中国新疆及中亚五国干旱区草地覆盖度反演与分析

干旱区的草地覆盖度较低,在光谱信息中表现较弱,增加了反演的难度。本研究在中国新疆及中亚五国干旱区对比4种植被覆盖度反演模型发现,像元二分模型能够较好地提取大范围内的植被覆盖度信息。在此基础上,反演2000―2013年中国新疆及中亚五国干旱区草地覆盖度并分析草地状况。研究发现,中国新疆及中亚五国草地覆盖度区域性差异较大,整体呈现退化趋势,退化区域主要分布在哈萨克斯坦的北部和西北部地区以及部分流域地区。不同等级草地覆盖度变化趋势为中等、中高和高植被覆盖度的草地有向低、中低植被覆盖度的草地转换。从国家及地区角度分析,哈萨克斯坦草地显著退化,而中国中国新疆的草地覆盖度均值在平稳中显著增长。

Retrieval and analysis of grassland coverage in arid Xinj iang,China and five countries of Central Asia

Because the low grassland coverage in the arid region causes the weak spectral information,grassland coverage retrieval becomes quite difficult.Comparing four remote sensing retrieval models,we found that the pixel dichotomy model can generally retrieve grassland coverage with higher accuracy.We further produced time-series (2000-2013)of grassland coverage based on the pixel dichotomy model and analyzed grassland conditions over Xinj iang and five countries of Central Asia.Results showed that grassland coverage showed large spatial heterogeneity in the study area.Grassland generally showed degradation trends,especially in the northern and western regions and some basins of Kazakhstan.Grasslands with medium,medium-high,and high grassland coverage were converted into the grasslands with low and medium-low grassland coverage. Grasslands in Kazakhstan degenerated significantly,while the average value of grassland coverage in Xinj iang was significant growth steady.