重建NDVI时间序列及火后森林恢复时空动态分析

Post-Fire Forest Recovery Assessment Based on NDVI Time Series

对大兴安岭图强1987年火后森林NDVI连续长时间动态恢复轨迹及其趋势特征的空间分布进行研究,探究森林时空动态恢复状况,为空间尺度、长时间序列森林火后动态恢复监测提供参考.以归一化植被指数(NDVI)作为火后森林动态恢复的表征参量,基于季节校正方法,重建生长旺季NDVI时间序列;结合火烧强度数据,监测不同火烧区森林NDVI恢复轨迹;利用Mann-Kendall趋势分析法,分析火后12年森林NDVI变化趋势的空间分布.结果表明:季节校正后NDVI年际间可对比,各火烧强度下NDVI年际变化规律明显.火后12年是森林的主要恢复期,火烧区森林总体恢复较好.森林NDVI时空动态恢复趋势与火烧强度存在一定相关性,重度过火区NDVI上升趋势最显著.火后不同的森林恢复措施进一步导致火烧区内部NDVI趋势的空间差异.

The spatial distribution of forest recovery trend and its recovery trajectory in 1987-2015 following the 1987 fire in the Greater Hinggan Mountains was explored,providing reference for monitoring the dynamic recovery process of post-fire forests at time and spatial scales. Regard the normalized difference vegetation index（ NDVI） as an important characterization parameter of post-fire forest recovery,a time series of NDVI in growing season were reconstructed via seasonal adjustment. The inter-annual NDVI variation curves in areas with different fire intensities were exacted to monitor NDVI recovery process.Spatial distribution of NDVI trends in forest area during 1988-1999 were analyzed by the Mann-Kendall trend analysis method. The results showed that NDVI time series were consistent in 28 years after fire and there was no significant inter-annual fluctuation along the NDVI curves after seasonal correction. The NDVI-based recovery was correlated with fire intensity. Forests recovered remarkably in heavy fire zone.Different forest restoration operations after fire led to the spatial difference of the NDVI trend within the heavy fire zone.