Date of Award

Winter 12-13-2019

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Forest Resources

Advisor

Mindy Crandall

Second Committee Member

Laura Kenefic

Third Committee Member

Aaron Weiskittel

Additional Committee Members

Anthony D'Amato

Abstract

While forest managers once sought primarily to produce sustainable revenue from harvests, there is now growing value placed on non-timber outcomes like wildlife habitat, climate adaptability, and carbon storage. When deciding how to manage land for the future, foresters and landowners must assess the many outcomes of forestry activities and be aware of the tradeoffs inherent to achieving different goals. Given the slow growth of trees relative to other commercial crops, it is rare to have the continuity of land ownership, researchers, and funding needed to follow a stand for a full rotation or to observe a tree from recruitment to maturity. Because a given forester will rarely see results of their management decisions decades in the future, long-term studies can help forest managers anticipate the results of treatments they apply. We examined effects of over 65 years of even-aged (uniform shelterwood) and uneven-aged (single-tree selection) silviculture and exploitive harvesting practices (diameter-limit cutting and commercial clearcutting) on a variety of silvicultural, economic, and ecological outcomes, using a long-term U.S. Forest Service study at the Penobscot Experimental Forest in central Maine, U.S. We found that while some treatments achieved their original objectives, changes in markets and growing awareness of ecological values (e.g. habitat provision and carbon storage) influenced our assessment of these outcomes today. For example, the shelterwood treatments successfully controlled species composition and structure, but those stands may not be resilient to environmental or market changes. Selection treatments created stands of high-quality, large trees and diverse habitat structures, but did not encourage species adaptable to future climate conditions. Exploitive harvesting encouraged climate change-resilient species like red maple, but led to poor tree quality, growth rates, and economic value. These findings underscore that we must consider outcomes beyond short-term wood production, and time may change how we interpret structural and compositional results as new objectives and socio-ecological contexts arise.

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