Evaluating the impacts of climate change on forest demography and carbon cycling in boreal forests

Boreal forests are currently experiencing rapid changes. CO₂ enriched conditions and warming with longer growing seasons are anticipated to increase boreal forests' growth and productivity, yet the frequency and severity of droughts and disturbances is also expected to increase in these forests. Increased growth and productivity under CO₂ enrichment may reduce the vulnerability of trees to extreme events such as drought. It, however, could also increase tree mortality through increased competition for light and soil resources, or through acceleration of tree lifecycle. The potential different responses of the dynamics of boreal forests to the predicted environmental changes lead to high uncertainty in the future contribution of boreal forests to the global carbon sink. We use data from long-term forest inventory and remote sensing together with earth system models to evaluate the trends in forest growth and productivity, carbon loss from tree mortality in boreal forests. A demographic population model and a dynamic vegetation model were applied to test the plausibility of several previously-posited mechanisms to explain the observed trends of growth, productivity, and mortality in boreal forests.