宁夏不同生态功能区2000—2010年生态干旱特征及驱动分析

Ecological drought characteristics and analysis of driving factors of different ecological zones in Ningxia from 2000 to 2010

研究了不同生态功能区植被生态系统对干旱的响应。利用MODIS归一化植被指数和地表温度数据,构建温度植被干旱指数(temperature vegetation dryness index,TVDI),定量研究宁夏3个不同生态功能区2000—2010年的生态干旱特征,并分析其驱动因素。研究结果表明:近十年来,宁夏北部引黄灌区的生态干旱最弱,中部干旱带最强;生态干旱虽以波动为主,但同时存在一定的内在变化趋势,平均干旱强度在最近几年均有减弱的趋势。灰色关联度分析得出,中部干旱带驱动着宁夏全区的生态干旱状况,3个生态功能区的春旱均决定着其全年生态干旱状态,这一规律与宁夏植被生态格局有关。中部干旱带的生态干旱主要由单一降水因素所驱动,而北部引黄灌区与南部丘陵山区则是多因素复杂驱动,且普遍存在同季降水对生态干旱的影响大于上季降水的作用。本研究可为地方政府制定适宜的抗旱救灾行动提供科学依据。

The response of vegetation ecosystem to drought in different ecological zones in Ningxia is studied. Based on MODIS normalized difference vegetation index（ NDVI） and land surface temperature（ LST） data,the temperature vegetation dryness index（ TVDI）,which could measure the intensity of ecological drought,is constructed and used to study the quantitative drought characteristics in three different ecological zones of Ningxia Province from2000 to 2010. The driving factors of ecological drought are also analyzed. The results show that the intensity of ecological drought of the Yellow River irrigation area of northern Ningxia is weakest in recent 10 years. By contrast,the strongest ecological drought occurred in the arid zone of middle Ningxia. Ecological drought mainly fluctuated with a slight inherent trend and the average intensity of ecological drought in recent 10 years was weakening. The results of grey relational analysis（ GCA） indicate that the intensity of ecological drought of whole province is derived by the ecological drought of arid zone of middle Ningxia and the annual intensity of ecological drought of three ecological zones is driven by their spring drought respectively,and the law is related to the pattern of vegetation and ecology of Ningxia. The intensity of ecological drought of arid zone of middle Ningxia is driven singly by the precipitation,while the intensity of ecological drought of Yellow River irrigation area of northern Ningxia and mountains area of southern Ningxia is driven by complex factors. In general,the impact of precipitation on ecological drought inthe same season is more remarkable than in last season. The study could provide scientific evidence for the local government to make an appropriate action for disaster relief.