2001—2014年间黄土高原植被覆盖状态时空演变分析

Temporal and spatial variation analysis of vegetation cover in the Loess Plateau from 2001 to 2014

黄土高原植被覆盖状态的时空变化对于该地区植被恢复具有重要意义。基于2001—2014年间黄土高原地区MODIS-EVI2时序数据,建立2个反映植被覆盖状态的指标:植被覆盖强度与植被时间覆盖度。采用趋势分析以及突变点检测方法,得到近14 a间黄土高原植被覆盖状态的时空演变特征。研究结果表明:1黄土高原植被覆盖状态整体呈从西北到东南递增的分布特点,整个区域内近10 a间的植被覆盖状态增长速度相较于1982—2006年间明显增快;2研究区内多年植被覆盖强度与植被时间覆盖度呈正趋势变化的面积分别占整个研究区面积的43.04%和32.57%,发生变化的年份多集中于2006—2007年与2011—2012年;而多年植被覆盖强度与植被时间覆盖度呈负趋势变化的面积分别占整个研究区面积的2.92%与5.86%,发生变化区域多分布于农业种植区。研究有效证明了近年来退耕还林/防风固沙政策已取得了明显效果。

To explore the changes of time and space of the Loess Plateau vegetation status is of great significance for vegetation restoration in this region. Two indexes were established on the basis of the MODIS - EVI2 sequence data in the Loess Plateau region from 2001 to 2014 to reflect vegetation cover state from different sights. The first one is density of vegetation cover（ DVC）, and the second one is time of vegetation cover（TVC）. Then these two indexes were analyzed with trend analysis method and breakpoint analysis method. Finally the spatial and temporal evolution of vegetation cover in the Loess Plateau in the past 14 years was obtained. Some results have been obtained： （~） Vegetation cover in the Loess Plateau increased from northwest to southeast, and the vegetation cover in the whole region grew faster than from 1986 to 2006. （~）The rising trends of TVC and DVC areas were 43.04% and 32.57% of the whole study area, and the most prominent change happened during 2006 -2007 and 2011 -2012. The declining trends of TVC and DVC areas were 2.92% and 5.68% of the whole study area. The changed farming areas were mainly affected by the early stage of returning farmland to forest. The results show that the policy of returning farmland to forest and windbreak in recent years has made an obvious effect.