1982—2016年东北黑土区植被NDVI动态及其对气候变化的响应

Changes in vegetation NDVI from 1982 to 2016 and its responses to climate change in the black-soil area of Northeast China

植被是陆地生态系统的重要组成部分,在调节气候、水土保持等方面具有重要作用,因此,监测植被生长变化并探讨其与气候变化之间的关系,在全球变化研究中具有重要意义。基于MODIS NDVI和GIMMS NDVI数据集,并通过一致性检验,在区域和像元两个空间尺度上,利用一元线性回归模型,研究东北黑土区1982—2016年植被生长动态,分析植被生长对气温和降水量的响应程度。结果表明:区域尺度上,1982—2016年东北黑土区植被生长季NDVI变化分为3个阶段(先增加继而减少最后再增加),区域植被的生长在气温、降水量的共同作用下,呈现出明显季节差异;像元尺度上,1982—2016年东北黑土区NDVI总体趋势为改善状态,主要改善植被类型为草原、森林和农业植被,鹤岗市、绥化市和长春市改善面积较大;多年平均NDVI值与同期气温和降水量具有一定的相关关系,平原地区植被NDVI与气温主要呈显著正相关关系,植被类型主要为耕地;平原地区边缘和山地地区的植被NDVI与降水量以显著正相关关系为主,主要植被类型为森林和草地。

As an important component of terrestrial ecosystems, vegetation plays an important role in climate regulation, soil and water conservation, and terrestrial carbon balance, The monitoring of vegetation growth and dynamics responsive to climate change therefore become quite necessary to understand global climate change. Based on the GIMMS NDVI and MODIS NDVI as well as a consistency check between these two datasets, this study examined the relationships between the spatiotemporal patterns of the NDVI and climate change over the black-soil area of the Northeast China from 1982 to 2016, using the unary linear regression model at both the pixel and regional scales. Our results showed that, at the regional scale, the NDVI during the growing season presented three different trends across these years （ i.e., firstly with an increase, then a decrease, and finally an increase）. Regionally, the vegetation growth was jointly affected by temperature and precipitation, which showed significant seasonal changes. By contrast, at the pixel scale, the NDVI exhibited a general increasing trend. The main vegetation types characterized by an increasing trend included grasslands, forests, and crops; and the cities that experienced significant vegetation growth are Hegang, Suihua, and Changchun. The mean NDVI had a close correlation with temperature and precipitation over the same period. Over the regions that are mainly covered by arable lands, the vegetation NDVI was positively related to air temperature, while it had a significant positive correlation with precipitation over the edges of the plains and mountains, where the dominant vegetation types are forests and grasslands.