Evaluation of ecosystem resilience in Yulin, China

Ecosystem resilience is one of the hot topics in regional ecosystem health assessments. As an important indicator,it has attracted widespread attention. Ecosystem resilience refers to the self-regulation capacity of an ecosystem to restore itself to its initial state after deviation from the equilibrium state. The elastic strength coefficient and the elastic limit are two main components of ecosystem resilience,representing the level of the elastic force and elastic range,respectively. Based on the ecosystem indicators( such as landscape diversity index,vegetation Index,precipitation variability,temperature variability,flexible scores,the percentage of land use types) of Yulin City( Shanxi Province,China),Fragstats and Arc GIS software were applied to calculate the various parameters of the ecosystem resilience system in Yulin,including evaluating and analyzing the spatial and temporal characteristics of ecosystem resilience in twelve counties( districts) of the Yulin region. The results indicated that from 1995 to 2010,there was a steady upward trend in ecosystem resilience in the Yulin region. The self-regulation and self-healing ability of ecosystems had strengthened over time. From 2000 to 2005,ecosystem resilience increased rapidly,but the growth rate of resilience slowed after 2005. To facilitate the ecosystem resilience variation study,resilience,in accordance with its value range,was divided into four grades: level 1( range of 0to 0. 2),level 2(0. 2 to 0. 4),level 3( 0. 4 to 0. 6),and level 4( 0. 6 to 0. 8). In 1995,100% of the area had ecosystem resilience less than 0. 4( level 2 or lower),but it dropped to 41. 45% in 2010( mainly concentrated in the wind sandy and grass shoal areas of northern Yulin). For the different counties,after 2000,there was an increase in the area with ecosystem resilience levels greater than 0. 4( level 3 and higher). Before 2000,in the Jiaxian,Zizhou,Mizhi,Suide,Wubu,and Qingjian counties in southern Yulin,92. 2%,92. 6%,87. 1%,84. 9%,83. 5%,and 79. 7% of the total area had ecosystem resilience values greater than 0. 4,respectively. In contrast,none of the remaining counties( except for Fugu County in northern Yulin) exceeded an area of 60% for the same value. In addition,areas with ecosystem resilience levels higher than 0. 6( level 4),were mainly concentrated in the southern region of Yulin( e. g.,Qingjian,Wubu,Mizhi,and Suide counties). Therefore,when the value of ecosystem resilience maintained steady growth in the Y