An estimation of soil microbial biomass as nutrient sink in forest soils.

目前已有两种方法用于了解森林土壤中土壤微生物生物量的作用。通过对近年来土壤微生物量估算的文献综述，证明氯仿熏蒸提取法适用于酸性土壤，适用于森林土壤微生物量的研究。研究了松栎混交林土壤微生物生物量的季节变化。森林在1994年被砍伐和烧毁。建立了次生林、清林和刀耕火种3个研究样地，比较了清林和刀耕火种的效果。有机层微生物生物量碳为2 ~ 12 mg g-1，表层微生物生物量碳为0.2 ~ 0.6 mg g-1。各样地夏季土壤微生物生物量均呈增加趋势。森林的砍伐减少了有机层的生物量，而矿质土的生物量略有减少。刈割后焚烧消除了表层土壤的有机层，减少了表层土壤的微生物量，特别是在坡底，燃烧强度较大。燃烧对土壤微生物生物量的影响在燃烧后14个月仍存在，表明刀耕火种对土壤有机质的分解有抑制作用。森林土壤中微生物量的测定可能是比土壤有机质含量更敏感的指标。

Two approach have been applied for understanding the role of soil microbial biomass in forest soils. A literature review of recent papers on estimation of soil microbial biomass proved that chloroform fumigation extraction method, which is applicable for acidic soils, is suitable for the soil microbial biomass study in forest soils.Seasonal changes in soil microbial biomass have been observed in a mixed secondary forest of pine and oak. The forest have been cut and burned in 1994. Three study plots have been established, secondary forest, clear-cut, and slash-burned, and the effects of clear-cutting and slash-burning were compared. Microbial biomass carbon in the organic layr was 2 to 12 mg g-1, and 0.2 to 0.6 mg g-1 in surface soil. Soil microbial biomass increased in summer in every plots. Clear-cutting of the forest reduced biomass in organic layr and slightly reduced in mineral soil. Burning after slashing eliminated soil organic layr and reduced soil microbial biomass in surface soils, especially in bottom of the slope, where intensive burning was observed. Effect of burning for the soil microbial biomass existed 14 months after burning, and it suggests that decomposition of organic matter in slash-burned area will be inhibited.The measurement of soil microbial biomass in forest soils may be more sensitive index than soil organic matter contents when the soil has been disturbed by clear-cutting and/or slash-burning.