西安市街区尺度绿色空间景观连接度 距离阈值的梯度分析

景观连接度距离阈值的选择直接决定着景观连通性的评价标准。若以鸟类、哺乳动物等物种的扩散能力作为景观连接度距离阈值的参照，通常会超出城市建成环境中小尺度绿色空间景观连通性评价的阈值范围。以西安市4种典型街区样方为研究对象，基于昆虫扩散能力，选取25、50、75、100、125、150、175、200m共8个距离阈值，采用整体连通性指数、可能连通性指数和斑块重要性指标，对研究区域内绿色空间景观连接度距离阈值进行分析和筛选。结果表明：1)不同研究与实践尺度下应选取适宜的指示物种，以其扩散能力作为景观连通性评价的参照，其中，城市街区尺度绿色空间景观连接度的相关研究宜选择昆虫作为指示物种；2)2020年西安市街区尺度城市绿色空间景观连接度的适宜距离阈值范围为50～150m，以125m为宜；3)西安市4种典型街区样方的绿色空间格局对景观连接度距离阈值的选择存在一定影响，景观连接度距离阈值的选择可依据城市绿色空间景观连通性的优化目标适当增减。

The Gradient Analysis of Distance Threshold of Green Space Landscape Connectivity at Block Scale in Xi'an

The choice of landscape connectivity distance thresholds directly determines the evaluation criteria of landscape connectivity. Using the dispersal ability of species such as birds and mammals as a reference for landscape connectivity distance thresholds is not sufficiently implemented in the evaluation of landscape connectivity of small-scale green spaces in urban built environment. Based on four typical block samples in Xi''an, eight distance thresholds, 25, 50, 75, 100, 125, 150, 175 and 200m, were selected based on insect dispersal ability, and the overall connectivity index, possible connectivity index and patch importance index were used to analyze and filter the distance thresholds of green space landscape connectivity in the study area. The result shows: 1) In different research and practice scales, the dispersal ability of suitable indicator species should be selected as the reference for landscape connectivity evaluation. In the research on landscape connectivity of green space in urban block scale, insects should be selected as the indicator species; 2) In 2020, the suitable distance threshold range of urban green space landscape connectivity in Xi''an block scale is 50-150m, especially 125m; 3) The green space pattern of four typical block quadrats in Xi''an has a certain impact on the selection of landscape connectivity distance threshold. The selection of landscape connectivity distance threshold can be appropriately increased or decreased due to the enforceability of urban green space landscape connectivity.