基于城市化梯度的中国西南地区生态系统服务权衡与协同

通过构建生态系统服务量化模型与权衡协同模型，刻画中国西南地区关键生态系统服务的时空演变过程，并结合空间静态和时间动态尺度定量测度生态系统服务之间的相互关系，进一步探究西南地区不同城市化梯度下生态系统服务之间权衡协同作用的异质特征，揭示城市化梯度下生态系统服务权衡的形成机制。研究结果表明：①近20年西南地区耕地和草地面积显著减少，建设用地和水域面积分别增长了141.19%和34.6%，其中贵州省城市扩展特征突出，四川省耕地减少最为明显。研究区生境质量指数和产水量呈下降趋势，土壤保持、粮食生产和碳储存三种生态系统服务有所增加；②动态视角下研究区61%的面积土壤保持服务和产水量服务存在权衡关系，碳储存和另外四种生态系统服务之间有着大面积（>70%）的不显著关系；③静态视角下，不同的城市化梯度区生态系统服务呈现显著的异质特征。非城市化地区与整个研究区情况类似，但土壤保持和碳储存之间的相关性逐渐减弱。城市化快速地区生态系统服务之间的权衡协同关系最为显著，特别是碳储存和生境质量的相关性最高（R²=0.541），以往城市化地区生态系统服务的相互作用强度弱于其他两类区域，但两两生态系统服务之间均呈现正相关；④城市建设用地的快速扩张导致生态系统服务下降，尤其是对生境质量具有显著的负面效应，城市化快速地区生态服务之间的相互作用表现得更为剧烈。林地面积大幅增加使得土壤保持服务有所增加，在山区表现尤为明显，而城市化能够引起碳储存和生境质量强烈的协同下降。

Tradeoffs-synergies analysis of ecosystem services along urbanization gradient in Southwest China

By constructing quantitative model and tradeoff/synergic model of ecosystem services, the spatio-temporal evolution process of key ecosystem services in Southwest China was investigated. Based on the spatial static and temporal dynamic scale, the relationship between ecosystem services was quantitatively measured to further explore heterogeneous characteristics of tradeoff/synergic effects between ecosystem services in southwest region and reveal the formation mechanism of ecosystem services tradeoffs under different urbanization gradient. The results showed that (1) in the past 20 years, the area of cultivated land and grassland in Southwest China decreased significantly, while the area of construction land and water increased by 141.19% and 34.6%, respectively. The urban expansion characteristics of Guizhou Province were prominent, and the reduction of cultivated land in Sichuan Province was the most obvious. Habitat quality index and water yield in the study area showed a decreasing trend, while three ecosystem services, including soil conservation, food production and carbon storage increased to some extent; (2) from the dynamic perspective, there was a significant tradeoff relationship between soil conservation and water yield, and a largely insignificant relationship between carbon storage and the other four ecosystem services, the area of soil conservation and water yield service tradeoff (61%) was larger than that of synergistic relationship (27%), and there was insignificant relationship between carbon storage and other four ecosystem services in a large area (> 70%); (3) from the static perspective, ecosystem services in different urbanization gradient areas showed significant heterogeneity. The non-urbanized area was similar to the study area as a whole, but the correlation between soil conservation and carbon storage gradually weakened. The tradeoff/synergic relationship between ecosystem services in rapid urbanization areas was the most significant. In particular, the correlation between carbon storage and habitat quality was the highest (R²=0.541). The interaction intensity between ecosystem services in past urbanization areas was weaker than those in other two areas, but any two ecosystem services all presented the positive correlation, among the 10 ecosystem service pairs, 7 ecosystem service pairs had significant positive correlation; and (4) the rapid expansion of construction land led to the decline of ecosystem services, especially the significantly negative impact on habitat quality. The interaction between ecosystem services in rapid urbanization areas was the most vigorous. The large increase in forest area led to an increase in soil conservation, especially in mountainous areas. Meanwhile, urbanization could cause a strongly synergistic decline in carbon storage and habitat quality. Although ecological protection and management projects can improve regional comprehensive ecosystem services, they will bring certain negative effects to territorial ecological restoration projects aimed at specifically increasing certain ecosystem services.