Background and aims

The degradation of Moso bamboo (Phyllostachys edulis) forests was reported to dominate soil organic carbon (SOC) accumulation via primarily increased litterfall and root secretions. However, to what extent degradation affects SOC fractions and the mechanisms underlying different degraded durations for SOC stability remain uncertain.

Methods

The vegetation spatial structure, basic soil physiochemical properties, SOC and its components, and microbial traits in four degradation categories of Moso bamboo forests were analyzed. Multiple statistical analyses were further conducted to explore the underlying mechanisms controlling the changing SOC pool size and stability under degradation.

Results

Significantly higher SOC pools (5.40% to 33.62%) and POC/SOC ratios (11.26% to 30.68%), lower MAOC/SOC ratios (5.93% to 18.28%), and thus SOC stability, were reduced by degradation. Degraded Moso bamboo forests had higher age mingling (18.17%), more aggregated distribution (35.76%), and more intense competition (48.87%). This impacted increases in C inputs into soil from aboveground plants and, therefore, increased SOC and POC contents in the topsoil. Moreover, degradation reduced bacterial diversity and shifted the community from K- to r-strategists; fungal diversity remained unaffected, and saprotrophic fungi (r-) dominated the fungal community composition in soil. Consequently, microorganisms were highly involved in the shift from MAOC to POC, with implications for bacterial community diversity, life-history strategy, and increasing saprotrophic fungi. These alterations led to increased SOC storage but decreased its stability.

Conclusions

Overall, degradation-induced changes in plants, microbial communities, SOC fractions, and SOC stability are key processes for understanding plant-soil interactions under global change.

中文翻译：

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微生物特征对退化毛竹林土壤有机碳稳定性的影响

 背景和目标

据报道，毛竹（ Phyllostachys edulis ）森林的退化主要通过增加凋落物和根分泌物来主导土壤有机碳（SOC）的积累。然而，退化在多大程度上影响 SOC 分数以及不同退化持续时间对 SOC 稳定性的潜在机制仍不确定。

 方法

分析了毛竹林4个退化类别的植被空间结构、土壤基本理化性质、SOC及其组成、微生物特征。进一步进行了多项统计分析，以探索控制 SOC 池大小变化和退化下稳定性的潜在机制。

 结果

SOC 池（5.40% 至 33.62%）和 POC/SOC 比率（11.26% 至 30.68%）显着升高，MAOC/SOC 比率（5.93% 至 18.28%）较低，因此 SOC 稳定性因退化而降低。退化毛竹林年龄混杂度较高（18.17%），聚集分布较多（35.76%），竞争更加激烈（48.87%）。这影响了地上植物向土壤输入的碳的增加，因此增加了表土中 SOC 和 POC 的含量。此外，降解降低了细菌多样性，并将群落从 K-策略转变为 r-策略；真菌多样性未受影响，腐生真菌（r-）在土壤中的真菌群落组成中占主导地位。因此，微生物高度参与从 MAOC 到 POC 的转变，这对细菌群落多样性、生活史策略和腐生真菌的增加具有影响。这些改变导致 SOC 存储增加，但降低了其稳定性。

 结论

总体而言，退化引起的植物、微生物群落、SOC 分数和 SOC 稳定性的变化是了解全球变化下植物-土壤相互作用的关键过程。