Aims

Invasive plants not only alter aboveground biodiversity but also belowground microbial community composition to facilitate their growth and competitiveness. However, how plant invasion affects soil microbial resource limitation and metabolic activity, and their linkages with litter and soil stoichiometries remain largely unknown.

Methods

We investigated the carbon (C): nitrogen (N): phosphorus (P) stoichiometries of litter, soil, microbe and extracellular enzymes, composition of main microbial groups and substrate utilization rate in a subtropical forest invaded by Moso bamboo (Phyllostachys edulis) and those in adjacent broadleaf and mixed bamboo-broadleaf forests.

Results

Bamboo invasion significantly decreased annual litter production, litter C: P and N: P ratios, and soil C:N and C:P ratios, whereas increased microbial biomass C:N and C:P ratios, resulting in decreased C:N and C:P imbalances between soil microorganisms and their resources. Bamboo invasion decreased the N and P acquiring enzymes activities, mitigated the status of microbial N and P limitation as indicated by enzymatic stoichiometry, and caused a higher C use efficiency. Soil microbial community structure was shifted towards a lower fungi: bacteria (F:B) ratio in bamboo forest. Bamboo forest soil showed a lower capacity of microbes to use N-rich resources in comparison to C-rich resources. Structural equation modeling suggested a direct and negative effect of C:N imbalance on microbial N limitation and metabolic capacity.

Conclusions

This study suggests the importance of stoichiometric imbalance between decomposers and their resources in regulating soil microbial community structure and enzyme activities following plant invasion.

中文翻译：

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毛竹入侵亚热带阔叶林凋落物和土壤C:N:P化学计量与土壤微生物资源限制和群落结构的联系

宗旨

入侵植物不仅会改变地上生物多样性，还会改变地下微生物群落组成，以促进它们的生长和竞争力。然而，植物入侵如何影响土壤微生物资源限制和代谢活动，以及它们与凋落物和土壤化学计量的联系在很大程度上仍然未知。

方法

我们研究了毛竹（Phyllostachys edulis）入侵的亚热带森林中凋落物、土壤、微生物和细胞外酶的碳（C）：氮（N）：磷（P）化学计量，主要微生物群的组成和底物利用率。邻近阔叶林和竹阔叶混交林。

结果

竹子入侵显着降低了年度凋落物产量、凋落物 C:P 和 N:P 比率以及土壤 C:N 和 C:P 比率，而微生物生物量 C:N 和 C:P 比率增加，导致 C:N 和 C :P 土壤微生物与其资源之间的不平衡。竹子入侵降低了 N 和 P 获取酶的活性，缓解了酶化学计量学表明的微生物 N 和 P 限制状态，并导致更高的 C 利用率。竹林土壤微生物群落结构向较低的真菌：细菌（F：B）比例转变。与富碳资源相比，竹林土壤中微生物利用富氮资源的能力较低。结构方程模型表明 C:N 失衡对微生物 N 限制和代谢能力有直接和负面的影响。

结论

这项研究表明分解者及其资源之间的化学计量失衡在植物入侵后调节土壤微生物群落结构和酶活性方面的重要性。