新疆阜康荒漠植被指数特征和时空过程分析

研究天山北坡典型荒漠区草地植被覆盖变化,对于荒漠区草畜平衡及畜牧业可持续发展具有重要现实意义。采用1990,1999和2008年同时相TM/ETM+遥感影像,经辐射校正和几何校正后,基于荒漠植被指数特征和垂直地带性特征,进行了专家知识决策树分类,研究了阜康市典型荒漠草地、农田等地物近20年间的归一化植被指数(NDVI)和面积变化特征。结果表明,1) 经辐射校正后的NDVI与实际地物情况更接近,大致呈高山草甸>农田>温性草甸>平原荒漠>山前荒漠的规律;2)近20年间农区面积大量占用平原荒漠草地和山前荒漠,新增农田面积296.3 km²,是1990年耕地总面积的1.54倍;3)高山冰盖消融随即转变成为高山草甸类型的趋势明显,20年间减少冰雪区74.7 km²,是1990年冰雪区总面积的0.345倍,这也印证了近20年来全球变暖的说法。

Vegetation index feature and spatial-temporal process analysis of desert grassland in the Fukang area of Xinjiang

Change of typical desert grassland in the northern Tianshan Mountains was analysed to give some constructive suggestions of sustainable development for both the environment and livestock. After the radiometric and geometric correction of TM/ETM+ remote sensing images in 1990, 1999, and 2008, the classification of land cover based on decision trees was implemented based on the vegetation index feature and vertical zone. The NDVI value calculated by radiometric corrected apparent reflectance was close to the actual surface features and generally showed the pattern: alpine meadow>farmland>temperate meadow>plain desert grass>piedmont desert grass. In the past 20 years, increasing farmland area occupied previous plain desert grassland and piedmont desert grassland to the extent that the new agricultural land area (296.3 km²) had become 1.54 times the total area of farmland in 1990. The trend of melting alpine ice transformed into alpine meadow became more apparent, and the reduced snow and ice area (74.7 km²) has reduced to 0.345 that in 1990.