摘要
灌丛化是影响草地土壤物质循环的重要生态过程。为探究草地灌丛化梯度变化对土壤酶活性的影响,本研究以青藏高原东缘3种典型灌丛高山绣线菊、小叶锦鸡儿、金露梅和未灌丛化草地为研究对象,分析不同灌丛化梯度下(未灌丛化、轻度灌丛化和重度灌丛化),0~10 cm、10~20 cm、20~40 cm、40~60 cm和60~80 cm土壤理化性质及蔗糖酶(sucrase)、脲酶(urease)、多酚氧化酶(polyphenol oxidase)、葡萄糖苷酶(glucosidase)、蛋白酶(protease)和纤维素酶(cellulase)活性。结果表明:灌丛化草地土壤0~20 cm土层中,pH和土壤有机碳(SOC)含量显著高于未灌丛化草地,土壤含水率(SWC)和全氮(TN)显著低于未灌丛化草地(P<0.05);蛋白酶、葡萄糖苷酶、纤维素酶、脲酶和蔗糖酶活性显著低于未灌丛化草地(P<0.05),多酚氧化酶活性在灌丛化与未灌丛化草地间无显著性差异,且不同灌丛化梯度下土壤酶活性随土层加深而降低;土壤酶活性在不同灌丛化梯度下和不同土壤深度发生变异的主要解释因子为SWC,分别可解释各土层土壤酶活性变异的41.2%、50.5%、37.1%、41.5%和26.0%;结构方程模型(SEM)表明,不同灌丛化梯度主要影响SOC、pH和SOC∶TN,对SWC和TN无显著影响,且不同灌丛化梯度可通过影响pH和SOC含量间接影响蔗糖酶、脲酶、葡萄糖苷酶、蛋白酶、多酚氧化酶和纤维素酶活性,灌丛化梯度不直接显著影响SWC(P>0.05),但SWC仍是影响6种酶活性的主要因子,其可直接正向影响该6种酶活性,也可通过负向影响土壤pH或正向影响SOC进一步影响TN,从而影响酶活性。因此,研究区草地灌木侵入导致土壤酶活性降低利于土壤有机碳固存。
Shrub encroachment is an important ecological process that affects soil material cycling in grasslands.This study investigated the effect of different shrub encroachment gradients on soil enzyme activity,compared to grassland with no shrubs present,under three common shrub species on the eastern margin of the Qinghai-Tibetan Plateau:Spiraea alpina,Caragana microphylla and Potentilla fruticosa.Soil physical and chemical properties and sucrase,urease,polyphenol oxidase,glucosidase,protease and cellulase activities were analysed in 0-10 cm,10-20 cm,20-40 cm,40-60 cm and 60-80 cm soil horizons with different shrub encroachment gradients(no shrubs,lightly and heavily shrub covered).It was found that the pH and soil organic carbon(SOC)contents were significantly higher and the soil water content(SWC)and total nitrogen(TN)were significantly lower(P<0.05)in the 0-20 cm soil layer of the shrub-covered grassland than when no shrubs were present.Similarly,the activities of protease,glucosidase,cellulase,urease and sucrase were significantly lower in shrub-covered than in grassland with no shrubs(P<0.05).The activity of polyphenol oxidase was not significantly different between shrub encroachment and no shrubs,and the activity of soil enzymes decreased with deepening of the soil layer at different shrub encroachment gradients.The main explanatory factor for the variation in soil enzyme activity across the different shrub encroachment gradients and soil depths was SWC,which explained 41.2%,50.5%,37.1%,41.5%and 26.0%,respectively,of the variation in activities of the five above-mentioned soil enzymes.Structural equation modeling(SEM)showed that different shrub encroachment gradients mainly affected SOC,pH and SOC∶TN,but not SWC and TN,and that different shrub encroachment gradients could indirectly affect sucrase,urease,glucosidase,protease,polyphenol oxidase and cellulase activities by affecting pH and SOC content.SWC is still the main factor affecting the activities of the six enzymes.SWC directly and positively influenced
作者
张东
侯晨
马文明
王长庭
邓增卓玛
张婷
ZHANG Dong;HOU Chen;MA Wen-ming;WANG Chang-ting;DENGZENG Zhuo-ma;ZHANG Ting(Institute of Qinghai-Tibetan Plateau,Southwest Minzu University,Chengdu 610041,China)
出处
《草业学报》
CSCD
北大核心
2023年第9期79-92,共14页
Acta Prataculturae Sinica
基金
国家自然科学基金项目(31600378,U20A2008)
中央高校(西南民族大学)基本科研业务费专项资金项目(ZYN2022052,2022NYX XS045)资助。
关键词
青藏高原高寒草地
灌丛化
灌丛化梯度
土壤酶活性
结构方程模型
Tibetan Plateau alpine grassland
shrub encroachment
shrub encroachment gradients
soil enzyme activity
structural equation model
