不同林龄退耕还林地森林土壤有机质和全氮变化

Change of soil organic matter and total nitrogen in different ages of forestland

选取贵州省兴义市三江口镇杉木人工林为试验区,以不同林龄下的土壤为研究对象,对不同林龄采取野外样地调查与实验测定土壤有机质和全氮含量进行分析。结果表明：土壤剖面（包括耕地）有机质和全氮含量均随土层深度的增加而减少,即0～20 cm〉20～40 cm〉40～60 cm土层,且在各土层之间的含量分布差异显著;有机质和全氮含量随林龄的增长而增加,且在各林龄之间含量分布差异显著;二者在土壤剖面和林龄分布上均存在波动,但高于耕地。不同林龄之间有机质和全氮含量的换算系数略有不同,在0.05～0.06之间。回归分析显示,各林龄（包括耕地）土壤有机质与全氮含量总体上有较显著的线性关系;林龄与有机质含量以及林龄与全氮含量在土壤剖面各层均存在显著的线性相关关系。

This study mainly studied the soil organic matter and total nitrogen of Chinese fir plantation in Sanjiangkou Town, Xingyi City, Guizhou Province. The results showed that in the soil profile（including farmland）,soil organic matter and total nitrogen contents decreased with soil depth increasing, 0～20 cm was higher than that in20～40 cm and 20-40 cm was higher than that in 40～60 cm, and the content distribution had significant difference among each soil layer. Soil organic matter and total nitrogen contents increased with forest age increasing, and content distribution had significant difference among each forest age. Both existed fluctuation in the distribution of soil profile and forest age, but higher than that in farmland. The conversion coefficients between soil organic matter and total nitrogen were different in different forest ages, was 0.05-0.06. Regression analysis showed that there was significant linear correlation between the content of soil organic matter and total nitrogen. We also got that there was significant positive correlation between forest age and the contents of soil organic matter and total nitrogen.