黑河生态调水后额济纳绿洲植被变化规律研究

Vegetation Changes of Ejina Oasis in the Lower Reaches of Heihe River Before and After Ecological Scheduling for Water Resources

为了客观认识和评估生态调水对黑河下游绿洲植被的影响,基于遥感技术手段,分析了生态调水后黑河下游额济纳绿洲植被变化规律。结果表明:1987-2017年,水域和林地、草地面积变化过程呈Ⅴ形,2000年以来林地、草地面积持续增加,植被覆盖度增加显著,植被覆盖改善区域占总面积的比例近30%,水域面积持续扩大;额济纳绿洲土地利用类型转换主要经历了由林地和中、高覆被草地转变为低覆被草地和未利用地,而后转变为林地和中、高覆被草地的过程;通过近20a的生态调水,总体上遏制了下游绿洲植被持续减少的状态,绿洲生态环境得到明显改善。说明黑河生态调水对下游植被恢复起到关键作用,随着生态调水年份的增加,林草地向高覆被转变趋势明显。

For understanding and evaluating the impact of ecological scheduling for water resources on vegetation in the lower reaches of Heihe River, vegetation change patterns in Ejina Oasis were analyzed based on remote sensing. The results show that the process of area variation of water, forest and grassland presents an obvious V-shape from 1987 to 2017. Since 2000, the areas of forest and grassland continuously in-crease. The vegetation coverage is significantly increased and the area of improved vegetation coverage is nearly 30% of the total area. Water areas continuously enlarge. The land use transformation of the Ejina oasis experiences the process of changing from forestland and high and medium coverage grassland to low coverage grassland and unutilized land, and then return to the previous environmental conditions in 1980s. After 20 years ecological scheduling for water resources, the vegetation loss tendency has been effectively controlled in the oasis. It demon-strates that the ecological water plays a crucial role in the process of vegetation recovering in Heihe River. The evolution of grassland and for-est to high coverage is very significant along with the years of ecological scheduling.