东北多年冻土区植被NDVI变化及其对气候变化和土地覆被变化的响应

利用1982~2006年的NOAA AVHRR-GIMMS和MODIS 2种数据集的归一化植被指数(NDVI)数据对东北多年冻土区植被NDVI年际动态和空间差异进行分析,并结合气象数据和土地利用/覆被数据分析了植被NDVI对气候变化和土地利用/覆被变化的响应.研究表明,东北多年冻土区植被NDVI值较高,且空间差异明显;森林为该区主要植被类型,NDVI值较高,主要分布于大小兴安岭和伊春地区;草地集中分布于西南部, NDVI值相对较低.东北多年冻土区过去25a间植被生长的变化趋势为:伴随着气温的显著升高和降水量减少,植被NDVI显著下降.较气温而言,降水量是影响植被NDVI的主要因子(r = 0.77, P < 0.01).在气候变化和人类活动的双重作用下,东北多年冻土区植被NDVI在1982~2006年间表现为4个阶段:1982~1990年,植被NDVI虽有小幅波动,但整体上呈持续增加的趋势;1990~1993年,植被NDVI呈迅速下降趋势; 1993~1997年,植被NDVI呈现回升态势,表现出缓慢上升的趋势;1998~2006年,植被NDVI呈现总体下降趋势.不同植被类型表现出不同的NDVI年际变化规律,尤以草地NDVI值波动最大.植被NDVI变化空间异质性显著.气候变化和多年冻土退化影响了东北多年冻土区植被NDVI动态.年均气温升高和年降水量降低影响了植被的生长.从像元尺度来看,研究区植被NDVI与气温和降水均具有较显著的相关性.研究区土地利用/覆被变化的分析结果表明,不同的土地利用类型间的转变对植被NDVI的大小和空间分布产生了重要影响.

The vegetation NDVI variation and its responses to climate change and LUCC from 1982 to 2006 year in northeast permafrost region

Based on the remote sensing data, GIMMS AVHRR and MODIS datasets NDVI during 1982~2006, the annual dynamic and spatial variability of vegetation NDVI in northeast permafrost region were studied. And combined the meteorological data and land use/cover data the responses of vegetation NDVI to climate change and land use/cover change was analyzed. The vegetation NDVI in northeast permafrost was high and had obvious spatial variability. Forest was the principal vegetation type which NDVI was the supreme and mainly distributed in the zone of Da\Xiao Hinggan Mountains and Yi-Chun. The NDVI of lawn which mainly distribute in the southwest was relatively small. The variation trend of vegetation growth in the 25 years in northeast permafrost region was that vegetation NDVI decreased prominently with the temperature rose significantly and precipitation decreased. Precipitation was the main factor influenced vegetation NDVI compared with temperature (the correlation coefficient is 0.74). The northeast permafrost region vegetation NDVI showed four stages by the influences of climate change and human activities from 1982 to 2006. The different vegetation types showed different annual variation disciplines. The discipline of lawn had the biggest volatility in the 25 years. The change of vegetation NDVI had obvious spatial variability. The climate change and permafrost degradation influenced the vegetation NDVI dynamic in the northeast permafrost region. The risen annual mean temperature and decreased annual precipitation had affected the growth of vegetation. In the scale of pixel, the vegetation NDVI had significant correlation between and temperature as well as precipitation and showed temporal and spatial response to the changing climate. The analysis result of LUCC stated clearly that the changes of land cover type in different areas had leaded to increased or decreased NDVI value. Although the LUCC proportion in northeast permafrost region was small, different transformation between the land cover types caused important influence to the size of NDVI value and spatial distribution.