Fire severity mediates climate-driven shifts in understorey community composition of black spruce stands of interior Alaska

Abstract

Question: How do pre-fire conditions (community composition and environmental characteristics) and climate-driven disturbance characteristics (fire severity) affect post-fire community composition in black spruce stands? Location: Northern boreal forest, interior Alaska. Methods: We compared plant community composition and environmental stand characteristics in 14 black spruce stands before and after multiple, naturally occurring wildfires. We used a combination of vegetation table sorting, univariate and multivariate statistics to determine the impact of fire severity and site moisture on community composition, dominant species and growth forms. Conclusions: In the rapidly warming climate of interior Alaska, changes in fire severity had more effect on post-fire community composition than did environmental factors (moisture and pH) that govern landscape patterns of unburned vegetation. This suggests that climate change effects on future community composition of black spruce forests may be mediated more strongly by fire severity than by current landscape patterns. Hence, models that represent the effects of climate change on boreal forests could improve their accuracy by including dynamic responses to fire disturbance.

Citation

Bernhardt, Emily L.; Hollingsworth, Teresa N.; Chapin, F. Stuart, III. 2011. Fire severity mediates climate-driven shifts in understorey community composition of black spruce stands of interior Alaska. Journal of Vegetation Science. 22: 32-44.