- Bothwell, Karin
University of Maine
Regulations protecting habitat of forest-dwelling species often impact forest management practices. Those impacts may be mutually beneficial to both wildlife and forestry or they may lead to unanticipated negative outcomes, such as an associated economic cost compared to management free from habitat regulations. One example of a regulation that impacts forest management is the zoning of winter habitat of white-tailed deer (Odocoileus virginianus) in Maine, where deer abundance has been consistently below socially desired levels in most areas of the State since the 1970s due in part to the heavy toll of severe winter weather. To mitigate winter-related mortality, the Maine Department of Inland Fisheries and Wildlife (MDIFW) sought to establish protected zones for winter deer habitat (or deeryards) in areas of dense softwood forest cover and traditional deer use. MDIFW also developed an approval process to ensure timber harvests maintained zoned habitat. While there are benefits to supporting the deer population, there are also potential drawbacks to managing for winter habitat on land used primarily for timber production. This thesis assessed both the stand-level economic and landscape-level habitat implications of this wildlife policy.
The first research component evaluated the economic implications of Maine’s winter deer habitat zoning policy by quantifying the cost to landowners of managing deeryards on their land. Using the Forest Vegetation Simulator, I modeled six silvicultural management scenarios and calculated the financial outcomes by wood product stumpage price. Results were dependent on site and the influence of landowner objectives on past forest management and ranged from lower harvest revenues inside deeryards because of less stand tending to higher revenues inside deeryards because of commercially favorable species composition. Adaptive implementation of novel silvicultural regimes holds opportunities for positive habitat-level outcomes with commercially viable timber management. Clearer habitat management guidelines based on standard forest inventory metrics may facilitate the harvest approval process and help foresters realize the potential of silvicultural management within deeryards.
In the face of persistently low deer numbers in northern Maine, MDIFW is reevaluating its guidelines regarding maintenance of habitat features within zoned deeryards and the biological basis of zone delineation. I used maps of tree species abundance and harvest history to evaluate and compare forest characteristics within existing zoned deeryards to areas that would be delineated based on a proposed new zoning method. This analysis of northern Maine led to identification of areas that currently exhibit the desirable characteristics of white-tailed deer winter habitat and a quantitative evaluation of that habitat’s distribution. The original zoned deeryards effectively protected patches of softwood-dominated forest from intensive timber harvests. Many patches of potential wintering habitat persist across northern Maine and tend to be aggregated on the landscape. These findings provide new information to aid in revision and improvement of winter deer habitat regulations and guidelines and to mitigate their unintended side effects.