Understanding variations in the post-fire recovery of North American Boreal forests

Fire disturbance is a key component in North American boreal forests' (NAB) dynamics. The rate and severity of fire in NAB have increased and is projected to continue its upward trend in the 21st century as a consequence of climate change. This fire regime shift inevitably alters the structural and functional states of NAB, thus, understanding how NAB have responded to historical fire disturbance is crucial for both diagnostic and prognostic assessments of NAB. Remote sensing based approaches have quantified and tracked the following recovery process of NAB, however, it is still poorly understood how the satellite-observed patterns vary over different abiotic and biotic gradients. Here, we hypothesize that successional processes during recovery from disturbance in conjunct with environmental condition affect the relation between canopy structure and functioning, in turn, variations in the satellite-observed post-fire recovery.

Our approach first exploits the MODIS derived leaf area index (LAI) and historical fire records to characterize spatial patterns of changes in NAB. Then we synergistically combine the mechanistic model and additional remote sensing data including lidar altimetry and spectrometry to understand observed patterns in the MODIS LAI. In this work, we use the Allometric Scaling and Resource Limitation (ASRL) model that encodes principles of metabolic scaling, structural stability, allometry and constraints from resource limitations to determine the functional state of NAB. The lidar and spectrometry serve to characterize the structural and compositional states of NAB. Our study quantifies the legacy effect of fire disturbance in the relation between canopy structure and functioning of NAB.