Predicting changes in carbon and nutrient cycles in plantations requires a mechanistic understanding of the effects of stand age on soil quality and microbial communities. Here, we evaluated soil quality by using an integrated soil quality index (SQI) and traced the parallel shifts in fungal community composition using high‐throughput sequencing in a chronosequence of Chinese fir (Cunninghamia lanceolata) plantations (stand age of 3, 16, 25, 32, >80 years). Soil properties showed pronounced changes with stand age in the topsoil. Soil organic carbon (SOC), total nitrogen (TN) and available phosphorus (AP) were 2.1, 1.9 and 2.2 times higher, respectively, in the oldest stands than in the youngest stands. SQI of the top 5 cm increased logarithmically with stand age. Mycorrhizal fungi initially increased in younger stands, but then they were gradually replaced by saprotrophs in older stands due to larger litterfall. Strong positive correlations between saprotrophic fungi and key soil quality indicators, such as TN, AP and NH₄⁺, confirmed that abundance of decomposers is tightly linked with higher soil quality. Mycorrhizal orders Thelephorales, Sebacinales and Russulales increased in abundance and raised the activity of acid phosphatase to mobilise limiting phosphorus from organic matter. Consequently, mycorrhizal fungi are especially relevant in younger stands to acquire nutrients to sustain tree productivity. In developed stands, however, saprotrophic fungi are crucial in recycling nutrients from the litter. Collectively, the increase of topsoil quality during the life cycle of Chinese fir plantations is closely linked with the observed transition of fungal communities from mycorrhizae to saprotrophs.

中文翻译：

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杉木人工林时序真菌群落组成与土壤质量的紧密耦合

预测人工林中碳和养分循环的变化需要对林分年龄对土壤质量和微生物群落的影响进行机械理解。在这里，我们使用综合土壤质量指数（SQI）评估了土壤质量，并在杉木（Cunninghamia lanceolata）的时间序列中使用高通量测序追踪了真菌群落组成的平行变化。）人工林（年龄为3、16、25、32，> 80岁）。表层土壤的土壤性质随林龄的变化而显着变化。最老林分的土壤有机碳（SOC），总氮（TN）和有效磷（AP）分别是最年轻林分的2.1、1.9和2.2倍。最高5 cm的SQI与林分年龄成对数增长。菌根真菌最初在较年轻的林分中增加，但后来由于凋落物较大，在较年长的林分中逐渐被腐生菌所替代。腐生真菌与关键土壤质量指标（例如TN，AP和NH ₄ ^+）之间的强正相关关系，证明了分解剂的丰富与土壤质量的提高紧密相关。菌根订单革菌目，蜡壳耳目和红菇目中丰度增加，并且提出了酸性磷酸酶的活性，从有机物动员限制性磷。因此，菌根真菌在较年轻的林分中尤为重要，以获取养分以维持树木的生产力。然而，在发达的林分中，腐生真菌对于回收垫料中的养分至关重要。总的来说，杉木人工林生命周期中表土质量的提高与所观察到的真菌群落从菌根向腐生菌的转化密切相关。