2000～2014年洞庭湖区植物面积变化及其与湖泊水位的关系

利用增强型植被指数(enhanced vegetation index,EVI),采用Mann-Kendall方法和Sen’s斜率估计方法,研究2000~2014年洞庭湖区的植物面积及其变化趋势,以及其与水位之间的关系。研究结果表明,枯水年洞庭湖区的植物面积最大,平水年的次之,丰水年的最小;2000~2014年期间,洞庭湖区增强型植被指数的变化存在空间异质性,东洞庭湖区的大部分区域的增强型植被指数无显著变化,南洞庭湖区的大部分区域的增强型植被指数显著增大;洞庭湖区18.08%的区域的增强型植被指数显著增大,这些区域主要集中在高滩地(平均海拔为26.61 m);7.51%的区域的增强型植被指数显著减小,这些区域主要集中在低滩地(平均海拔为25.79 m);随着湖泊水位的上升,洞庭湖区植物面积在减少,当洞庭湖水位为24 m时,最适合植物生长,当洞庭湖水位低于24 m时,洞庭湖区的植物面积受水位变化的影响较小。

Variation of Vegetation Area in Dongting Lake Area and Relationship between Vegetation Area and Water Level from 2000 to 2014

Based on the enhanced vegetation index and the trend testing method combining Mann-kendall method and Sen’s slope method, this paper studied the spatial distribution and variation trend of vegetation in Dongting Lake area from 2000 to 2014, and the relationship between vegetation area and water level. The results showed that the mean vegetation area in Dongting Lake area in the low water years was the largest,that in the normal flow year was in the middle, and that in the high flow year was the smallest. The variation trend of enhanced vegetation index in Dongting Lake area had spatial heterogeneity, there was no significant change of enhanced vegetation index almost over East Dongting Lake area, and the enhanced vegetation index increased significantly almost over South Dongting Lake area. The enhanced vegetation index increased significantly in 18.08% area of Dongting Lake area, mainly in the high beach area(the average elevation is 26.61 m);and the enhanced vegetation index decreased significantly in 7.51% area of Dongting Lake area,mainly in the low beach area(the average elevation is 25.79 m). With the rising of the water level, the vegetation area of Dongting Lake area decreased. When the water level of Dongting lake was lower than 24 m, the change of vegetation area in Dongting Lake area was less affected by the change of the water level.