基于植被覆盖度的广西平果县植被动态变化研究

Dynamic Changes of Vegetation Based on Vegetation Coverage in Pingguo County of Guangxi

以广西典型喀斯特地区平果县为研究区,采用1990年、2000年、2010年的Landsat系列图像,基于像元-线性分解模型,提取并分析了近20年广西平果县植被覆盖度的总体变化特征.结果表明:1990年、2000年、2010年研究区平均植被覆盖度分别为60.80%、59.54%、74.30%,呈现出平稳并缓慢上升的趋势.1990-2000年,低植被覆盖度呈现上升趋势(0%～20%范围内增加2.22%);中等植被覆盖度呈现上升趋势(20%～40%增加0.18%);高植被覆盖度呈现降低趋势(60%～80%范围内降低1.65%).2000-2010年,低植被覆盖度呈现降低趋势(0%～20%的范围内降低5.65%);中等植被覆盖度呈现下降趋势(20%～40%降低6.58%,40%～60%降低7.71%);高植被覆盖度呈现增加趋势(60%～80%范围内增加0.49%,80%～100%增加19.45%).其中平果县各个乡镇的植被均处于恢复期,而恢复期较好的乡镇主要分布在研究区的北部和东南部,对于植被覆盖度较好的乡镇,应采取关键保护措施.

The overall changing characteristics of vegetation coverage in Pingguo County,a typical Karst area of Guangxi,was analyzed based on the pixel-linear decomposition model and Landsat series images in 1990,2000 and 2010 in this paper.The results indicated that the average vegetation coverage in the study area were 60.80%59.54%and 74.30%in 1990,2000 and 2010 respectively,showing a kind of steadily and slowly increasing trend.From 1990 to 2000,the low vegetation coverage increased by 2.22%in the range of 0%~20%,the medium vegetation coverage increased by 0.18%in the range of 20%~40%,and the high vegetation coverage decreased by 1.65%in the range of 60%~80%.From 2000 to 2010,the low vegetation coverage showed a decreasing trend(5.65%in the range of 0%~20%),the medium vegetation coverage showed a decreasing trend(6.58%in the range of 20%~40%,7.71%in the range of 40%~60%)and the high vegetation coverage showed an increasing trend(0.49%in the range of 60%~80%,19.45%in the range of 80%~100%).The vegetation coverage of every township in Pingguo County is in the recovery period,and the towns with better vegetation coverage mainly distribute in the north and southeast of the study area.