Functions and dynamics of boreal bog vegetation under global changes

Abstract

Vegetation with a dominance of Sphagnum and low cover of vascular plants have been recognized as a core component that controls several biogeochemical processes and vital services of boreal bogs, especially in greenhouse gas emissions. The boreal bog plants are long-term adapted to cold, low available nutrient conditions. Therefore, global warming and increases in nitrogen (N) availability may change the boreal bog vegetation and alter the primary services of these boreal ecosystems. This study utilized long-term field experiments to examine the function of vegetation composition in regulating N₂O emissions and dynamics of boreal bog vegetation to the projected global changes. Results show that graminoids accelerate N₂O emissions from boreal bogs under N-enriched conditions. This study also indicates that the long-term warmer (W) and N-enriched conditions enhance vascular plant growth, especially graminoids. By contrast, these environmental changes result in rapid losses of Sphagnum in boreal bogs. Vascular plants mitigate the decline of Sphagnum, although the facilitation by vascular plants can not eliminate the decreases in Sphagnum mosses due to the warming and high N availability. These findings suggest that vegetation might switch to the dominance of vascular plants under warmer, N-enriched conditions, stimulating N₂O emission in boreal bogs.