长三角2000-2018年陆地生态系统完整性动态变化与驱动因素

生态系统完整性是维持生态服务功能和生态系统稳定的重要因素,已成为生态系统管理的目标和衡量生态系统价值的重要指标。我国尚未形成统一的陆地生态系统完整性评估体系和综合指数,基于耗散结构理论从生态系统结构、功能和弹性三方面遴选5个一级指标和6个二级指标,构建了一套适用于景观尺度,易于量化评估、动态监测的陆地生态系统完整性指标体系(terrestrial ecosystem integrity index,TEII);并以长三角区域为例,分析了2000-2018年陆地生态系统完整性动态变化及驱动力因素,结果表明:(1)长三角TEII均值整体呈下降趋势,19%的面积显著降低,15%的面积显著增加;(2) TEII显著降低区域呈两带两圈多点分布格局,显著增加区域主要分布在长三角西北部,在空间上聚集分布;(3)耕地转建设用地、草地转建设用地、林地转耕地和林地转建设用地为TEII下降的主要驱动力之一;(4) TEII与GDP呈显著负相关,人口总数与完整性在2000-2005年无显著相关性,2010-2018年呈显著负相关,且负相关紧密程度不断增加,说明长三角区域经济发展和人口增长对完整性形成了日趋严重的胁迫。

Changes of terrestrial ecosystem integrity index and driving factors in the Yangtze River Delta from 2000 to 2018

Ecosystem integrity plays an important role to maintain ecosystem services and ecosystem stability. With the increasing attentions on comprehensive ecosystem management, ecosystem integrity has become the goal of ecosystem management and an important index to measure the value of ecosystem. However, there has not been a unified assessment system and comprehensive index of terrestrial ecosystem integrity in China. Therefore, a framework of terrestrial ecosystem integrity index (TEII) was established in this paper, based on the theory of dissipation structure at the landscape scale, which is easy to quantify and dynamically monitor. The framework selects five primary indicators and six secondary indicators from three aspects, including ecosystem structure, ecosystem function, and ecosystem resilience. Among them, ecosystem structure focuses on landscape heterogeneity, ecosystem function focuses on the internal ecological physical process of energy flow, material cycle and water balance, and ecosystem resilience focuses on the ability to resist external disturbance and recover after disturbance. Taking the Yangtze River Delta as a case study, the remote evaluation method and geographic information system (GIS) technology were used to evaluate the dynamic change trend of terrestrial ecosystem integrity in the Yangtze River Delta from 2000 to 2018. In addition, Pearson correlation analysis was used to analyze the impact of land use change, economic development and population growth on TEII. The results show that: (1) the mean value of TEII in the Yangtze River Delta presented a downward trend, with a significant decrease in 19% and a significant increase in 15% of total area, respectively. (2) The area with significantly reducing trend of TEII presented a two-belt, two-circle and multiple points distribution pattern. The two-belts are distributed in the coastal development belt and the development belt along the Yangtze River, the two-circles are distributed in the metropolis circle of Suzhou,Wuxi,Changzhou and Hangzhou,and the multiple points distribution in many cities around the main urban areas, such as Hefei, Xuzhou, etc. While the area with significantly increasing trend was mainly distributed in the northwest of the Yangtze River Delta. (3) Land use change (farmland to construction land, grassland to construction land, forestland to farmland and forestland to construction land) is one of the main driving forces of the TEII decline. (4) The TEII has a significantly negative correlation with GDP. Population has no significant correlation with TEII from 2000 to 2005, but has a significantly negative correlation from 2010 to 2018. It implied that the degree of correlation was increasing and current economic development and population growth have posed a threat to ecosystem integrity. The paper aims to provide scientific basis and methods for the evaluation of ecosystem integrity and the optimization of ecological protection space (ecological conservation red line, nature reserve and national park, etc.) in the Yangtze River Delta.