广西平果县退耕还林土壤环境效应及生态效益价值估算

Environmental effect of returning farmland to forest and its ecological value estimation in Pingguo County,Guangxi Zhuang Autonomous Region

通过采样与分析,对广西壮族自治区平果县石质山区退耕还林林下土壤进行了研究,分析了退耕还林地与农田土壤理化性质的差异,以及典型样地中不同植被恢复措施的土壤物理化学状况,并利用价格替代法、影子工程法评估平果县退耕还林工程的理论生态效益。结果表明:退耕还林10年后,土壤剖面结构逐渐完善,土壤容重减小,总孔隙度、毛管孔隙度、土壤含水量增大;土壤有机质含量增加15%;全氮元素增加不明显。土壤质量恢复效益最大的是早熟桃林地与任豆林地。不同类型的植被,土壤速效养分的差异大于土壤全量元素的差异。从拦蓄保护水资源价值与减少土壤肥力损失价值两方面计算平果县退耕还林工程土壤生态效益价值超过21亿元。

Based on sampling and analyses,the effects of returning farmland to forest on soil characteristics were investigated in Rocky Mountain,Pingguo County,Guangxi Zhuang Autonomous Region.The difference in physicochemical properties between forest land and agricultural field and the physicochemical properties of soil in typical samples under different vegetation restoration measures were analyzed.The theory ecological effect of converting farm land to forest land was estimated using price substitution method and shadow project approach.The results showed that the soil profile structure gradually improved,the soil bulk density reduced,and the total porosity,capillary porosity and water content increased after returning farmland to forest.Meanwhile,the soil organic content increased for 15% and there was no significant increase in total nitrogen content.The soil quality recovery benefit was the largest in precocious peach land and Zenia insignis land.Under different types of vegetation,the difference in soil available nutrient was larger than soil total elements.The ecological benefit values were more than 2.1 billion yuan in protection of water resource and decrease the loss of soil fertility.