SUCCESSION OF BIOGENIC VOC EMISSIONS IN NORTHERN MICHIGAN

摘要

The changing composition of a northern lower Michigan forest through secondary succession was explored to predict future isoprene and monoterpene emissions. Northern lower Michigan forests currently have a high proportion of strong isoprene emitting plant species such as bigtooth aspen (Populus grandidentata) and northern red oak (Quercus rubra). Bigtooth aspen is only present at current proportions due to extreme disturbance from fire and logging in the early 1900s that has not been repeated since. The relatively short life span of bigtooth aspen suggests that northern lower Michigan forests are about to go through a major transition. Bigtooth aspen will be replaced by trees with much lower isoprene emissions and higher monoterpene emissions. Isoprene currently dominates reactions with oxidants in the lower troposphere in northern lower Michigan, but this will change as bigtooth aspen die and are replaced by pines (Pinus strobus and P. resinosa) and red maple (Acer rubrum). Successional trajectories for different climate scenarios show that the proportion of white pine to red maple in the future forest will determine the magnitude of changes in the chemistry of the lower troposphere.