Abstract Despite recent improvements in understanding the composition of microbial communities in forest soils, fundamental questions regarding how their dynamics and function vary with forest management strategies, such as stand density, and the factors that affect them are still unclear. In this study, the spectrophotometry and high-throughput sequencing technology were used to determine enzyme activities and microbial community composition in the topsoil (0–20 cm) of 35-year-old Chinese fir plantations with five stand densities. The results showed that stand density had significant effects on soil fungal community composition and diversity and the activity of catalase and sucrase. However, stand density had no significant effects on the bacterial communities, although the diversity of the bacterial communities varied with stand density. Overall, the increase in stand density reduced the activities of catalase, urease and surase and the Chao1 and Shannon diversity of bacterial and fungal communities. We found that positive correlations between enzyme activities and microbial diversity indices were significant. We also found that bacterial community compositions were significantly influenced by pH, alkali available N, available P and available K, and that fungal community composition was significantly influenced by pH, soil moisture, total N, alkali available N, available P and available K. Our results provide important insights into the effect of stand density on soil enzyme activities and microbial community composition, which is certainly significant for developing stand density regulation strategies to mitigate the effects of degradation of soil biological activities.

中文翻译：

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林分密度对亚热带杉木 (Lamb.) Hook 人工林土壤微生物群落组成和酶活性的影响

摘要 尽管最近对森林土壤中微生物群落组成的理解有所改进，但关于它们的动态和功能如何随森林管理策略（例如林分密度）以及影响它们的因素而变化的基本问题仍不清楚。本研究采用分光光度法和高通量测序技术，测定了 5 个林分密度的 35 年树龄杉木人工林表土（0-20 cm）的酶活性和微生物群落组成。结果表明，林分密度对土壤真菌群落组成和多样性以及过氧化氢酶和蔗糖酶的活性有显着影响。然而，林分密度对细菌群落没有显着影响，尽管细菌群落的多样性随林分密度而变化。全面的，林分密度的增加降低了过氧化氢酶、脲酶和苏氨酸酶的活性以及细菌和真菌群落的 Chao1 和 Shannon 多样性。我们发现酶活性与微生物多样性指数之间呈显着正相关。我们还发现细菌群落组成受 pH、碱有效 N、有效 P 和有效 K 显着影响，真菌群落组成受 pH、土壤水分、全 N、碱有效 N、有效 P 和有效 K 显着影响。我们的研究结果为林分密度对土壤酶活性和微生物群落组成的影响提供了重要的见解，这对于制定林分密度调节策略以减轻土壤生物活性退化的影响无疑具有重要意义。