近30年山丹天然草原面积及盖度变化

Change Analysis of Grassland Area and Vegetation Coverage of Shandan Nearly 30 Years

本研究将3S技术与地面调查相结合,选择决策树分类和像元二分模型等方法,对山丹草原资源和草地植被盖度现状及变化进行了研究与评价。结果表明:研究区草原总面积39.59万hm^2,其中高寒草甸、山地草甸、温性草原、温性荒漠和温性草原化荒漠分别为8.47,3.14,9.61,8.23和10.14万hm^2;2014年研究区草原总面积比1987年减少了2.59万hm^2,山地草甸、温性草原、温性草原化荒漠和温性荒漠分别减少了8592.75,2377.08,3357.69和11559.75hm^2。各类型草地平均盖度依山地草甸、高寒草甸、温性草原、温性草原化荒漠和温性荒漠次序降低,分别为82.35%,57.60%,33.79%,17.07%和9.94%,正常年份分别以Ⅱ,Ⅰ,Ⅳ,V和V级草地盖度为主;从1987年到2014年,山地草甸盖度呈现逐年降低的趋势,高寒草甸呈先上升后下降趋势,温性草原、温性草原化荒漠和温性荒漠呈先下降后上升趋势。

Combining ＂3S＂ technology with ground survey in this research, we evaluated present situation and change analysis of grassland resource and vegetation coverage by decision tree classification and dimidiate pixel model. The results showed that the total grassland area of study area was 395900 hm^2 in 2014, which decreased 25900 hm^2 compared with the year 1987. The grassland area of alpine meadow, mountain meadow, temperate steppe, temperate desert and temperate steppe-desert were 84700, 31400, 96100, 82300 and 101400 hm^2, respectively. Mountain meadow, temperate steppe, temperate steppe-desert and temperate desert were decreased by 8592.75, 2377.08, 3357.69 and 11559.75 hm~. The average coverage of mountain meadow, alpine meadow, temperate steppe, temperate steppe-desert and temperate desert were 82.35%, 57.60%, 33.79%, 17.07% and 9.94% respectively. The vegetation coverage grades were II , I , IV, V and V mainly in normal years. The coverage of mountain meadow decreased year by year, and the alpine meadow increased firstly and then decreased, but the temperate steppe, temperate steppe- desert and temperate desert decreased firstly and then increased from 1987 to 2014.