喀斯特地区植被覆盖度变化及地形与人口效应研究

喀斯特山地流域植被变化具有独特性,探究其植被变化特征有利于石漠化治理和退耕还林工程科学实施。本文选取1990-2016年贵州石阡河流域Landsat系列遥感影像,采用像元二分模型和相关分析等方法研究流域植被覆盖度时空变化特征,并探究其变化的地形效应和人口效应。研究表明：① 1990-2016年贵州石阡河流域植被覆盖度总体处于上升趋势,植被恢复取得较好效果;② 1990-2016年贵州石阡河流域植被覆盖度变化的地形效应中,随海拔和坡度上升,植被覆盖度总体处于稳定上升趋势。随坡向变化中,无坡向地区植被覆盖度最低,其他坡向差异不明显;③ 1990-2016年贵州石阡河流域植被覆盖度变化的人口效应中,随人口密度上升,植被覆盖度总体处于下降趋势。研究结果可以为喀斯特地区退耕还林还草和石漠化治理提供科学依据。

Vegetation Coverage Change in a Karst Area and Effects of Terrain and Population

With increasing ecological protection awareness, vegetation restoration has received growing attention. Southwest China is one of the most concentrated areas of the world's karst. In the recent years, rock desertification control and vegetation protection has made good progress. In karst areas,exploring the characteristics of vegetation change is beneficial to the scientific implementation of rocky desertification control and recoverting farmland to forest. The article selected Landsat imagery, digital elevation model data, and population raster data of the Shiqian River Watershed in Guizhou Province, spanning from 1990 to 2016. The spatiotemporal variation characteristics of the watershed vegetation coverage were calculated by the remote sensing imagery; and we expored the topographic gradient characteristics and population impact characteristics of vegetation coverage change. We found that: (1) From 1990 to 2016, the vegetation coverage of the Shiqian River Watershed increased from 62.67% to 75.21%, and increased rapidly, especially after 2002. (2) With increases in the elevation and slope, the vegetation coverage generally rised steadily. With the change of slope direction, the coverage of flat vegetation became the lowest, while the difference of other slopes was not obvious. In 1990, the vegetation coverage in the flat area was 48.48%; while in 2016, the vegetation coverage in the flat area was 53.88%, but the vegetation coverage of other slopes was significantly higher than the flat land. (3) With the increase of population density, the vegetation coverage generally declinined. yet, when the population density was less than 50 people/km ² in 1990-2016, the vegetation coverage rised by less than 10%. When the population density reached 400 people/km ² in 1990-2016, the vegetation coverage increased by 20%. But overall, the higher the population density, the faster the vegetation will recover in the study area. The population density is currently greater than 450 people/km ², and the vegetation coverage is in a downward trend mainly due to urban construction. Our findings can provide guidance for the vegetation protection and reconverting farmland to forest projects in karst areas, and it is hoped that this study can provide reference for related research.