Aims

Aboveground litter inputs have been modified by global changes in plantation forests, where understory management is also prevalent, which may alter soil fertility and stand productivity. This study aimed to quantify the specific roles of litter and understory in affecting soil carbon (C) and nitrogen (N) dynamics.

Methods

A field experiment was established with four treatments, namely, litter addition (LA), understory removal (UR), litter addition and understory removal (LA + UR), and a control, in a subtropical Cunninghamia lanceolata plantation. Topsoil δ¹³C, organic C concentration, storage and decomposition, mineral N, N mineralization, and C and N hydrolase activities were analyzed.

Results

Litter addition significantly increased soil organic C, macro-particulate organic C (macro-POC) and mineral N at a 0–5 cm depth, but decreased δ¹³C_macro-POC at 0–5 cm and 5–10 cm depths. Understory removal significantly increased soil NH₄⁺-N, the rates of nitrification and net N mineralization as well as the soil organic C respiration rate at the two depths, while it decreased the C storage in bulk soil, especially in mineral protected pools. The activities of β-glucosidase and β-N-acetylglucosaminidase increased with litter addition and understory removal, respectively.

Conclusions

Litter addition tends to improve soil C quantity and quality due to fresh organic C inputs, while understory removal helps increase the N supply via the acceleration of N mineralization and the absence of understory plant uptake.

中文翻译：

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亚热带人工林的凋落物添加和林下清除影响了土壤有机碳质量和矿质氮的供应

目的

人工林的全球变化已经改变了地上凋落物的输入，在林下管理也很普遍，这可能会改变土壤肥力和林分生产力。这项研究旨在量化凋落物和林下植被在影响土壤碳（C）和氮（N）动态方面的特定作用。

方法

在亚热带杉木杉木人工林中，采用四种处理方法建立了田间试验，即凋落物添加（LA），林下清除（UR），凋落物添加和林下清除（LA + UR）以及对照。表土δ ¹³ C，有机碳的浓度，储存和分解，矿物N，N-矿化，和C和N水解酶活性的分析。

结果

垫料此外显著增加了土壤的有机C，宏观颗粒有机C（宏观POC）和无机氮在0-5厘米的深度，但降低的δ ¹³ C ^_宏POC在0-5厘米和5-10厘米的深度。清除林下土壤能显着增加土壤NH ₄ ⁺ -N，硝化和净氮矿化速率以及两个深度的土壤有机碳呼吸速率，同时会降低散装土壤中的碳存储量，尤其是在矿物质保护池中。β-葡萄糖苷酶和β-N-乙酰氨基葡萄糖苷酶的活性分别随垫料添加和林下清除而增加。

结论

由于新鲜有机碳的输入，添加凋落物往往会改善土壤C的数量和质量，而林下土壤的清除则通过加速N矿化作用和缺乏林下植物的吸收来帮助增加N的供应。