The Cold Regions Research Centre and the Biology Department are pleased to host the following seminar. Please distribute to those who may be interested. All are welcome.
Disturbance as a catalyst and driver of change in the boreal forest
Dr. Jill Johnstone
Biology, University of Saskatchewan
Date: Friday, October 17
Time: 2:30 PM
Location: Science Building N1044
Pre-seminar coffee will be available in N1046 at 2PM
The rapid pace of climate change has raised warning flags for many researchers who anticipate large changes in forest systems as a direct result of warming climate conditions. In the boreal forest, changes in tree mortality and growth responses under recent climate conditions suggest that forests are experiencing increasing environmental stress. However, the substantial inertia of intact forest communities means that large scale changes in forest structure are most likely to occur in association with disturbance. In addition, the characteristics of a disturbance itself can push a system in different directions, acting as an additional driver of change. Here I discuss results from seeding trials in post-fire forests of Alaska that help identify conditions that support forest recovery to pre-fire conditions (=resilience) versus those that may be pushing the system into new configurations. Vegetation legacies associated with organic layer accumulation and propagule availability are a key factor supporting resilience across fire cycles. Unusual disturbance conditions that disrupt these legacies, such as increases in fire frequency or severity, open the playing field for new community configurations to develop. Interactions between landscape gradients, vegetation legacies, and disturbance characteristics give rise to certain parts of a landscape likely being more vulnerable to rapid changes in forest cover than others. These studies of fire and succession in the boreal forest suggest that predicting near-term, transient responses to climate change will require a landscape-explicit understanding of how environmental conditions, vegetation legacies, and disturbance characteristics interact to drive patterns of forest resilience under climate change.
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