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Boreal Shield forest disturbance and recovery trends using Landsat time series

Frazier, Ryan J., Coops, Nicholas C., Wulder, Michael A.
Remote sensing of environment 2015 v.170 pp. 317-327
Landsat, climate change, forest management, forests, monitoring, reflectance, remote sensing, time series analysis, vegetation structure
Monitoring forest recovery following disturbance is important for both forest management as well as assessing possible climate change impacts on forest dynamics. To do so, an improved understanding of forest recovery processes and their relationship to remotely sensed spectral measures of recovery is required. Our objective in this research is to develop and apply a methodology for using Landsat time series to characterize forest recovery using spectral recovery trajectories. We focus our efforts in the Canadian Boreal Shield ecozone where a known geographic east to west distinction in disturbance regimes remains to be quantified. Results show that forest recovery following a stand replacing disturbance is detectable and quantifiable using a dense Landsat time series of spectral reflectance. All Tasseled Cap indices were found to capture an element of forest recovery following disturbance, with Wetness offering additional information on increasing vegetation structure and complexity. Tasseled Cap component trajectories of recovery show clear differences in both disturbance detection and forest recovery across the east and west Boreal Shield sections. The Cohen's d similarity metric indicated large differences (d>.08) in Wetness and Greenness-based spectral recovery trajectories when comparing the two Boreal Shield sections with the East Boreal Shield having markedly more above average recovery (+2 std. dev. from the mean) than the West. Based on our spectral recovery results, we also observe that forest recovery varies over the entire ecozone and is different between the east and west Boreal Shield forests.