青海湖流域高原鼠兔扰动对土壤养分及微生物量碳氮的影响

Effects of plateau pika's disturbance on soil nutrients,microbial biomass C and N of different land surface types in Qinghai Lake watershed

为了揭示高原鼠兔扰动对高寒草甸土壤养分和微生物量碳氮的影响,在青海湖流域进行定点采样分析,研究了高原鼠兔扰动前后不同地表类型(草地、新鼠丘、旧鼠丘和禿斑地)土壤养分的垂向分异和水平差异.结果表明:1)高原鼠兔扰动能在短时间内增加土壤养分含量和速效养分释放量,不同土层全氮、碱解氮、全磷、有效磷、全钾和速效钾质量分数的差异均非常显著(P<0.01),不同地表类型全氮、碱解氮、有效磷、全钾和速效钾质量分数的差异显著(P<0.05),但全磷质量分数的差异不显著(P>0.05);2)高原鼠兔扰动能在短时间内增加土壤微生物量碳氮质量分数,并使其垂向分布更加均匀,随着时间推移土壤微生物量碳氮质量分数迅速下降,不同土层微生物量碳氮质量分数的差异均非常显著(P<0.01),不同地表类型微生物量碳质量分数的差异显著(P<0.05),但微生物量氮质量分数的差异不显著(P>0.05);3)高原鼠兔扰动主要通过改变土壤密度和土壤粉粒、地上生物量、土壤含水的质量分数对土壤营养成分产生影响,高原鼠兔扰动后,土壤环境在短期内得到改善,伴随土壤侵蚀的发生多种营养元素流失,土壤总体品质逐渐下降.

To investigate effects of plateau pika＇s disturbance on soil nutrients（total N,available N,total P,available P,total K,and available K）and microbial biomass carbon and nitrogen in alpine meadow,field fixed-point experiments were carried out in the Qinghai Lake watershed.Vertical and horizontal differences in soil nutrients of different land surface types（grassland,new mounds,old mounds and bare land）were analyzed.It was found that disturbance of plateau pika increased contents of soil nutrients and available nutrients in a short time.Total N,available N,total P,available P,total K and available K in different soil layers were significantly different（P〈0.01）.Total N,available N,available P,total K and available K in different land surface types were also different（P〈0.05）,no significant difference was found for total P among different land surface types（P〈0.05）.Plateau pika＇s disturbances increased soil microbial C and N and made them more evenly distributed in a short time.However,their contents will decrease rapidly with time.The differences in soil microbial C and N contents in different soil layers were found to be statistically significant（P〈0.01）.There were differences in soil microbial C contents among different land surface types（P〈0.05）,but there was no difference in soil microbial N contents（P〈0.05）,Disturbance of plateau pika was found to mainly affect soil nutrient composition by varying soil bulk density,soil powder content,aboveground biomass and soil gravimetric water content.Plateau pika＇s disturbances could improve soil quality very quickly,soil quality then decreased gradually with loss of various nutrient elements.This study would help to understand how plateau pika＇s disturbance influences soil quality of alpine meadow,and provide a key reference for management and protection of grassland in Qinghai Lake watershed.