1998-2011年海河流域植被覆盖变化及气候因子驱动分析

Spatial-Temporal Change in Vegetation Cover and Climate Factor Drivers of Variation in the Haihe River Basin 1998-2011

基于1998-2011年的SPOT/NDVI数据,结合海河流域土地覆盖数据分析了海河流域植被覆盖的时空变化特征,然后利用海河流域30个气象站的气温和降水资料对海河流域植被覆盖变化的气候驱动力进行了分析。结果表明:1998-2011年海河流域NDVI呈缓慢上升趋势,植被覆盖状况总体上在改善,但是在空间存在明显差异,其中农田、森林、湿地改善最为明显,植被明显改善区域与植被高波动区分布基本一致,植被覆盖基本不变区域与植被低波动区基本一致;海河流域植被覆盖变化受气候因子驱动的面积比例为31.7%,非气候因子驱动型分布于整个流域,占整个流域面积的68.3%,其分布地区土地覆盖类型主要是农田、建设用地,表明人类活动对植被变化的影响较大。

Global warming has led to significant vegetation changes, especially in the past 20 years. The Haihe River Basin is an important agricultural and industrial region in China and under the influence of climate and human activities its ecological environment is changing. It is essential to conduct studies on spatial-temporal change in vegetation and drivers of variation based on remote sensing data. Here, we use remote sensing data for the SPOT Vegetation Normal Difference Vegetation Index （NDVI）, which reflects characteristics of plant growth. Combining land cover data and climate data, we analyze the change in vegetation cover and divers across the Haihe River Basin from 1998 to 2011. We found that vegetation cover improved slightly in the basin as a whole. Across all land cover types, farmland, wetland and forest improved more than others. The distribution of improved areas was consistent with high volatility areas. The distribution of basic invariant regions was consistent with low volatility areas. Most studies suggest that vegetation change is closely correlated with climate factors. So by correlation analysis we found that it is better correlated between NDVI and precipitation than temperature in most parts of the basin, suggesting that precipitation is the main factor responsible for vegetation change. According to partial correlation and multiple correlation analyses, drivers of change show that about 31.7% of the study area was impacted by climate factor drivers, while 68.3% was driven by non-climate factors. Therefore, it is clear that vegetation change is mainly affected by human activities.