土壌動物と落葉特性の相互作用が分解動態を制御することを解明 (Interactions Between Soil Fauna and Litter Traits Drive Decomposition Dynamics)

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2026-05-15 中国科学院(CAS)

中国科学院西双版納熱帯植物園(XTBG)の研究チームは、土壌動物と落葉特性の相互作用が分解過程に大きく影響することを明らかにした。研究成果は『Soil Biology and Biochemistry』に掲載された。研究では、中国南西部の熱帯雨林で1年間にわたり972個のリターバッグ実験を実施し、メッシュサイズを変えることで微生物のみ、メソファウナ、中・大型土壌動物(ヤスデ、ワラジムシ、ミミズなど)の影響を比較した。結果として、大型土壌動物は混合落葉の分解速度を大幅に促進し、樹木種間の混合効果も強化した一方、窒素含有量など初期落葉特性による分解予測能力を弱めることが判明した。微生物や小型動物のみの場合は落葉特性が分解速度をよく説明したが、大型土壌動物が加わるとその関係は消失した。研究は、生物多様性損失や気候変動下の生態系応答予測には、土壌動物の種類やサイズ構造を分解モデルへ組み込む必要性を示している。

土壌動物と落葉特性の相互作用が分解動態を制御することを解明 (Interactions Between Soil Fauna and Litter Traits Drive Decomposition Dynamics)
Field experiment testing how different groups of soil fauna interact with litter functional traits to influence mixed-litter decomposition. (Image by Gbadamassi G.O. Dossa)

<関連情報>

つる植物と樹木由来の落葉混合物の分解に対する落葉多様性、機能特性、および大型動物相の相互作用効果 Interactive effects of litter diversity, functional traits, and macrofauna on decomposition of litter mixtures from lianas and trees

Denis Mburu Njoroge, Yanlin Zhu, Jean Evans Israel Codjia, Juan Zuo, Gbadamassi G.O. Dossa, Yali Song, Douglas Schaefer, Mareike Roeder, Rhett D. Harrison, Johannes H.C. Cornelissen
Soil Biology and Biochemistry  Available online: 17 April 2026
DOI:https://doi.org/10.1016/j.soilbio.2026.110163

Highlights

  • Understanding decomposition drivers is vital for global C and nutrient cycles
  • Soil fauna size affects their ability to decompose leaf litter
  • Litter traits predict mixture decomposition only in the absence of macrofauna
  • Initial litter traits do not predict the litter mixing effect
  • Macrofauna accelerate decomposition and increase litter mixing effect in tree mixtures

Abstract

Understanding the effect of litter mixing on litter decomposition rates is a prerequisite for predicting global carbon and nutrient cycling. However, the complex interactions associated with the decomposition of litter mixtures hinder their inclusion in global models. Soil fauna play an important role in the decomposition of litter mixtures, and their body size affects their ability to decompose litter. However, how different groups of soil fauna interact with litter traits to drive litter mixture decomposition remains poorly known. Here, through a field leaf litterbag decomposition experiment, we tested how soil fauna size and litter traits affect the decomposition of litter mixtures. We hypothesized that: (H1) The rate of decomposition and the magnitude of the litter mixing effect are greater in the presence of macrofauna. (H2) The effect of litter traits on the litter decomposition rate and the litter mixing effect decreases as the size of soil fauna increases. We used litter from two plant functional groups (trees and lianas) and incubated 27 litter treatments, including 12 single species, six 2-species mixtures, and nine 4-species mixtures. Each litter treatment was incubated using three litterbag mesh size treatments representing access to fauna of increasing body size (0.07 mm, 2.0 mm, and 5.0 mm) for 365 days. Both H1 and H2 were only partially supported. Macrofauna access accelerated decomposition and increased the litter mixing effect for tree-only mixtures. Initial litter traits predicted mixture decomposition rates in the presence of microbes and mesofauna, but not in the presence of macrofauna. Surprisingly, initial traits did not predict the litter mixing effect. This study highlights that litter traits may vary in their importance to different groups of soil fauna. In nature, therefore, where fauna communities (micro-, meso-, and macro-fauna) co-occur, and litter mixtures vary spatially, it may be difficult to predict decomposition rates.

生物環境工学
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