The interannual change rate of the normalized vegetation index (NDVI) and its correlation with climate factors were compared under different permafrost degradation and vegetation types. The results indicated that NDVI of the coniferous forest accelerated, which was positively correlated with the temperature and negatively with the precipitation in the growing season. As the permafrost active layer deepens, the rate of increase in NDVI of coniferous forests gradually decreases from north to south. The grassland NDVI accelerated in non-permafrost regions, which was positively correlated with growing season precipitation. There is a clear difference between the response of mixed forests to climate in permafrost and non-permafrost regions. In permafrost regions, mixed forest NDVI is positively correlated with growing season temperature and negatively correlated with growing season precipitation. As the permafrost active layer deepens, the correlation coefficient between the NDVI of mixed forest and growing season temperature shifts from positive to negative, and the correlation coefficient with growing season precipitation shifts from negative to positive. This may be related to the different water supply caused by different active layer thickness. The results imply that under the coupling effects of climate and permafrost, climate warming will lead to gradual northward shifting of coniferous forests and mixed forests, and occupation by grasslands in non-permafrost regions.

基于归一化植被指数(NDVI), 分析多年不同冻土分布状态下植被生长的年际变化趋势及其与气候因子的相关性差异。结果表明: 1981—2014年, 中国东北多年冻土分布区针叶林的NDVI呈增加趋势, 与生长季温度正相关, 与生长季降水量负相关。随着冻土活动层深度增加, 针叶林NDVI的增加速度自北向南逐渐下降; 草原NDVI在非多年冻土区加速增长, 与生长季降水量正相关。混交林在多年冻土区与非多年冻土区对气候的响应出现明显的差异: 在多年冻土区, 混交林NDVI与生长季温度正相关, 与生长季降水量负相关; 随着冻土活动层加深, 与生长季温度从正相关变为负相关, 与生长季降水量由负相关变为正相关。原因可能与冻土活动层深度差异导致的不同水分供给条件有关。上述结果预示, 在气候–冻土耦合影响下, 未来气候变暖可能会促进针叶林和混交林逐渐北移, 草原可能会更多地占据非多年冻土区。