植被覆盖度的时空格局及其影响因素分析

王守梅 刘雨先 龚熊波 杨波

摘 要：以万源市为研究区，基于Landsat影像，运用一元线性回归和三维景观指数分析1996—2019年该区植被覆盖度时空格局，并采用地形差异修正指数和叠置分析探讨影响植被覆盖度产生变化的自然因素和人为因素。结果表明：（1）万源市植被覆盖度整体较高，年际变化趋势上植被覆盖度的增加区域明显大于减少区域。（2）景观格局总体呈现多样性指数下降、聚散性指数上升、景观异质性降低、各植被类型连接性增强等特征。（3）植被覆盖度受地形影响明显，与高程、坡度呈正相关。在高程<400m、坡度<8°区域植被减少呈优势分布，在高程1000～1200m、坡度25°～35°区域植被增加类型呈优势分布。（4）万源市植被覆盖增加主要由耕地、草地转为林地引起，建设用地占用是导致植被覆盖度降低的重要因素。

关键词：植被覆盖度;三维景观格局;地形因子;土地利用;万源市

中图分类号 Q948;TP79文献标识码 A文章编号 1007-7731（2021）05-0132-08

Abstract： Taking Wanyuan City as the research area， based on Landsat data， methods such as linear regression slope， and three-dimensional landscape index were used to analyze the temporal and spatial changes of vegetation coverage in the study area from 1996 to 2019. The terrain difference correction index and overlay analysis method was used to explore the impact of terrain factors and land use changes on vegetation coverage. The results showed that： （1） The vegetation coverage of Wanyuan City is generally relatively high. In terms of the inter-annual change trend， the spatial increase area of vegetation coverage is significantly larger than the decrease area. （2） The overall change of landscape pattern shows a decline in diversity index， an increase in aggregation index， and a different landscape. Quality is reduced， and the connectivity of vegetation types is enhanced. （3） The vegetation coverage is obviously affected by the terrain， and is positively correlated with elevation and slope. When the elevation is less than 400m and the slope is less than 8°， the vegetation reduction is predominantly distributed. When the elevation is between 1000m and 1200m and the slope is less than between 25°and 35°， the vegetation increase types is predominantly distributed. （4） The increase in vegetation coverage in Wanyuan City is mainly caused by the conversion of cultivated land to woodland and grassland. The occupation of construction land is an important factor in the decrease in vegetation coverage.

Key words： Vegetation coverage; Three-dimensional landscape pattern; Topographic factor; Land use; Wanyuan City

植被覆蓋度是指植被冠层在地面上的垂直投影面积与土地总面积的百分比[1]，是反映生态环境状况的重要参数。植被覆盖变化监测以及生态环境变化与人类可持续发展的关系已成为学术研究热点。目前，国内外学者针对不同城市[2-4]、流域[5， 6]、地貌[7-9]、矿区[10，11]、植被类型区[12，13]的植被覆盖度时空变化特征及其影响因素开展了大量研究。在时空变化特征方面，常用的方法主要有图像差值法[14，15]、趋势分析方法[10]、稳定性评价[16]、Mann-Kendall非参数检验[3， 17]、景观格局分析[18-22]等。景观格局分析是景观生态学的主要分析方法，目前越来越多的学者将其应用于植被覆盖度的研究中，如王新闯[18]、苏艳琴[19]、裴志方[20]、王静[21]、高彦俊[22]等分别以河南省、福建省沙县、宁夏市、京津冀地区、白龙江流域为研究区，进行了植被覆盖度景观格局分析。……