Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
FEMS Microbiol Ecol. 2019 Jan 1;95(1). doi: 10.1093/femsec/fiy223.
Wood decomposition, a critical process in carbon and nutrient cycles, is influenced by environmental conditions, decomposer communities and substrate composition. While these factors differ between land and stream habitats, across-habitat comparisons of wood decay processes are rare, limiting our ability to evaluate the context- dependency of the drivers of decay. Here we tracked wood decomposition of three tree species placed in stream and terrestrial habitats in a lowland tropical forest in Panama. At 3 and 11 months we measured mass loss, wood nitrogen and wood polymer concentrations, and sampled wood-associated fungal and bacterial communities. After 11 months of decay we found that mass loss occurred 9% faster in streams than on land, but loss of cellulose, hemicellulose and lignin did not differ between habitats. We also observed large differences in microbial decomposer communities between habitats. Overall, we found faster mass loss of wood in water, but no differences in biotic decay processes between habitats despite distinct microbial communities in streams and on land. Our research challenges the assumption that wood decays relatively slowly in water reflecting unfavorable environmental conditions and a limited capacity of aquatic microbial communities to effectively degrade wood polymers.
木材分解是碳和养分循环中的一个关键过程，受到环境条件、分解者群落和基质组成的影响。虽然这些因素在陆地和溪流生境之间存在差异，但跨生境的木材分解过程比较少见，这限制了我们评估分解驱动因素的背景依赖性的能力。在这里，我们在巴拿马的一个低地热带森林中，将三种树种分别放置在溪流和陆地生境中，追踪其木材分解情况。在 3 个月和 11 个月时，我们测量了质量损失、木材氮和木材聚合物浓度，并对与木材相关的真菌和细菌群落进行了采样。在 11 个月的分解后，我们发现木材在溪流中的质量损失比在陆地上快 9%，但纤维素、半纤维素和木质素的损失在生境之间没有差异。我们还观察到生境之间微生物分解者群落存在很大差异。总的来说，我们发现木材在水中的质量损失更快，但尽管溪流和陆地的微生物群落明显不同，但生境之间的生物分解过程没有差异。我们的研究挑战了木材在水中相对缓慢分解反映不利环境条件和水生微生物群落有效降解木材聚合物能力有限的假设。
