东祁连山高寒草甸土壤酶活性及其化学计量特征对海拔和坡向的响应

Response of Soil Enzymes Activities and Their Stoichiometric Characteristics to Altitude and Aspect of Alpine Meadow in Eastern Qilian Mountains

研究高寒草甸微尺度海拔和坡向下土壤酶活性及其化学计量特征的变化对于探讨草地生态系统养分循环过程具有重要的生态学意义。以东祁连山高寒草甸为研究对象,分析了7个海拔(2800,3000,3200,3400,3600,3800,4000 m)和2个坡向(阴坡、阳坡)高寒草甸的土壤酶活性、化学计量特征变化规律及其与土壤理化因子之间的关系。结果表明:海拔和坡向的交互效应对土壤亮氨酸氨基肽酶(LAP)、β-葡萄糖苷酶(BG)、多酚氧化酶(PPO)和过氧化物酶(POD)酶活性、lnBG/ln(NAG+LAP)、lnBG/lnAP和ln(NAG+LAP)/lnAP有显著影响;LAP、AP、BG、POD、lnBG/ln(NAG+LAP)、lnBG/ln(NAG+LAP)随海拔的升高呈先升高后降低,β—1,4—乙酰基氨基葡萄糖苷酶(NAG)和PPO随海拔升高而降低;同一海拔,阳坡土壤AP、BG、POD、PPO酶活性低于阴坡,阳坡土壤NAG酶活性高于阴坡,海拔3800 m以下阳坡LAP酶活性低于阴坡,除海拔3000 m和4000 m外的其他海拔阳坡的土壤lnBG/ln(NAG+LAP)高于阴坡,海拔3000~3400 m的土壤lnBG/lnAP和海拔3000~3600 m的土壤ln(NAG+LAP)/lnAP在阳坡低于阴坡。相关分析发现,土壤酶活性及其化学计量特征不同程度受土壤C、N、P资源及土壤水分条件等的调控,土壤含水量和有机碳是影响土壤酶活性的主要因子。综上,土壤酶活性及其化学计量特征在微尺度海拔和坡向上具有差异性,且受土壤C、N、P资源及土壤水分条件的综合影响,以土壤含水量和有机碳尤为突出。

Studying the dynamic changes of soil enzyme activities and its stoichiometric characteristics at the micro-scale altitude and aspect of alpine meadows has important ecological significance for exploring the nutrient cycling process of grassland ecosystems.The alpine meadows in eastern Qilian Mountain was taken as the research object,and the changes of soil enzyme activities and its stoichiometric characteristics in seven altitudes and two aspects of alpine meadows,and their relationships with soil physical and chemical factors were analyzed.The results showed that the interactive effects of altitude and aspect had significant effects on soil LAP,BG,PPO,POD,lnBG/ln(NAG+LAP),lnBG/lnAP and ln(NAG+LAP)/lnAP.The LAP,AP,BG,POD,lnBG/ln(NAG+LAP)and lnBG/ln(NAG+LAP)first increased and then decreased with the increasing altitudes,while NAG and PPO decreased with the increasing altitudes.At the same altitude,The AP,BG,POD and PPO in the sunny aspect were lower than those in the shady aspect,and NAG in the sunny aspect were higher than that in the shady aspect,and LAP in sunny aspect under 3800 m were lower than that in the shady aspect,and lnBG/ln(NAG+LAP)in sunny aspect except 3000 and 4000 m were higher than that in the shady aspect,and lnBG/lnAP in sunny aspect under 3000 to 4000 m and ln(NAG+LAP)/lnAP in sunny aspect under 3000 to 3600 m were lower than that in the shady aspect.Correlation analysis found that,soil enzyme activity and its stoichiometric characteristics were regulated by soil C,N,P resources and soil moisture conditions to varying degrees,and soil moisture and SOC were the main factors affecting soil enzymes activities.In conclusion,soil enzymes activities and their stoichiometric characteristics were different in micro-scale elevations and slope directions,and were affected by soil C,N,P resources and soil moisture conditions,especially soil water content and SOC.