季节性雪被对高寒草甸土壤微生物量碳、氮动态的影响

Effects of Seasonal Snow Cover on the Dynamics of Soil Microbial Biomass Carbon and Nitrogen in an Alpine Meadow

[目的]探索季节性雪被对高寒草甸土壤微生物量碳、氮动态的影响。[方法]根据自然雪被分布的差异,在青藏高原东南缘的高寒草甸生态系统中设置3条雪梯度样带(深雪、中雪和浅雪),于2008年秋冬过渡期监测各样带中土壤温度和含水量,并研究不同雪梯度下土壤微生物量碳、氮的动态变化。[结果]月均土温、每月日最高土温均值、每月日最低土温均值都分别与雪厚度呈显著二次函数关系。雪厚度和土壤温差对土壤含水量具有显著影响。在秋冬过渡期末,深雪梯度中土壤微生物量碳先显著升高又显著降低;浅雪梯度中,土壤微生物量氮在稳定的浅雪被(约10cm)形成后显著增加。雪被下土壤微生物量碳、氮含量都分别与土壤温度呈显著的三次函数关系。[结论]季节性雪被对土壤温度和土壤含水量有显著影响,也引起高寒草甸土壤微生物量碳、氮动态的明显差异。

[Objective]The effects of seasonal snow cover on the dynamics of soil microbial biomass carbon and nitrogen in the alpine meadow were explored.[Method]Based on the natural distribution difference of snow cover,three snow regimes in the alpine meadow ecosystem at the eastern margin of Qinghai-Tibetan Plateau were set up,including a shallow and short duration snowpack（SS）,a moderate snow depth and medium duration snowpack（MS）,as well as a deep and long duration snowpack（DS）.The soil temperature and soil moisture content in different snow regimes in the during the autumn-winter transition stage of 2008 were measured.And the dynamic changes of soil microbial biomass carbon and nitrogen in different snow regimes were studied.[Result]The average monthly soil temperature,the daily maximum soil temperature mean in each month,the daily minimum soil temperature mean in each month all showed significant quadratic function relation with snow depth.The snow depth and soil temperature difference had significant effects on the soil moisture content.At the end of autumn-winter transition stage,the soil microbial biomass carbon in DS declined markedly after a significant increase.The soil microbial biomass nitrogen in SS increased significantly after stable SS（about 10 cm） was formed.The contents of soil microbial biomass carbon and soil microbial biomass nitrogen both showed the significant cubic function relation with soil temperature.[Conclusion]Because seasonal snow cover affected soil temperature and soil moisture significantly,the significant difference of the dynamics of soil microbial biomass carbon and soil microbial biomass nitrogen in the alpine meadow were induced.