COS 131-4 - Limited increase in post-disturbance forest regrowth rates with projected climate changes in eastern American boreal forests

Background/Question/Methods

The regeneration of severely disturbed forests is undoubtedly among the most powerful drivers of current and future forest dynamics. However, many uncertainties regarding the regrowth and early successional dynamics of these recently disturbed forests remain in the context of changing climate. This study investigates the effects of climate, forest composition, and other landscape-scale environmental variables upon boreal forest regrowth following clearcutting in eastern Canada. Our main objective was to develop a model that could predict the effects of future climate changes upon post-logging forest height growth at high spatial resolution and over a large area. We used a promising recently developed modeling method based on time-since-harvest and airborne laser scanning data. In brief, we modeled forest height measured with LiDAR in 20m resolution virtual plots as a function of time elapsed since the last clearcut and several climatic, forest composition, and other environmental variables (e.g., topography and soil hydrology). Once trained and validated with ≈240K virtual plots, the model was used to predict potential post-logging forest regrowth at 20m resolution across a 240 000 km² area following different scenarios that depict a range of projected changes in temperature and moisture across the study area for the 2041-2070 period.

Results/Conclusions

Our results predict an overall beneficial but limited effect of projected climate change upon forest regrowth rates in our study area, with changes mostly comprised between -5% and +40%. Although beneficial effects are pervasive across our study area, they are more pronounced for conifers forests and northern, cold, and slow-growing forests. To our knowledge, this is the first study that has specifically addressed the effects of climate changes upon boreal forest height regrowth after stand-replacing disturbance. These results provide new knowledge and insights into the impact of future climate change on boreal forests necessary for sustainable forest management.