Prevalence of multiple forest disturbances and impact on vegetation regrowth from interannual Landsat time series (1985–2015)

Abstract

Given long time series of satellite imagery, multiple disturbances can be detected for a particular location at different points in time. We assessed multiple disturbances for the 650 Mha of Canada's forested ecosystems using annual change information derived from Landsat time series imagery (1985–2015). Changes were typed by agent (fire, harvest, and non-stand replacing). Spectral change rate and time between successive disturbances were used to characterize disturbance-type combination differences. Short-term spectral recovery following the last disturbance was compared to a reference sample of pixels disturbed only once. Results indicated that of the 97.6 Mha disturbed, 13.5 Mha have had two or more disturbances, with low magnitude non-stand replacing disturbances involved in the majority of occurrences (77.2%). The total area disturbed represents 18.27% of forest ecosystems, with 2.53% having multiple disturbances and 0.54% having multiple stand-replacing disturbances. Systematic time series-based investigation of multiple disturbance events and agents provides insights on forest disturbance dynamics and recovery processes.