Anthropogenic disturbance affects wood decomposition directly and indirectly through microclimatic and biotic drivers

do Nascimento, R.O. and Berenguer, E. and Ferreira, J. and Stevens, C. and Filho, M.A.A. and Barlow, J. (2026) Anthropogenic disturbance affects wood decomposition directly and indirectly through microclimatic and biotic drivers. Forest Ecology and Management, 599: 123275. ISSN 0378-1127

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Abstract

Amazonian forests play a key role in the dynamics of global ecosystem services. Human-modified forests, which already cover more than one million km2 in the region, generate still uncertain threats to the carbon cycle, such as the influence on wood decomposition rates. Understanding the factors regulating deadwood decomposition is critical for improving carbon flux predictions in tropical forests. Using a one-year standardized field experiment in easter Amazon considering 15 native tree species, this study evaluated how forest disturbance, microclimate, wood traits and decomposers activity affect wood decomposition processes. Quarterly, wood decomposition increased gradually, reaching 0.21 ± 0.29 proportional mass loss after 12 months. Wood density played a crucial role confirming it as a fundamental predictor of decay rates, with lower density woods showing higher decomposition rates. Despite the absence of significant differences in decomposition rates among forest disturbance classes, structural equation models revealed significant indirect pathways, where anthropogenic canopy openness altered microclimatic conditions which in turn suppressed decomposer activity, such as termites, a key biotic driver of decomposition. Our findings provide novel experimental evidence that forest structure and microclimate mediate the role of decomposers in carbon cycling, emphasizing the need to incorporate functional wood traits and indirect disturbance effects into carbon models to better predict ecosystem responses under increasing forest degradation and climate change.