Extreme Climate and Trees

Stretching from Maine through New York, the Northern Forest is home to 2.3 million people, and its vast natural resources have a marked environmental and economic impact.

Historically, Maine’s forests have had an abundance of natural regeneration – the process by which older trees provide seeds that fall, germinate, and ultimately restock the site. A recent study of regeneration in eastern U.S. national park woodlands found that Acadia’s forests are in a “secure” condition. But, with the rapidly rising rate of extreme climate events like heat waves, drought, and mid-winter thaws, we don’t really know what our future forests will look like or how long natural tree regeneration will be enough to sustain them.

University of Maine researchers Jay Wason, Nicole Rogers, and Yongjang (John) Zhang, along with Schoodic Institute’s Nick Fisichelli, have initiated a new project funded by Northeastern States Research Cooperative to determine not only what our future forests will look like, but what land managers can do about it. The focus of this project is how tree regeneration in the Northern Forest will respond to extreme drought, heat, and midwinter warming events in order to better inform forest management strategies.

The experiment, run at six different site locations across Maine, will simulate future climate conditions throughout the Northern Forest region. At each site saplings are sectioned off into boxed plots containing one tree of 10 different species. The researchers will study the impacts of drought conditions, heatwave conditions, and simultaneous drought and heatwave conditions. Drought conditions will be implemented by covering the tree plots to exclude rain. Heatwave-like conditions will be mimicked by constructing a clear greenhouse structure around each plot. The second experiment, conducted in Orono, Maine, will simulate midwinter thaws of varying lengths on the same 10 tree species by moving select groups of plants into a greenhouse for differing time spans during the winter.

The researchers hope that the experiments will identify the forest tree species that are best and least adapted to future extreme climate conditions. And the research team hopes to narrow the critical information gap that exists between scientists and forest managers by incorporating managers and community members into the research process.

“[Working alongside forest managers] helps make sure that we’re not just focusing on our one little thing that we think is important because we want to publish papers about it. We’re focusing on things that people are actually concerned about and want to know more about for their forests,” said Jay Wason.

Unlike other heavily forested areas of the United States, the Northern Forest is largely privately owned. This means the interpretation of and implementation of the Extreme Climate Impacts on Trees study will require close collaboration among scientists, managers, and landowners.

The anticipated completion date of the project is well over a year away.


Written by Catherine Devine.