土地利用方式对会仙岩溶湿地土壤营养元素含量的影响

结合桂林会仙岩溶湿地生态环境情况，研究了湿地不同土地利用方式对土壤有机碳、总磷、总氮等营养元素含量的变化和影响，结果表明：（1）土壤中磷元素的含量，住宅用地＞水田＞岩溶湿地（原生湿地）＞未利用荒地（闲置地）＞坑塘水面（鱼塘），全钾最高的是未利用荒地（闲置地），有机质含量最高的是岩溶湿地（原生湿地），各形态的氮元素中硝态氮含量最多的是住宅用地，全氮最高的是未利用荒地；（2）土地利用与土地覆被的变化加剧了土壤有机碳、硫、氮磷的流失，导致湿地退化，未利用荒地退化指数-0.128、鱼塘退化指数-0.177、水田退化指数0.137、住宅用地退化指数0.39；（3）退化的原因是主要是人类活动的过分干扰。因此，有必要科学合理地对湿地进行恢复。

Impact of different land use modes on soil nutrients of Huixian karst wetland

Combined with the ecological environment of Huixian karst wetland in Guilin City, the authors studied the impact of different land use modes on soil nutrients of wetland such as organic carbon, total nitrogen and total phosphorus. The results of study are as below：（1）Contents of phosphorus in soil：Residential land〉Paddy field〉Karst wetland（native wetland）〉Unused land（Idle land）〉Pond（fish pond）;unused land（Idle land）has the highest total potassium; karst wetland（native wetland）has the highest organic contents; residential land has the highest nitrate nitrogen content;unused land has the highest total nitrogen;（2）Change of land use and land cover accelerate losses of organic carbon, sulfur, nitrogen and phosphorus in soil, and lead to degradation of wetlands, of which the degradation index is-0.128 for unused land;-0.177 for fish pond;0.137 for paddy field;0.39 for residential land;（3）Excessive interference of human activities is the major cause for land degradation, so scientific and rational restoration of wetland is necessary.