摘要:
新疆哈密大南湖地区为我国典型的干旱—半干旱地区中的荒漠区,研究该地区天然植被近年来在全球气候变化背景下的发育状况具有重要意义.为此,使用Landsat遥感数据、数字高程模型及当地气象数据,采用像元二分模型提取植被覆盖度;通过相关分析,研究该地区1992—2014年间天然植被的时空变化特点.结果表明,23 a来该区植被覆盖度有增加的趋势;植被覆盖度整体上与地形高度呈弱正相关,局部植被密集处往往是地形相对低凹的盐渍土区及干河谷,而戈壁滩中植物稀少;植被覆盖度与当地日照百分率及潜在蒸散量呈正相关,而与降雨和湿润指数不相关.研究表明,研究区植被生长可能主要与地下水相关,1992―2014年间全球气温升高导致附近冰川消融加快,在一定程度上促进而不是阻滞了天然植被发育.
Abstract:
The Dananhu district in Hami of Xinjiang is a typical gobi desert in Northwest China. In this paper,the authors investigated the temporal-spatial variations of the natural vegetation coverage during 1992―2014 in this region,using correlation analyses and dimidiate pixel model based on the multi-spectral remote sensing data,the local meteorological data,and the digital elevation model. The results show that, from 1992 to 2014, vegetation coverage in the region showed a trend of increase. Generally the vegetation coverage is weakly positively correlated to elevation;locally,however,the plants(mainly juniper tamarisk,haloxylon ammodendron,and reed) are more developed in the relatively depressed localities (saline areas or sandy dry riverbeds) than those in Gobi desert areas. The vegetation coverage is positively correlated to the sunshine duration and evaporation, but unrelated to precipitation and humidity. It is suggested that the natural plants in this regions live on groundwater mainly. The global temperature increasing during 1992 -2014 might to some extent promote, instead of retard, the natural vegetation,probably through enhancing the groundwater supply due to glacier melting at nearby mountains.
下载: