【摘要】 以河西地区草地植被为研究对象,基于长时间序列的MODIS和野外实测数据,探讨了现有的3种植被覆盖度反演模型在研究区的适用性,并以此为基础分析了2001–2015年河西地区草地植被覆盖度时空分布特征。研究结果表明,基于TVI的经验模型能够在大范围内较好地估算植被覆盖度;河西地区草地生长季植被最大覆盖度空间分布差异明显,植被覆盖度由东南向西北逐渐降低;2001–2015年间研究区植被覆盖度总体上呈现出极显著增加的趋势(P <0.01),但在空间分布上存在一定的异质性;植被恢复的区域主要集中在中、西部地区;退化草地零星分布在马鬃山北部、石羊河流域西部以及祁连山东段地区。更多还原

【Abstract】 Taking grassland vegetation as the research object, we examined the applicability of three types of existing vegetation fractional coverage estimation method in arid areas based on long-time series MODIS and field measured data in the Hexi arid area. To this end, we analyzed the spatio-temporal dynamics of grassland vegetation fractional coverage in the test area from 2001 to 2015. The results indicated that an empirical model between the index TVI and vegetation fractional coverage had the highest precision, and is thus considered suitable for estimating the vegetation fractional coverage in the study area. The spatial distributions of the maximum vegetation coverage of grassland were significantly different, and the vegetation coverage decreased gradually from southeast to northwest. Overall, there was an extremely significant increase in vegetation coverage during the period from 2001 to 2015, albeit with spatial heterogeneity(P < 0.01). Restored areas were mainly concentrated in the central and western regions of the Hexi arid area, whereas degraded areas were scattered in the northern part of Mazong Mountain, the western region of the Shiyang River basin, and the east section of the Qilian Mountains.更多还原