Milcu Alexandru, Partsch Stephan, Scherber Christoph, Weisser Wolfgang W, Scheu Stefan
NERC Centre for Population Biology, Division of Biology, Imperial College, Silwood Park, Ascot SL5 7PY, United Kingdom.
Ecology. 2008 Jul;89(7):1872-82. doi: 10.1890/07-1377.1.
The role of species and functional group diversity of primary producers for decomposers and decomposition processes is little understood. We made use of the "Jena Biodiversity Experiment" and tested the hypothesis that increasing plant species (1, 4, and 16 species) and functional group diversity (1, 2, 3, and 4 groups) beneficially affects decomposer density and activity and therefore the decomposition of plant litter material. Furthermore, by manipulating the densities of decomposers (earthworms and springtails) within the plant diversity gradient we investigated how the interactions between plant diversity and decomposer densities affect the decomposition of litter belonging to different plant functional groups (grasses, herbs, and legumes). Positive effects of increasing plant species or functional group diversity on earthworms (biomass and density) and microbial biomass were mainly due to the increased incidence of legumes with increasing diversity. Neither plant species diversity nor functional group diversity affected litter decomposition, However, litter decomposition varied with decomposer and plant functional group identity (of both living plants and plant litter). While springtail removal generally had little effect on decomposition, increased earthworm density accelerated the decomposition of nitrogen-rich legume litter, and this was more pronounced at higher plant diversity. The results suggest that earthworms (Lumbricus terrestris L.) and legumes function as keystone organisms for grassland decomposition processes and presumably contribute to the recorded increase in primary productivity with increasing plant diversity.
初级生产者的物种和功能群多样性对分解者及分解过程的作用鲜为人知。我们利用了“耶拿生物多样性实验”，并检验了以下假设：增加植物物种（1种、4种和16种）和功能群多样性（1组、2组、3组和4组）会对分解者密度和活性产生有益影响，进而影响植物凋落物的分解。此外，通过在植物多样性梯度内操纵分解者（蚯蚓和跳虫）的密度，我们研究了植物多样性与分解者密度之间的相互作用如何影响属于不同植物功能群（禾本科、草本植物和豆科植物）的凋落物的分解。植物物种或功能群多样性增加对蚯蚓（生物量和密度）和微生物生物量的积极影响主要归因于随着多样性增加豆科植物出现频率的增加。植物物种多样性和功能群多样性均未影响凋落物分解，然而，凋落物分解随分解者和植物功能群特性（包括活植物和植物凋落物）而变化。虽然去除跳虫通常对分解影响不大，但增加蚯蚓密度加速了富含氮的豆科植物凋落物的分解，且在较高植物多样性水平下这种情况更明显。结果表明，蚯蚓（Lumbricus terrestris L.）和豆科植物作为草原分解过程的关键生物发挥作用，并且可能促成了随着植物多样性增加而记录到的初级生产力的提高。
