内蒙古典型草原土壤微生物生物量及其周转与流通量的初步研究

Preliminary Studies on Soil Microbial Biomass and Its Turnover in Typical Grasslands of NeiMongol Region

对内蒙古典型草原的土壤微生物数量和微生物生物量进行了测定和分析.典型草原不同生态分布类型的土壤微生物量大小有显著不同,土壤微生物的数量与生物量的分布规律基本一致,且与土壤有机质的分布相关联.土壤中微生物生物量碳在96.4～422.6mg/kg干土之间,占土壤有机碳的1.62%～4.82%.除沙地稀树草原土壤表层外,微生物垂直分布有随土层加深而递减的趋势.过度放牧将导致土壤微生物活性的下降.通过测定羊草草原土壤微生物量碳的动态变化,对微生物的通量和周转进行了分析,一个牧草生长季内微生物生物量碳的通量为52.69g/m2a,周转时间约为1.25年.

In different typical grasslands of NeiMongol,China,soil microbial biomass and biomass C were measured by the methods of dry-weight and extraction (FE). The results showed that soil microbial numbers and biomass in Leymus chinensis and Stipa grandis grassland were higher than those were in degenerative Artemisia frigida and sandy rare-tree grassland significantly.Microbial biomass has positive correlation with the amount of organic carbon in soil.Microbial biomass C was 96.4~422.6 mg/kg dry soil in the depth 0~20 cm in different grasslands.The ratio of microbial biomass C and organic C were 1.62%~4.82%. Overgrazing leads to significantly decrease of microbial biomass, while pasture fenced without grazing contribute to its restoring. The vertical distribution of microbial number and biomass showed that these was a trendency of decreased progressively with soil depths deepening except the surface layer of sandy grasslands. Through measuring the dynamic transformation of soil microbial biomass C,the turnover of biomass C was 52.69 g/m^2 in a growth season,the turnover time was about 1.25 a.