INRAE, UMR IAM, Université de Lorraine, Nancy, France.
Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, USA.
Mol Ecol. 2021 Apr;30(8):1921-1935. doi: 10.1111/mec.15828. Epub 2021 Mar 8.
Recent studies have highlighted that dead fungal mycelium represents an important fraction of soil carbon (C) and nitrogen (N) inputs and stocks. Consequently, identifying the microbial communities and the ecological factors that govern the decomposition of fungal necromass will provide critical insight into how fungal organic matter (OM) affects forest soil C and nutrient cycles. Here, we examined the microbial communities colonising fungal necromass during a multiyear decomposition experiment in a boreal forest, which included incubation bags with different mesh sizes to manipulate both plant root and microbial decomposer group access. Necromass-associated bacterial and fungal communities were taxonomically and functionally rich throughout the 30 months of incubation, with increasing abundances of oligotrophic bacteria and root-associated fungi (i.e., ectomycorrhizal, ericoid mycorrhizal and endophytic fungi) in the late stages of decomposition in the mesh bags to which they had access. Necromass-associated β-glucosidase activity was highest at 6 months, while leucine aminopeptidase peptidase was highest at 18 months. Based on an asymptotic decomposition model, root presence was associated with an initial faster rate of fungal necromass decomposition, but resulted in higher amounts of fungal necromass retained at later sampling times. Collectively, these results indicate that microbial community composition and enzyme activities on decomposing fungal necromass remain dynamic years after initial input, and that roots and their associated fungal symbionts result in the slowing of microbial necromass turnover with time.
最近的研究强调，死亡真菌菌丝体代表了土壤碳 (C) 和氮 (N) 输入和储量的一个重要部分。因此，确定控制真菌残体分解的微生物群落和生态因素将为了解真菌有机物质 (OM) 如何影响森林土壤 C 和养分循环提供重要的见解。在这里，我们在北方森林的一项多年分解实验中检查了定殖真菌残体的微生物群落，该实验包括具有不同网眼大小的培养袋，以操纵植物根系和微生物分解者群体的进入。在 30 个月的培养过程中，与真菌残体相关的细菌和真菌群落在分类学和功能上都非常丰富，在具有进入通道的网袋中，贫营养细菌和与根系相关的真菌（即外生菌根真菌、石楠菌根真菌和内生真菌）的丰度在分解的后期阶段增加。与真菌残体相关的β-葡萄糖苷酶活性在 6 个月时最高，而亮氨酸氨肽酶活性在 18 个月时最高。基于渐近分解模型，根的存在与真菌残体分解的初始更快速率相关，但导致在随后的采样时间保留更多的真菌残体。总的来说，这些结果表明，分解真菌残体的微生物群落组成和酶活性在初始输入多年后仍然具有动态性，并且根及其相关的真菌共生体随着时间的推移导致微生物残体周转率的减缓。
