1993—2019年龙脊梯田植被覆盖度变化及其空间分布格局

Change of Vegetation Coverage and Its Spatial Distribution Pattern in Longji Terraced Field from 1993 to 2019

为了解区域植被覆盖度时空分布特征及其与地形的关系,促进生态环境建设健康发展。以龙脊梯田景区为研究区,基于1993、2006、2019年Landsat TM/OLI遥感影像及DEM地形数据,采用像元二分模型分析植被覆盖度空间分布及其对地形因子的响应特征。结果显示:(1)1993—2019年,龙脊梯田以林地、耕地为主要土地利用类型,植被覆盖度整体上呈增加趋势,多年平均植被覆盖度高达0.78;较高植被覆盖度(0.6~0.8)和高植被覆盖度(0.8~1.0)两等级占区域总面积比例为1993年87.77%、2006年88.96%、2019年87.94%,两等级均为低级别植被覆盖度的转移对象。(2)植被覆盖度随高程的升高而增大,随坡度的增大呈先增加后减小的趋势,在高程300~900 m和坡度0°~8°区域植被覆盖度最小,在高程>1500 m和坡度>25°区域植被覆盖度最大;植被覆盖度分布特征在各坡向上无明显差异,但北、东北、东方向的植被覆盖度较西北、东南方向高。1993—2019年龙脊梯田植被覆盖度分布主要受人类活动、海拔、坡度等因素的影响,人们通过种植植被扩大林地面积,提高了区域植被覆盖度,但人类活动范围逐渐向外拓展,低、较低植被覆盖度不断扩大。

Understanding the temporal and spatial distribution characteristics of vegetation coverage and their relationships with topography is the key to regional ecological construction and environment healthy development.Based on Landsat TM/OLI image data and DEM topographic data in 1993,2006 and 2019,this study analyzed the spatial distribution of vegetation coverage and its response characteristics to topographic factors with the method of pixel dichotomous model in Longji terrace.The results showed that:(1)From 1993 to 2019,woodland and cultivated land were the main land use types in Longji terraces,and the vegetation coverage showed an overall increasing trend,with the average value of 0.78 for many years.The total area ratios of relatively high vegetation coverage(0.6-0.8)and high vegetation coverage(0.8-1.0)were 87.77%,88.96%and 87.94%in 1993,2006 and 2019,respectively.Relatively high vegetation coverage area and high vegetation coverage area were the transferred object for low vegetation coverage area.(2)Vegetation coverage increases with elevation,but increases at first and then decreases with slope.Vegetation coverage was the lowest among all the areas in elevation of 300-900 m and slope of 0°-8°,while vegetation coverage was the highest in the alpine region with the elevation of>1500 m and the slope of 25°.There was no significant difference between the distributions of vegetation coverage in different slope aspects,but the vegetation coverage in the north,northeast and east directions was higher than that in the northwest and southeast directions.