1988-2018年哈密绿洲植被覆盖度时空变化及其驱动力

目的] 对近30 a来哈密绿洲植被覆盖度时空变化及驱动力进行分析，为该地区绿洲持续健康发展提供理论借鉴。方法] 以1988，1998，2008及2018年4期影像为基础数据，利用像元二分模型计算了基于AFRI_SWIR2指数提取的植被覆盖度，利用动态度指数与植被覆盖度转移矩阵分析哈密绿洲植被覆盖度动态变化；再通过地理探测器对8个影响因子进行探测，探寻哈密绿洲植被覆盖度的驱动因子。结果] 近30 a来哈密绿洲面积从1988年的214 km²增长到2018年的632.1 km²，增幅达195%，但绿洲内植被覆盖度等级却较低，同时哈密绿洲面积主要扩展的区域在西北部和东南部区域；哈密绿洲的发展阶段可分为3个阶段：1988-1998年为低强度稳定期，1998-2008年为极度扩张期，2008-2018年为高强度稳定期。结论] 土地利用类型变化是造成哈密绿洲植被覆盖度变化的直接原因，同时在近30 a内，人为因素对哈密绿洲植被覆盖状况的影响远高于自然因素。

Spatial and Temporal Changes and Driving Forces of Vegetation Coverage in Hami Oasis During 1988-2018

Objective] The temporal and spatial changes and driving forces of vegetation coverage in Hami Oasis in the past 30 years were analyzed in order to provide theoretical reference for the sustainable and healthy development of oasis in this area.Methods] Based on the 4 images of 1988, 1998, 2008 and 2018, the vegetation coverage extracted from the AFRI_SWIR2 index was calculated using the pixel binary model. The vegetation coverage of Hami Oasis was analyzed using the dynamic index and the vegetation coverage transfer matrix. Then, 8 influencing factors were detected by the geographic detector, to explore the driving factors of the vegetation coverage of Hami Oasis.Results] In the past 30 years, the area of Hami Oasis increased from 214 km² in 1988 to 632.1 km² in 2018, with increase range of 195%. The development speed was relatively fast, but the level of vegetation coverage in the oasis was low. At the same time, the main expansion area was in the northwest and southeast regions. The development stage was defined as follows:1988-1998 was the low-strength stable period, 1998-2008 was the period of extreme expansion, and 2008-2018 was the high-strength stable period.Conclusion] The change of land use type is the direct cause of the change of vegetation coverage in Hami Oasis. At the same time, in the past 30 years, the influence of human factors on vegetation coverage of Hami Oasis is much higher than natural factors.