辽河保护区植被覆盖度时空动态变化及驱动因素

基于500 m分辨率MODIS NDVI数据和Landsat TM/OLI影像构建了辽河保护区2000—2018年的30 m植被覆盖度(fractional vegetation coverage,FVC)数据集,分析了辽河保护区划定前(2000—2009年)和划定后(2011—2018年)植被覆盖时空动态变化及其驱动因素。结果表明:2000—2018年,辽河保护区植被覆盖度整体呈微弱的增加趋势,2000—2009年植被覆盖度呈增加趋势,斜率为0.67%/a,而2011—2018年植被覆盖度呈波动下降趋势,斜率为-0.27%/a,植被覆盖度降低区域主要分布在地势较低洼的河道两侧;相对于2010年,辽河保护区植被在2012—2014年呈轻微的恢复趋势,但2015—2018年又出现了退化趋势。对比植被覆盖度的模拟值和实际值发现,2011—2018年人类活动对植被覆盖度的贡献率增至1.12%,其中2014年人类活动对植被恢复的作用明显。总体而言,辽河保护区划定以来,植被覆盖度呈先上升后下降趋势,主要是由于气候变化引起的;人类活动对植被恢复的作用为正向,植被恢复中人类活动贡献率高达8.42%。

Spatial-temporal dynamic change of fractional vegetation coverage and its driving factors in Liaohe Conservation Area

Based on the data of MODIS NDVI at 500-meter spatial resolution and the Landsat TM/OLI images, a 30-meter fractional vegetation coverage (FVC) data set of Liaohe Conservation Area was constructed, covering the time period 2000-2018. The study analyzed the spatial-temporal dynamics of FVC and its driving factors before and after the establishment of the Liaohe Conservation Area, during 2000 to 2009 and 2011 to 2018. The results showed that from 2000 to 2018, FVC of Liaohe Conservation Area showed a slightly upward overall trend, and that of the period between 2000 and 2009 witnessed an increasing trend with 0.67%/a, then declined with fluctuation during 2010-2018 with a negative slope -0.27%/a. A downward trend of FVC occurred at regional scale, the area of which mainly distributed on both sides of low-lying river reach. Comparing with the base year (2010), slightly restoration of vegetation in Liaohe Conservation Area presented during 2012-2014, also appeared the degradation trend from 2015 to 2018. By comparing the difference between the simulated FVC with the actual FVC in Liaohe Conservation Area, it was found that in the period of 2011-2018 the influence of human activities on FVC increased to 1.12%, and the restoration of vegetation in 2014 was significantly attributed to human activities. Overall, since the establishment of Liaohe Conservation Area, there was a tendency that FVC increased at first and then declined, which was attributed to the climate change. Furthermore, human activities had a positive effect on vegetation especially on vegetation restoration, the contribution of which was up to 8.42%.