北亚热带次生栎林与火炬松人工林土壤微生物生物量碳的季节动态

在南京林业大学下蜀森林生态定位研究站次生栎林和火炬松人工林内,采用随机区组设计,连续两年测定了林下土壤微生物生物量碳、土壤温度、土壤湿度和林地凋落物输入量.结果表明:两种林分的土壤微生物生物量碳呈明显的季节性波动,均在植物生长旺季维持在较低水平,而在植物休眠季节维持在较高水平;在0～10 cm土层内,火炬松林和次生栎林土壤微生物生物量碳变幅分别在267.8～459.8 mg·kg-1和278.6～467.8 mg·kg-1;土壤微生物生物量碳与土壤温度之间具有显著的负相关关系,而与森林地上凋落物输入量、土壤湿度无显著相关关系.说明该区域土壤微生物生物量碳的季节波动可能与土壤中有效碳及其它土壤养分的可利用状况、植物根系对营养的竞争以及林木的生长节律有关.

Seasonal fluctuation of soil microbial biomass carbon in secondary oak forest and Pinus taeda plantation in north subtropical area of China

With random block experimental design, the soil microbial biomass carbon, soil temperature, soil moisture, and litterfall input in secondary oak forest and Pinus taeda plantation were measured in successive two years at the Xiashu Experimental Forest of Nanjing Forestry University. The results showed that in the two stands, soil microbial biomass carbon had an obvious seasonal fluctuation, being lower in plant vigorous growth season but higher during plant dormancy. The microbial biomass carbon in 0-10 cm soil layer ranged from 267.8 mg x kg(-1) to 459.8 mg x kg(-1) in P. taeda plantation and from 278.6 mg x kg(-1) to 467.8 mg x kg(-1) in secondary oak forest. Soil microbial biomass carbon had a significant negative correlation with soil temperature, but no significant correlations with soil moisture and litterfall input. It was suggested that the seasonal fluctuation of soil microbial biomass carbon in test stands could be more related to the availability of soil carbon and other nutrients, competition of plant roots for soil nutrients, and plant growth rhythm.