榆林地区生态系统弹性力评价分析

区域生态系统的弹性力研究是目前生态环境健康评价的重要指标,它反映了生态系统在偏离平衡状态后恢复到初始状态的自我调节和自我恢复的能力。以陕西省榆林市1区11县的生态系统各项指标现状为研究依据,综合运用了Fragstats和Arc GIS软件对榆林地区生态系统弹性力的各项参数进行计算,评价和分析了12个县(区)生态系统弹性力的时空演变与分布特征。结果表明:1995—2010年榆林地区生态系统弹性力呈平稳上升趋势,生态系统的自我调节能力和抗干扰能力不断增强。1995年榆林地区生态系统弹性力值低于0.4的地域面积所占比例为100%,截至2010年该数值降至41.45%,且主要集中在北部风沙草滩区。整体而言,榆林地区生态系统弹性力呈现南高北低的格局,大于0.6的区域主要集中在清涧、吴堡、绥德和米脂四县。研究揭示了榆林地区生态系统弹性力的发展变化趋势,以期为研究区的生态健康诊断与可持续发展决策提供参考。

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 ArcGIS 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 0 to 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 Yulin region, we found that the value was higher in the southern area than in the northern area. Each year, this gap between areas gradually increased. This study on the elastic strength coefficient and the elastic limit revealed the development and changing trends of ecosystem resilience in Yulin City, and provides a reference for the ecosystem health and sustainable development in the study area.