榆中县生境质量和生境退化的时空分异特征及其地形梯度效应

Spatio-temporal patterns of habitat quality and habitat degradation and its terrain gradient effects of Yuzhong County based on InVEST model

【目的】生境质量是反映生态系统服务水平的重要指标,在新时期国土空间规划编制及生态文明建设的双重背景下,加强对重点县域生境质量和生境退化度的评估,可以为区域的生态保护提供参考。【方法】本研究以榆中县为例,基于DEM数据与土地利用栅格数据,应用InVEST模型、图谱分析以及地形位梯度等方法对榆中县的生境质量、生境退化度及其地形梯度效应进行分析。【结果】研究期间榆中县生境质量、生境退化度未发生变化的图谱单元占比大于发生变化的图谱单元占比,说明榆中县生境质量和生境退化均发生小幅度变化,平均生境质量从2008年的0.2289变为2018年的0.2266,说明榆中县生境质量存在下降趋势;平均生境退化度从2008年的0.007370上升为2018年的0.007389,表明榆中县生境退化程度有小幅度增加的趋势。生境质量始终保持由西南向东北递减的空间分布格局,以宛川河为界,生境退化呈现宛川河以北低而以南高的分布特点。榆中县生境质量及生境退化分布指数具有明显的地形位梯度变化效应,二者的优势地形位梯度差异较大,高质量生境在第4、5等地形位梯度上分布最多,这与林地、草地的分布具有一致性,生境退化度高值在1等地形位梯度上,这与耕地、园地、水域、建设用地的分布具有一致性。【结论】榆中县生境质量和生境退化度与地形位之间具有明显的关联,地形位指数较低的区域是生境变化的主要区域。

【Objective】Habitat quality is an important representation of regional ecosystem services.Under the background of territorial spatial planning and ecological civilization construction,it is of great significance to strengthen the research on habitat quality for regional ecological protection.【Method】Taking Yuzhong County as an example,this paper analyzed the habitat quality,habitat degradation degree and topographic gradient effect in Yuzhong County based on DEM data and two phases of land use grid data,using InVEST model,atlas analysis and topographic gradient method.【Result】During the study period,the proportions of map units with no changes in habitat quality and habitat degradation were larger than those with changes,indicating that both habitat quality and habitat degradation had small changes in Yuzhong County.The average habitat quality in Yuzhong County changed from 0.2289 in 2008 to 0.2266 in 2018,indicating a downward trend.The average habitat degradation degree increased from 0.007370 in 2008 to 0.007389 in 2018,indicating that the degree of habitat degradation in Yuzhong County had a slight increasing trend.Habitat quality has always maintained a spatial distribution pattern decreasing from Southwest to Northeast.With Wanchuan River as the boundary,the habitat degradation presents a distribution characteristic of lower Wanchuan River in the North and higher in the South.The habitat quality and habitat degradation distribution index in Yuzhong County have obvious topographical position gradient effects.The dominant topographical position gradients of the two are quite different.The high-quality habitats are most distributed on the 4th and 5th grades of topographical position gradients,which are the same as forest land.The distribution of grassland is consistent,and the high value of habitat degradation is on the topographical level gradient of 1st level,which is consistent with the distribution of cultivated land,garden plots,water areas and construction land.【Conclusion】There was a significant correlation between habitat quality and habitat degradation degree and terrain in Yuzhong County,and the area with lower terrain index was the main area of habitat change.