Understanding the effects of combined disturbances on eastern boreal forests using empirical and mathematical approaches

Abstract

Throughout eastern boreal forests, multiple anthropogenic and natural disturbances have influenced the forests’ ability to regenerate, with consequences for carbon storage, biodiversity and other ecosystem services. We examined responses of the boreal forest to the combination of gap forming disturbances (e.g., insect defoliation, forest fires) and moose herbivory through empirical (Chapter 2) and mathematical (Chapter 3) approaches. From our statistical models fit to field and remote sensed data, we found areas more likely to be gaps have lower carbon storage and are characterized by forests with shorter vegetation and higher seasonality in vegetation greenness. Furthermore, we provided evidence that moose may have impeded the recovery of up to 13 megatons of carbon storage across our study area, 20- 30 years after disturbances. Our mathematical model of an eastern boreal forest provides additional evidence moose herbivory can impede regeneration of boreal forests. However, aspects of plant growth can interact with moose herbivory to ultimately determine whether a gap regenerates to boreal forest or transitions to grassland. Our integration of statistical and mathematical approaches provides novel insights that may inform where forest gaps exist, why regeneration is important, and what needs to be done to restore mature boreal forest regeneration.