草地生物结皮分布格局影响坡面水土流失的动力机制  

Dynamical mechanisms of soil and water loss as influenced by the distribution pattern of biocrusts in grassland

作　　者：吉静怡 赵允格[1,2,3] 郭雅丽 张万涛 JI Jingyi;ZHAO Yunge;GUO Yali;ZHANG Wantao(State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,The Research Center of Soil and Water Conservation and Ecological Environment,Chinese Academy of Sciences and Ministry of Education,Yangling 712100,China;Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling 712100,China;College of Soil and Water Conservation Science and Engineering,Northwest A&F University,Yangling 712100,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院教育部水土保持与生态环境研究中心,黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100 [2]中国科学院水利部水土保持研究所,杨凌712100 [3]西北农林科技大学水土保持科学与工程学院,杨凌712100 [4]中国科学院大学,北京100049

出　　处：《农业工程学报》2025年第6期137-144,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(42377357)。

摘　　要：干旱半干旱区的生物结皮与草本植被共存,具有特定的分布格局,共同影响草地水土流失。然而,目前鲜有研究关注草地生态系统中生物结皮分布格局对水土流失的影响及作用机制,妨碍了干旱半干旱区水土流失的准确评估。研究利用模拟降雨试验,在相近的草本植被盖度下,探讨了生物结皮分布格局对水土流失的影响及其动力机制。结果表明:1)不同盖度生物结皮景观格局指数差异显著。生物结皮盖度从20%~35%增至35%~50%,其斑块边缘密度和连结度分别增加了1.70和1.04倍,分离度降低了95.4%,斑块形状趋于复杂化,破碎程度减少;2)生物结皮分布格局显著影响水土流失过程,且表现出明显的阈值效应。当生物结皮斑块分离度达到35.89(对应生物结皮盖度约44.7%)时,其对坡面产流产沙过程的影响显著降低。3)当生物结皮分离度小于35.89时,生物结皮分布格局通过影响坡面侵蚀动力显著改变水土流失过程。其中,分离度是影响水土流失过程的主要格局因子,随分离度增加(即斑块越破碎),径流流速、雷诺数和径流功率增加,导致径流率和土壤侵蚀速率上升。该研究揭示了生物结皮及其分布格局在草地水土保持中的重要作用,为半干旱区水土保持管理和评估提供了科学依据和管理策略。Biological soil crusts(biocrusts)coexist with the herbaceous vegetation in the arid and semi-arid regions.Unique patterns of distribution has formed to collectively influence the soil and water erosion.These ecosystems can be characterized by the unstable soil structures and sparse vegetation cover.The stabilizing functions of biocrusts and vegetation can be expected to mitigate the sediment loss.The hydrological dynamics can also be used to regulate the soil infiltration.However,it is still remained unknow on the role of biocrust distribution patterns in soil erosion,particularly in grassland ecosystems.Therefore,it is a high demand to accurately assess the soil erosion risks for the effective management strategies in these regions.In this study,the simulated rainfall experiments were conducted under consistent vegetation coverage.A systematic investigation was implemented to explore the patterns of biocrust distribution on the soil and water erosion processes under different coverage levels.The underlying dynamic mechanisms of soil and water loss were elucidated under the distribution pattern of biocrusts in grassland.The results showed that:1)The pattern indices of distribution were significant differences in biocrust with the different coverages.Specifically,the edge density(ED)and Patch cohesion index(COHESION)increased by 1.70 and 1.04 times,respectively,as the biocrust coverage increased from 20%-35%to>35%-50%.Conversely,the splitting index(SPLIT),which represented the degree of patch fragmentation,decreased by 95.4%,indicating the decreasing patch fragmentation.The biocrusts were formed more cohesive and less fragmented patches,as the coverage increased.Some implications were gained for the overall stability and hydrological function of the landscape.2)The distribution of biocrust was depended significantly on the soil erosion.Importantly,there was the outstanding threshold impact of the biocrust distribution pattern on the runoff and sediment yield.The impact of biocrust distribution on the runoff and se

关 键 词：土壤侵蚀 植被 景观格局指数 产流产沙特征 水力学参数 

分 类 号：S157.1[农业科学—土壤学] S181[农业科学—农业基础科学]