天山北坡中段放牧草地生态系统功能权衡关系的研究

Study on the Trade-offs among Ecosystem Functions of the Grazing Land in the Middle Part of Northern Slope of the Tianshan Mountains

草地生态系统功能保障着人类的生存发展,是草地畜牧业的重要基础。以天山北坡中段草地为研究对象,设置轻牧(LG),重牧(HG)和禁牧(CK)3种处理,基于野外植被调查和室内分析及高通量测序技术,利用单功能法和平均值法得到草地生产力、土壤碳贮存、土壤养分循环、生物多样性和土壤微生物量5种草地生态系统功能以及生态系统多功能性(EMF),并使用均方根偏差法(RMSE)分析放牧干扰下草地生态系统功能及多功能性之间的权衡关系。结果表明,相较于CK,HG显著降低草地生态系统功能及多功能性(P<0.05)。放牧可以改变生态系统功能之间原有的权衡关系,但土壤养分循环功能与土壤碳贮存功能的权衡关系对放牧响应不敏感。根据多项功能权衡协同分析的结果显示,生态系统功能ERMSD值为LG(E_(RMSD)=0.07)<HG(E_(RMSD)=0.10)<CK(E_(RMSD)=0.12),这意味着在LG处理下的草地生态系统功能间的均衡性和协调性最优。综上,本研究区最适宜放牧强度为LG,有利于最大程度地提高草地生态系统功能间的协同效应。

Functions of grassland ecosystem secure survival and development of human being and it is the important foundation of grassland animal husbandry.This research focused on the grassland in the middle section of the northern slope of the Tianshan Mountains.Grassland productivity,soil carbon stor-age,soil nutrient cycling,biodiversity,and soil microbial biomass from field vegetation survey,indoor analysis,and high-throughput sequencing technology were calculated with single function method and mean value method as represent parameters for ecosystem function and multifunctionality.Furthermore,the root mean square error(RMSE)method was approached to analyze the trade-offs between ecosystem function and multifunctionality under intensities of light grazing(LG),heavy grazing(HG),and grazing prohibition(CK).Results revealed that HG reduced grassland ecosystem function and multifunctionality significantly compared with CK(P<0.05).Grazing can change the original trade-offs between various ecosystem functions,whereas the response of the trade-offs between EF-SN and EF-C to grazing is not sensitive.According to the synergistic analysis of multiple functional trade-offs,the E_(RMSD) value of ecosys-tem function had the trend of LG(E_(RMSD)=0.07)<HG(E_(RMSD)=0.10)<CK(E_(RMSD)=0.12),indicating that the balance and coordination between grassland ecosystem functions were the best under LG treat-ment.In summary,the most suitable grazing intensity in this study area is light grazing,which can amplify the synergistic effects among grassland ecosystem functions the most.The results will provide a theoretical reference for the protection and restoration of degraded grassland ecosystems in the northern slope of Tian-shan Mountains.