黔东南苗族侗族自治州生态系统健康的时空变化

黔东南苗族侗族自治州位于贵州东南部,是我国重点林区,也是长江、珠江上游地区的重要生态屏障区。以空间网格为基准单元,利用1990-2015年研究区的土地利用数据,结合社会经济、野外调查数据,基于"压力-状态-响应"模型、"活力-组织-弹性-功能"理论框架和空间分析模型,对黔东南州的生态系统健康时空变化进行分析,并选取城市化和地形位指数进行空间相关性分析,探讨影响黔东南州生态健康的关键因素。研究结果表明：时间分布上,1990-2015年期间,黔东南州生态系统健康指数呈现下降趋势,表现为从"亚健康"状态向"临界"状态的转变,呈现先增后减的波动式变化。研究期间生态系统健康水平的区域面积占比大小依次为亚健康（42%-45%）、临界健康（30%-35%）、健康（15%-22%）、不健康（0.1%-0.4%）、病态（<0.1%）,且25年间研究区生态系统各种健康水平的占地面积有显著变化。在空间分布上,黔东南州中部的台江县、剑河县和东北部的三穗县、锦屏县等地区生态系统健康水平较高,多处于亚健康和健康状态;而南部的榕江县、东部的黎平县和北部的镇远县、岑巩县等区域生态系统健康状况多处于临界状态;西北部的凯里市等区域生态系统健康水平最低,且整体上呈现下降的趋势。空间相关性研究表明：在1990-2015年期间,黔东南州的地形位指数与生态系统健康之间呈显著的空间正相关关系,"低-低"集聚区和"高-高"集聚区的面积均呈现"减-增-减"的波动趋势,而城市化与生态系统健康只在州府凯里市具有显著的空间负相关关系,说明在城市化水平较高的地方,人口密度、人均生产总值、建设用地比例等城市化因素是影响生态系统健康的主要原因,但在城市化进程较低的区域,生态系统健康受到地形梯度等自然因素的影响较大。本研究为黔东南州生态系统的管理与可持续发展提供理论基础。

Ecosystem health assessment of Qiandongnan Miao and Dong Autonomous Prefecture

The Qiandongnan Miao and Dong Autonomous Prefecture is located in the southeast of Guizhou Province. It is a crucial forest area in China and a significant ecological barrier area in the upper reaches of the Yangtze River and the Pearl River. Based on land use/land cover (LULC) data and socioeconomic and field survey data from 1990 to 2015, the study analyzes the spatiotemporal changes of ecosystem health (ESH) in Qiandongnan Prefecture by using the "Pressure-State-Response" model, "Vigor-Organization-Resilience-Services" theory frame and spatial analysis model. In this study, we selected urbanization and terrain index to detect the impacts of different factors on its ecosystem health. In terms of time distribution, ecosystem health index of Qiandangnan prefecture changed from a "sub-healthy" level to a "threshold" level from 1990 to 2015, with a slight increasing from 1990 to 2005 before plunging at 2005. The highest area in ecosystem health level occupied by "sub-healthy" (42%-45%), with the level of "critically healthy" accounting for 30%-35%, "healthy" 15%-22%, "unhealthy" 0.1%-0.4% and "sick"<0.1% in decrease order. In terms of spatial distribution, Taijiang County and Jianhe County, located in the center area, as well as Sansui County and Jinping County, located in the northeast, were at relatively health levels. The counties located in southern, eastern and northern regions were mostly in a "threshold" healthy state, such as Rongjiang County, Liping County, Zhenyuan County, and Cengong County. However, the lowest healthy area belonged to the northwest area like Kaili City, and its health index decreased from 1990 to 2015. Studies on spatial correlation showed that there was a significant positive spatial correlation between the terrain index and ecosystem health during the period of 1990-2015, and the areas, featured by "low-low" agglomeration and "high-high" agglomeration, presented a fluctuating trend of "decrease-increase-decrease". While there was a significant negative spatial correlation between urbanization and ecosystem health only in Kaili, capital of study area. And the results indicated that urbanization factors such as population density, per capita GDP, and the proportion of construction land were the main reasons affecting the ecosystem health in places with high levels of urbanization. However, the ecosystem health was greatly affected by natural factors in areas with a low urbanization process, for example, the terrain gradients. The research provides a theoretical basis for the management and the sustainable development strategy of the ecosystem of Qiandongnan Prefecture.