林型转换最为敏感,降幅达37.85%;土壤无脊椎动物群落的多样性指数、丰富度指数、优势度指数和均匀度指数也均有所降低。冗余分析表明,土壤有机碳含量和土壤温度是调控凋落叶分解过程中土壤无脊椎动物群落结构的主要因子,总解释率达22.4%。可见,亚热带常绿阔叶林转换为人工林的森林林型转换会导致森林地表理化特征变化,使得米槠凋落叶分解过程中土壤无脊椎动物的群落结构更为简化,进而可能影响土壤无脊椎动物对凋落叶分解的贡献,最终深刻作用于亚热带森林物质循环和能量流动。

Our research focused on the leaf litter of Castanopsis carlesii,a group species in zonal vegetation,and the litter bags with different mesh sizes were used to analyze the community structure,diversity,and functional groups of soil invertebrates during the decomposition of leaf litter after the conversion of evergreen broadleaf forests into Castanopsis carlesii plantations.Throughout the complete decomposition period of Castanopsis carlesii leaf litter,a total of 6417 soil invertebrates from 3 phyla,12 classes,27 orders,and 114 families were captured,among which termites were the dominant group.During the decomposition of leaf litter,the abundance of total and macro soil invertebrates peaked at 30 days in both stands,while meso-micro soil invertebrates peaked at 15 days.The number of taxa reached its peak at 91 days.The overall dynamics of the two forest stands were relatively similar.After the forest conversion,the abundance and group numbers of soil invertebrates during the leaf litter decomposition decreased significantly,with meso-micro invertebrates responding more rapidly,decreasing by 33.67%;the number of individuals in each functional group of soil invertebrates declined swiftly after the conversion,with the omnivorous soil invertebrates being the most sensitive to the conversion,with a decrease of 37.85%;it also reduced the diversity index,richness index,dominance index,and the evenness index of soil invertebrate communities during the decomposition of leaf litter.Redundancy analysis demonstrated that soil organic carbon content and soil temperature were the main factors affecting the community structure of soil invertebrates,explaining 22.4%of the variance during the decomposition.Hence,it is evident that the conversion of subtropical evergreen broad-leaved forests into plantations changed the physicochemical characteristics of the surface.This simplification in the community structure of soil invertebrates during the decomposition of leaf litter may,in turn,affect the contribution of these invertebrates to leaf litter decomposition,ultimately impacting material cycling and energy flow in subtropical forests significantly.