贺兰山西坡不同植被类型土壤理化性质和酶活性特征

Characteristics of soil physicochemical properties and enzyme activities in different vegetation types on the western slope of Helan Mountain

【目的】探讨贺兰山西坡不同植被类型土壤理化性质对土壤酶活性的影响,为干旱区森林生态系统土壤酶活性变化、养分循环模式和调节机制研究提供参考依据。【方法】以贺兰山西坡土壤为研究对象,按照海拔梯度依次选择荒漠草原(海拔1349 m)、灰榆Ulmus glaucescens林(1905 m)、蒙古扁桃Amygdalus mongolica灌丛(2134 m)、油松Pinus tabuliformis林(2150 m)、青海云杉Picea crassifolia-山杨Populus davidiana混交林(2160 m)、青海云杉林(2635 m)和亚高山草甸(2664 m)等7种典型植被类型。每个植被类型设置3个重复样地,通过野外调查取样与室内分析相结合的方法,对土壤理化性质(含水率、容重、pH、有机碳、铵态氮、全氮、全磷、有效磷)和酶活性(β-葡糖苷酶、纤维二糖水解酶、α-葡糖苷酶、β-木糖苷酶、蔗糖酶、淀粉酶)进行测定,利用方差分析和冗余分析探明不同植被类型土壤酶活性质量分数差异,并分析其影响要素。【结果】0~10和10~20 cm土层土壤含水率、有机碳质量分数随海拔上升整体呈现上升趋势;而土壤容重随海拔上升在0~10与10~20 cm土层整体呈现下降趋势;土壤全磷、全氮、铵态氮和有效磷质量分数以及pH在0~10和10~20 cm土层中随海拔上升无显著变化规律;在不同海拔植被带0~10 cm土层土壤各酶活性高于10~20 cm土层;土壤纤维二糖水解酶与β-葡糖苷酶随海拔升高在0~10 cm土层呈上升趋势,淀粉酶活性随海拔升高在0~10 cm土层呈先升高后降低再升高趋势,而α-葡糖苷酶、β-木糖苷酶和蔗糖酶活性在不同植被带不同土层之间均变化幅度较小且差异不显著;在0~10与10~20 cm土层,土壤有机碳、全磷、铵态氮、含水率是土壤酶活性的主要影响因素。【结论】海拔梯度变化引起贺兰山西坡土壤理化性质显著变化,进而调控森林土壤酶活性沿海拔及土层分布的变化,其中土壤有机碳、pH及含水率是土壤酶活性的主要影响因素,能较好地解释土壤酶活性的海拔梯度差异。

[Objective]The aim is to investigate the effects of soil physicochemical properties in different vegetation types on soil enzyme activity on the western slope of Helan Mountain,and to provide a reference basis for the changes of soil enzyme activity,nutrient cycling patterns and regulatory mechanisms in forest ecosystems in dry areas.[Method]The seven vegetation types on the western slope of Helan Mountain were selected as the research object,which were desert grassland,Ulmus glaucescens forest,Amygdalus mongolica shrub,Pinus tabuliformis forest,Picea crassifolia-Populus davidiana forest and Picea crassifolia forest and subalpine meadow respectively from 1349 to 2664 m.Three replicate plots were set up for each vegetation type,and soil physicochemical properties(water content,bulk density,pH,organic carbon,ammonium nitrogen,total nitrogen,total phosphorus,and effective phosphorus)and enzyme activities(β-glucosidase,cellobiose hydrolase,α-glucosidase,β-xylosidase,sucrase,and amylase)were measured by field survey sampling and indoor analysis,with ANOVA and redundancy analysis.[Result]Soil water content and organic carbon mass fraction in the 0−10 and 10−20 cm soil layers of different vegetation zones at different altitudes showed an overall increasing trend with the rise in altitude;while soil bulk weight showed a decreasing trend with the rise in altitude in the 0−10 and 10−20 cm soil layers as a whole;soil total phosphorus,total nitrogen,ammonium nitrogen,effective phosphorus,and pH did not show any significant change patterns in the 0−10 and 10−20 cm soil layers with the rise in altitude;soil enzyme activities in the 0−10 cm soil layer were higher than those in the 10−20 cm soil layer.The activities of soil enzymes were higher in the 0−10 cm soil layer than in the 10−20 cm soil layer in different vegetation zones;Soil cellobiose hydrolase andβ-glucosidase showed an increasing trend with elevation in the 0−10 cm soil layer,amylase activity showed an increasing trend with elevation in the 0−10 cm soil layer,whileα-glucosidase,β-xylosidase,and sucrase activities showed small and non-significant variations in different soil layers in different vegetation zones;Soil organic carbon,total phosphorus,ammonium nitrogen,and water content were the main factors affecting soil enzyme activities in the 0−10 and 10−20 cm soil layers.In the 0−10 and 10−20 cm soil layers,soil organic carbon,total phosphorus,ammonium nitrogen,and water content were the main influencing factors of soil enzyme activities.[Conclusion]Changes in altitudinal gradient caused significant changes in soil physicochemical properties on the western slope of Helan Mountain,which in turn regulated the changes in forest soil enzyme activity along the distribution of altitude and soil layers.Soil organic carbon,pH and water content were the main factors influencing soil enzyme activity,and could better explain the differences in the altitudinal gradient of soil enzyme activity.