山区植被覆盖度变化的地形分异特征——以贵州开阳县为例

植被覆盖度是生态恢复的重要指示器,研究其变化特征可为资源合理利用、生态恢复提供科学参考。以贵州省开阳县为研究区,基于landsat4-5 TM,Landsat8 OLI遥感影像,获取2002年、2019年30 m分辨率植被覆盖度数据,从阴坡与阳坡视角研究山区植被覆盖度变化和地形分异特征。结果表明:(1)2002—2019年阴坡与阳坡植被覆盖度总体呈南高北低分布,期间阴坡与阳坡植被总体处于恢复趋势。(2)研究时段内阴坡与阳坡植被覆盖度随海拔上升表现为增加趋势; 海拔小于600 m的地区阳坡和阴坡植被覆盖度差距最大; 2019年二者植被覆盖度在海拔小于600 m的地区下降明显,高于800 m的地区均有较大提升。(3)阴坡和阳坡植被覆盖度随坡度增加总体呈上升趋势,坡度大于35°后二者差异增强; 植被覆盖度增量随坡度增加总体表现为上升—下降特点。(4)阴坡和阳坡植被覆盖度随地形起伏度增加呈上升趋势。2002年阳坡各等级地形起伏度的植被覆盖度总体高于阴坡,2019年二者植被覆盖度差异性随地形起伏度上升而增强。综上,阴坡和阳坡植被覆盖度与海拔、坡度、地形起伏度呈正相关关系,二者在不同等级地形梯度上具有较大差异性。地形因子对山区阴坡、阳坡植被覆盖度的影响是多方面的,不仅从海拔和坡向上影响水热组合条件,也从坡度和地形起伏度上影响人类对山区林地资源的开发利用。

Topographic Differentiation of Vegetation Coverage Changes Between Shaded Slopes and Sunny Slopes in Mountainous Areas

Vegetation coverage is important indicator of ecological restoration. Studying change characteristics of vegetation coverage can provide scientific references for the rational use of resources and restoration of the ecological environment. Kaiyang County in Guizhou Province was chosen as an example. Based on landsat4-5 TM and Landsat8 OLI remote sensing images, the vegetation coverage data of 30 m resolution in 2002 and 2019 were obtained. From the perspectives of shaded and sunny slopes, the vegetation coverage changes and topographic differentiation characteristics were analyzed. The results showed that:(1)the vegetation coverage on the shaded and sunny slopes from 2002 to 2019 was generally high in the south and low in the north; during this period, the vegetation coverage on the shade and sunny slopes was generally recovering;(2)during the study period, the vegetation coverage on the shade and sunny slopes showed an increasing trend with the elevation; vegetation coverage difference between sunny and shady slopes was the largest in areas with an altitude of less than 600 m; in 2019, the vegetation coverage of the sunny and shady slopes decreased significantly in areas with an altitude of less than 600 m, and increased significantly in areas above 800 m;(3)the vegetation coverage of shaded and sunny slopes showed an overall upward trend with the increase of slope gradient, and the difference between the two increased when the slope was greater than 35°; the increase in vegetation coverage showed an upward-declining characteristic with the increase of slope gradient;(4)the vegetation coverage on the shade and sunny slopes showed an increasing trend with the increase of terrain undulations; in 2002, the vegetation coverage of sunny slopes at all levels of terrain undulations was generally higher than that of shaded slopes; in 2019, the difference in vegetation coverage between the two increased with the increase of terrain undulations. In summary, the vegetation coverage of shady and sunny slopes is positively correlated with altitude, slope, and terrain relief, and the two have great differences in different grades of terrain gradients. The influences of terrain factors on the vegetation coverage of shady and sunny slopes in mountainous areas are multi-facets. It not only affects the combination of water and heat conditions from altitude and slope, but also affects the development and utilization of forestland resources in mountainous areas from the slope and terrain relief.