Effect of alterations in forest litter inputs on soil C and N storage distribution in Pinus yunnanensis forest in central Yunnan Plateau

为了更好地理解土壤碳氮对枯落物输入变化的响应，通过枯落物添加与去除实验（DIRT）对滇中高原云南松林枯落物输入变化对土壤碳氮储量及其分布格局的影响进行了研究。2018年3月至2019年2月分别设置6种枯落物输处理，分别为对照（CO）、去除枯落物（NL）、双倍枯落物（DL）、去除根系（NR）、无输入（NI）以及去除有机层与A层（O/A-Less），研究了不同处理条件下土壤剖面上碳氮储量的分布规律。研究结果表明：（1）不同处理全碳储量为134.49-170.92 t/hm²，全碳储量在不同处理间表现为：S_C（NL）=170.92 t/hm² > S_C（CO）=168.10 t/hm² > S_C（NR）=153.26 t/hm² > S_C（NI）=147.20 t/hm² > S_{C（O/A-Less）}=143.54 t/hm² > S_C（DL）=134.49 t/hm²，不同处理0-20 cm土层全碳储量占0-60 cm土层全碳储量的40.86%-53.56%；不同处理全氮储量表现为：S_N（CO）=11.83 t/hm² > S_N（NL）=9.70 t/hm² > S_N（DL）=8.70 t/hm² > S_N（NR）=8.35 t/hm² > S_{N（O/A-Less）}=8.21 t/hm² > S_N（NI）=8.09 t/hm²。不同处理0-20 cm土层的全氮储量占0-60 cm土层全氮储量的39.28%-46.04%。云南松林地枯落物添加去除实验发现去除枯落物短期内可以增加土壤碳储量，其他处理均在一定程度上减少了土壤碳氮储量。（2）地上枯落物输入对表层（0-20 cm）土壤碳氮影响显著，根系输入对深层（20-40 cm）土壤碳氮影响显著；（3）土壤C、N存在耦合关系，不同处理土壤全碳含量与全氮含量极显著正相关，并且土壤全碳含量与土壤各化学计量比均呈极显著正相关关系；土壤容重与土壤碳氮含量具有极显著负相关关系。;In order to well understand the response of soil C and N variation to alterations in forest litter the detritus input and removal treatment (DIRT) was used to reveal the response of soil carbon and nitrogen to alterations in forest litter in Pinus yunnanensis forest in central Yunnan Plateau. Six treatments of litter input and removal were established, which were normal litter inputs (CO), no litter (NL), double litter (DL), no roots (NR), no inputs (NI), and remove the organic layer and layer A (O/A-Less) to study the response of soil carbon and nitrogen variation to alterations in forest litter Pinus yunnanensis forest. The results showed that (1) the soil total carbon storage decreased in the order:S_C(NL)=170.92 t/hm² > S_C(CO)=168.10 t/hm² > S_C(NR)=153.26 t/hm² > S_C(NI)=147.20 t/hm² > S_C(O/A-Less)=143.54 t/hm² > S_C(DL)=134.49 t/hm². The soil total nitrogen storage decreased in the order:S_N(CO)=11.83 t/hm² > S_N(NL)=9.70 t/hm² > S_N(DL)=8.70 t/hm² > S_N(NR)=8.35 t/hm² > S_N(O/A-Less)=8.21 t/hm² > S_N(NI)=8.09 t/hm². Soil total carbon and nitrogen storage decreased significantly in all treatments compared to CO, although soil total carbon storage increased slightly in NL. (2) The aboveground litter input had significant effects on soil total carbon and nitrogen in the surface layer 0-20 cm of soil, and the underground litter input had significant effects on soil total carbon and nitrogen in the deep layer 20-40 cm of soil. (3) There is a coupling relationship between soil C and N in forest systems. There was a significant positive correlation between total carbon and nitrogen of soil. Bulk density had significant effect on carbon and carbon of soil.