东祁连山高寒草地土壤微生物碳氮研究

在青藏高原东祁连山段,嵩草草地、金露梅灌丛草地、珠芽蓼-嵩草草地、高山柳-金露梅灌丛草地、禾草草地、沼泽草地上,分层(0~10 cm,10~20 cm)采集了土壤样品,分析了土壤有机C、全N和微生物量C、N含量的关系。结果表明:在一定范围内,青藏高原东祁连山段高寒草地土壤微生物量C、N含量与土壤有机C、全N表现出了很好的相关性。不同草原类型的表层土壤有机C含量顺序为:高山柳-金露梅灌丛草地>珠芽蓼-嵩草草地>嵩草草地>金露梅灌丛草地>沼泽草地>禾草草地;土壤全N含量顺序为:嵩草草地>金露梅灌丛草地>高山柳-金露梅灌丛草地>珠芽蓼-嵩草草地>沼泽草地>禾草草地。土壤微生物量C随着土层深度的增加而减少,微生物量C变化在251.6~1 562.5 mg/kg之间,微生物量N变化在18.5~50.9 mg/kg之间,微生物量C/N在12~32之间。土壤微生物量碳(Cmic)占土壤有机碳的(Corg)的比例在0.3%~1.7%之间。不同草原类型的土壤微生物量C、N含量差异较大。

Soil microbial carbon and nitrogen contents of different kinds of alpine grassland in the Eastern Qilian mountains

The soil samplings at two layers(0～10 cm,10～20 cm) of six distinct alpine grassland forms in the Eastern Qilian Mountains were collected in July,2004.The soil organic carbon(C)and total nitrogen N(N) were analyzed,and the soil microbial biomass C(C_(mic))andN(N_(mic))were determined by an extraction method.The results showed as follows:the contents of C_(mic) and N_(mic) of the alpine grassland showed significant correlations with soil organic carbon and total nitrogen.Soil organic carbon in the soil layer 0～10 cm showed a decreasing trend as: Salix cupularis-potentilla fruticosa shrubs> Polygonum viviparum-Kobresia meadow>Kobresia meadow>Potentilla fruticosa shrubs>wet meadow>grass steppe.Total nitrogen in the soil layer 0～10 cm showed a decreasing trend as: Kobresia meadow> potentilla fruticosa shrubs>Salix cupularis-potentilla fruticosa shrubs> Polygonum viviparum-Kobresia meadow>Grass steppe.Soil microbial biomass C and N of the surface soil were more than that of deeper layer of soil.Soil microbial biomass C and N ranged from 251.6～(1562.5 mg/kg) and 18.5～50.9 mg/kg respectively,C_(mic)/N_(mic) from 12～32,and C_(mic)/C from(0.3 %)～(1.7 %).Soil microbial biomass C and N dive rsed with different types of grassland.Effect of grazing on soil microbial biomass depended on grassland types and grazing intensity.