内蒙古典型草原土壤酶化学计量与限制性养分对放牧的响应  

Response of soil enzyme stoichiometry to grazing and identification of soil limiting nutrients in typical steppe of Nei Mongol,China

作　　者：李天琦 曹继容 柳小妮[2] 田思惠 兰波兰 邱颖 薛建国[1] 张倩[4] 褚建民[4] 张淑敏[1] 黄建辉[1] 李凌浩[1] 王其兵[1] LI Tian-Qi;CAO Ji-Rong;LIU Xiao-Ni;TIAN Si-Hui;LAN Bo-Lan;QIU Ying;XUE Jian-Guo;ZHANGQian;CHU Jian-Min;ZHANG Shu-Min;HUANG Jian-Hui;LI Ling-Hao;WANG Qi-Bing(State Key Laboratory of Vegetation and Environmental Change,Institute of Botany,Chines Academy of Sciences,China National Botanical Garden,Beijing 100093,China;College of Pratacultural Science,Gansu Agricultural University,Lanzhou 730070,China;University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute of Forestry,Chinese Academy of Forestry,Beijing 100091,China)

机构地区：[1]中国科学院植物研究所植被与环境变化国家重点实验室,国家植物园,北京100093 [2]甘肃农业大学草业学院,兰州730070 [3]中国科学院大学,北京100049 [4]中国林业科学院林业研究所,北京100091

出　　处：《植物生态学报》2025年第1期19-29,共11页Chinese Journal of Plant Ecology

基　　金：中国科学院战略性先导科技专项(A类)(XDA26020102);国家自然科学基金(42077056、42477519和41977046);国家重点研发计划(2023YFF404105)。

摘　　要：土壤胞外酶介导有机物分解,维持生态系统内养分循环,其活性及化学计量比是反映土壤养分可利用性、解析微生物资源限制的重要指标。然而放牧,特别是过度放牧引起的内蒙古典型草原退化对土壤胞外酶化学计量和养分限制特征的影响尚不清楚。该研究以内蒙古典型草原为研究对象,基于放牧强度梯度实验,分析了不同放牧强度下土壤胞外酶活性及其化学计量比的变化,并通过矢量模型解析了土壤养分限制特征。结果表明:(1)研究区域土壤水解酶活性在0–300 nmol·g^(–1)·h^(–1)范围内,与全球土壤酶库中的相应数值相比偏低。放牧强度显著影响α-葡萄糖苷酶、纤维素水解酶、木糖苷酶、纤维素二糖苷酶、β-1,4-N-乙酰氨基葡萄糖苷酶、亮氨酸氨基肽酶、酸性磷酸酶活性。随放牧强度的增加,酶活性动态呈现“双峰曲线”格局,分别在推荐放牧(RG)和中度放牧(MG)下出现活性峰值。(2)标准主轴回归分析表明,碳循环酶活性和氮循环酶活性、磷循环酶活性三者之间存在显著的线性关系。土壤酶碳:氮:磷化学计量比约为1:2.3:1.3,偏离了全球1:1:1的结果。(3)基于土壤酶化学计量比的矢量模型分析表明内蒙古典型草原放牧草地受到氮磷共同限制,磷限制更强烈,且随着放牧强度的增强,磷限制加剧。Aims Soil extracellular enzymes are crucial for soil organic matter decomposition and nutrient cycling.Soil enzyme activity and stoichiometry can provide insights into microbial resource limitations and soil nutrient availability.This study investigated the effects of grazing,particularly overgrazing that often leads to grassland degradation,on soil enzyme activity and stoichiometry,and identifies nutrient limitations in temperate grasslands.Methods We conducted grazing experiments with varying stock rates in a typical steppe of Nei Mongol,and investigated the changes in the activities and stoichiometric ratios of soil extracellular enzymes.Enzyme activities related to carbon(C),nitrogen(N),and phosphorus(P)cycling were analyzed,and a vector model was applied to determine soil nutrient limitations under different grazing intensities.Important findings 1)Soil hydrolase activities in the studied grassland ranged from 0 to 300 nmol·g^(-1)·h^(-1),which is relatively low compared with the global averages.Grazing intensity significantly impacted the activities of soil enzymes,includingα-glucosidase,cellulose hydrolysis,xylosidase,β-d-cellubiosidase,β-1,4-N-acetylamino-glucosidase,glycosaminidase,leucine aminopeptidase,and acid phosphatase.The enzymeactivities peaked under moderate grazing and recommended grazing.2)The Standardized Major Axis(SMA)regression analysis revealed strong linear relationships between the enzyme activities associated with C,N,and Pcycling.The soil enzyme C:N:P stoichiometric ratio was 1:2.3:1.3,deviating from the global average 1:1:1.3)Thevector model based on soil enzyme stoichiometry indicated that the grasslands were co-limited by N and P,with Plimitation becoming more pronounced as grazing intensity increased in Nei Mongol.

关 键 词：草地退化 放牧 土壤酶活性 养分限制 

分 类 号：R28[医药卫生—中药学]