贵州喀斯特地区植被修复对土壤氮素的影响

喀斯特地区正开展一系列的生态恢复工程措施,研究生态修复过程与土壤氮循环过程的交互作用对喀斯特地区生态系统植被修复具有重要的科学意义。本研究以贵州草海保护区不同地貌(非喀斯特、喀斯特及植被修复)为研究对象,采用时空互代法研究地貌环境对土壤氮组分(全氮、碱解氮、硝态氮、铵态氮)分布特征的影响,并分析它们与土壤理化因子之间的关系。结果表明：(1)非喀斯特样带氮含量与喀斯特样带对比,前者土壤氮素累积呈现向上富集的规律,在土壤表层呈表聚现象,土壤硝态氮和铵态氮含量均高于喀斯特样带,铵态氮占无机氮主要部分；(2)喀斯特样带由于地质条件、植被覆盖度低、凋落物归还量少和土壤侵蚀导致活性有机碳较低,进而影响土壤氮素累积；植被恢复初始阶段,土壤中氮素供应强度会得到改善,土壤硝化和氨化速率均有显著提升,土壤侵蚀作用减弱,土壤对养分的固持能力加强,进而土壤硝态氮和铵态氮含量显著高于喀斯特样带。

Effect of Vegetation Restoration on Soil Nitrogen Distribution in Karst Area of Guizhou Province

A series of ecological restoration engineering measures are being carried out in karst areas. Studying the interaction between ecological restoration process and soil nitrogen cycle process has important scientific significance for ecosystem vegetation restoration in karst area. This study focused on different landforms (non-karst, karst and vegetation restoration) in Caohai Nature Reserve of Guizhou Province. the effects of geomorphological environment on the distribution characteristics of soil nitrogen components (total nitrogen, alkali-hydrolyzable nitrogen, nitrate nitrogen and ammonium nitrogen) were studied by spatio-temporal substitution method. the relationship between them and soil physical and chemical factors was analyzed. The results showed that: (1) Compared with the non-karst zone, the soil nitrogen accumulation of the non-karst zone showed the law of upward enrichment, and the soil surface layer showed a phenomenon of surface accumulation, and the contents of soil nitrate and ammonium nitrogen are higher than those of the karst zone. Ammonium nitrogen accounts for the main part of inorganic nitrogen. (2) the karst belt has low active organic carbon due to geological conditions, low vegetation coverage, low litter return and soil erosion, which in turn affected soil nitrogen accumulation. In the initial stage of vegetation restoration, the intensity of nitrogen supply in soil was improved, the rates of soil nitrification and ammoniation was significantly increased, the effect of soil erosion was weakened, and the retention capacity of soil nutrients was strengthened. the contents of soil nitrate and ammonium nitrogen were significantly higher than those in karst belt.