不同格网尺度下的黄山市生境质量差异分析

生境质量格网尺度研究旨在甄别不同格网尺度生境质量评估结果差异,为范围大小不同的区域分析生境质量遴选适宜的空间尺度提供基础,以提高生境质量评估精度。本文以黄山市为例,基于地类斑块构建综合模型对2017年生境质量进行评估,并以30 m为基础尺度,通过尺度转换获得多个格网尺度综合生境质量值,采用弹性系数、空间自相关等方法定量分析格网尺度不同所导致的生境质量评估结果差异。研究结果表明：① 2017年黄山市本底生境质量值为2.02×10¹⁰元,平均值为21 126.1元/hm²,经过修正后的综合生境质量总值为1.84×10¹⁰元,平均值为18 627元/hm²; 随着格网边长增长,黄山市综合生境质量总值呈曲折式减少;② 土地利用分类的格网尺度效应显示,变化尺度为基础研究尺度的奇数倍时生境质量评估结果更精准;高程为0~200 m、200~400 m的区间带格网尺度效应较为明显;③ 以2个相邻的尺度计算生境质量变化弹性系数时,边长由150 m变为180 m、270 m变为300 m及900 m以上的相邻尺度值较高;以基础尺度为参照时,生境质量弹性系数随格网边长的增长呈幂函数式下降,格网边长由30 m变为60 m,生境质量变化最为敏感,由30 m变为210 m时,生境质量变化相对不敏感;④ 黄山市生境质量空间分布呈现显著正自相关,随着尺度格网边长增长,Moran's I指数呈波浪式减小,正态分布Z值呈幂函数式减小。

Effect of Grid Size on Habitat Quality Assessment: A Case Study of Huangshan City

Grid cell is the basic spatial unit to analyze the habitat quality based on remote sensing imagery. The choice of suitable grid size is very important for different regions, as the resolution must be fine enough to ensure the accuracy of habitat quality assessment. The purpose of this study is to identify differences in the habitat quality assessed at different grid scales, and to provide a basis for selecting appropriate spatial scales to analyze habitat quality in different regions, so as to improve the assessment accuracy. Taking Huangshan City as the example, this paper evaluated its comprehensive habitat quality in 2017 based on the model of ecosystem service value, habitat quality index consisting of NPP and NDVI, and InVEST habitat quality assessment model. With 30 m as the base scale and employing the elastic coefficient and spatial autocorrelation method, this paper assessed how changing grid sizes affect the habitat quality assessment results. The findings are as follows. (1) in 2017, the original assessment result of Huangshan's total habitat quality was 2.02×10¹⁰ yuan, with an average of 21126.1 yuan/hm². And the last adjusted total habitat quality was 1.84×10¹⁰ yuan, with an average of 18627 yuan/hm². (2) With the increase of pixel's side length, the total value of the comprehensive habitat quality assessment result decreased in the zigzag form. (3) The grid size effects on different land uses showed that the results of the habitat quality assessment were much more accurate when the scale of change was an odd multiple of the base scale, i.e., 30 m. And it was much clearer for the elevation range of 0~200 m and 200~400 m. (4) In terms of the elasticity coefficient of habitat quality calculated for scale change from one grid size to another, the coefficient was larger for the scale changes from 150m to 180 m, 270 m to 300 m and above 900 m. With the base scale as a reference, the elasticity coefficient of the habitat quality would decrease in the power-function form with increasing grid size. And the change of the habitat quality would be most sensitive when grid size changed from 30m to 60m. While the value of habitat quality change was relatively insensitive as the grid size changed from 30m to 210m. (5) The spatial distribution of habitat quality in Huangshan City showed a significant positive autocorrelation. With increasing grid size, the index of Moran's I decreased in a waving manner, and the Z value of the normal distribution also decreased in the power-function form. Our fidings can provide theoretical support for the selection of suitable grid sizes for habitat quality analysis in different places.