杉木人工林土壤活性有机质变化特征

在中国科学院会同森林生态实验站对第一代、第二代杉木林和地带性阔叶林土壤活性有机质主要组分进行了研究.结果表明,土壤活性有机质各组分含量均为杉木林低于阔叶林,而第二代杉木林又低于第一代杉木.第一代杉木林活性有机质总量、微生物生物量碳、水溶性有机碳和碳水化合物含量分别为18.79 g·kg^-1、421.7 mg·kg^-1、22.2 mg·kg^-1和136.3 mg·kg^-1,上述活性有机质组分在第二代杉木林中的含量分别是第一代杉木林的73.6%、87.9%、66.3%和3.2%,地带性阔叶林则分别为22.31 g·kg^-1、800. mg·kg^-1、361.1 mg·kg^-1和220.1 mg·kg^-1.相关性分析结果表明,土壤活性有机质各组分之间具有不同程度的相关性,其中土壤微生物生物量碳与其它活性有机质组分的相关性相对较高.

Dynamics of soil active organic matter in Chinese fir plantations

Soil active organic matter is the main source of soil nutrients, and plays an important role in the formation and stabilization of soil aggregate. Chinese fir (Cunninghamia lanceolata) is the most important fast-growing timber tree species in southern China, but its continuous plantation has caused soil deterioration. The study on the active fractions of soil organic matter under the first and second generation plantations of Chinese fir and the native broad-leaved forest at Huitong Experimental Station of Forest Ecology, Chinese Academy of Sciences, in Hunan Province showed that their contents were higher under native broad-leaved forest than under Chinese fir plantations, and higher under the first than under the second generation plantation. The content of soil active organic carbon (SAOC), microbial biomass carbon (MBC), water-soluble organic carbon (WSOC) and water-soluble carbohydrate (WSC) was 18.79 g x kg(-1), 421.7 mg x kg(-1), 252.2 mg x kg(-1) and 136.3 mg x kg(-1) under the first generation plantation of Chinese fir, and 22.31 g x kg(-1), 800.5 mg x kg(-1), 361.1 mg x kg(-1) and 220.1 mg x kg(-1) under the native broad-leaved forest, respectively. The corresponding values under the second generation plantation of Chinese fir were 73.6%, 87.9%, 66.3% and 53.2% of those under the first generation plantation of Chinese fir. The results also indicated that there existed some extent correlations among the active fractions of soil organic matter, and higher correlations between soil microbial biomass carbon and other active fractions of soil organic matter.