西藏“一江两河”流域生态系统服务变化及权衡与协同关系研究

为使环境资源得到高效配置,明晰生态系统服务间权衡关系是重要前提。以一江两河流域为对象,基于InVEST模型对该区1990—2018年的土壤保持、水源涵养和固碳服务进行动态评估,并采用相关分析法探讨了流域、县域尺度下各服务间的权衡关系。结果表明:(1)1990—2018年,土壤保持量和碳储量呈波动增加趋势,产水量呈减少趋势。单位面积土壤保持量、产水量和碳储量的高值区均分布在流域东部的拉萨河河谷地区。(2)流域尺度下,2010年水源涵养服务与固碳服务间表现出权衡关系,其余年份各服务间均呈现出协同关系; 县域尺度下,各服务间关系也多为协同关系,但具有较强的空间异质性。(3)热点制图显示,1990—2018年1类区占比最大且呈增加趋势,主要地类为低植被覆盖草地; 0类和2类区占比增加,主要地类分别为沙地和高植被覆盖草地; 3类区占比有所减少,主要地类为高植被覆盖草地和灌木林。由此可得,研究区3种生态系统服务具有较强的时空异质性,各服务间以协同关系为主,且随时空变化而发生着强弱变化。

Research for Change of Ecosystem Service and the Tradeoff-Synergy Relation of the YLN Basin in the Tibet Autonomous Region

For the effective allocation of environmental resources,clarifying the tradeoff relations among the ecosystem services is the important premise.The YLN Basin(the Basin of Yarlung Tsangpo River,Lhasa River,and Nianchu River)is the research case.Based on InVest model,this regional soil conservation,water conservation,and carbon storage between 1990 and 2018 were evaluated dynamically.This paper also adopted the other related analysis to discuss the tradeoff relations among the different services on the scales of basin and county respectively.The results show that:(1)from 1990 to 2018,the soil conservation and the carbon storage showed a fluctuating increasing trend,water production reduced;the high values of soil conservation,water production and carbon storage in per unit area all distributed in the Lhasa River valley in the eastern basin;(2)on scale of basin,there was a trade-off nexus between water conservation service and carbon storage service in 2010,and the other services all manifested synergistic nexus in the other years;on the scale of county,the relations of services mainly were occupied by synergistic nexus,nonetheless it possessed relatively intensive spatial heterogeneity;(3)the hotspot map illustrated that category 1 had largest proportion and it was increasing between 1990 and 2018,the main land type was low vegetation covered meadow;the proportions of the categories of 0 and 2 increased,the main land types were sandy land and high vegetation covered meadow;the proportion of category 3 reduced,the main land types were high vegetation covered meadow and shrubbery.Therefore,the 3 kinds of ecosystematic services have the relatively intensive spatial heterogeneity,and the synergistic nexus is the major one among the services that is alterable following the spatiotemporal change showing different degrees.