Understory vegetation, dominated by dwarf bamboo (Sasa spp.) in Japan, has been damaged by an overabundance of deer. Declining Sasa density may induce a decrease in litter decomposition due to the changes in soil environments. The effect of the environmental changes may also differ among litter from differenttree species. The objective of this study was to examine effects of declining Sasa density on litter decomposition in a cool-temperate mixed forest, with a focus on the effects of environmental factors and soil mesofauna on different litter species. The decomposition of three litter species was evaluated using litter bags with two different mesh sizes to consider different litter decomposability and control the accessibility of soil mesofauna. With decreasing Sasa density, soil water content increased whereas the number of soil mesofauna decreased. Litter mass loss decreased with declining Sasa density. Soil water content was negatively correlated with litter mass loss in the smaller mesh. Additionally, negative effects of Sasa degradation on litter decomposition did not change with litter species, but these effects changed among mesh sizes, suggesting that the effects of the decomposer community on litter decomposition changed with environmental conditions induced bySasadegradation. Complex interaction between decomposer communities and local environmental factors should be studied in further studies with longer periods over a wide range of areas.

在日本，矮矮竹（Sasa spp。）占主导地位的林下植被已被鹿的过量破坏。由于土壤环境的变化，Sasa密度下降可能会导致凋落物分解的减少。不同树种的凋落物之间环境变化的影响也可能不同。这项研究的目的是研究降低Sasa的影响密度对冷温混交林凋落物分解的影响，重点是环境因素和土壤中生动物对不同凋落物物种的影响。使用具有两种不同网眼尺寸的垃圾袋评估了三种垃圾的分解，以考虑不同的垃圾分解性并控制土壤中生动物的可及性。随着Sasa密度的降低，土壤含水量增加，而中型动物的数量减少。随Sasa密度下降，凋落物质量损失减少。在较小的网格中，土壤含水量与凋落物质量损失呈负相关。此外，Sasa的负面影响凋落物分解对凋落物分解的影响并没有随着凋落物种类的变化而改变，但是这些影响在网眼尺寸之间变化，这表明分解物群落对凋落物分解的影响会随着Sasa降解引起的环境条件而改变。分解器群落与当地环境因素之间复杂的相互作用应在更广泛的区域内进行更长时间的进一步研究。