Project Area
The Nulhegan Basin is a natural landscape feature centered on a crater-like “basin” roughly 10 miles across located in northeastern Vermont. The Basin is the largest forested tract within the Silvio O. Conte National Fish and Wildlife Refuge, which is composed of several refuges within the Connecticut River watershed in New England. The forest in the Basin has a long history of logging and industrial forest management that greatly affected the forest prior to the sale of forest lands from Champion Paper to the US Fish and Wildlife Service and other conservation organizations in the late 1990s.
The project area consists of approximately 550 acres of lowland mixed conifer forest and associated ecosystems within the Nulhegan Basin Division of the Refuge. The site is largely even-aged and dominated by balsam fir, with little structural diversity. A greater diversity of species, including red spruce, white pine, and northern white cedar, would be expected in the absence of the site’s management legacy.
The project area consists of approximately 550 acres of lowland mixed conifer forest and associated ecosystems within the Nulhegan Basin Division of the Refuge. The site is largely even-aged and dominated by balsam fir, with little structural diversity. A greater diversity of species, including red spruce, white pine, and northern white cedar, would be expected in the absence of the site’s management legacy.
Management Goals
The overall management of the Nulhegan Basin Division is focused on wildlife habitat. Blackburnian warbler, Canada warbler, and rusty blackbird are focal species that are supported by a mosaic of spruce-fir, northern hardwood, and northern hardwood-conifer forest communities.
Specific management goals for the project area include: Improve vertical and horizontal canopy diversity, improve tree species diversity in both overstory and understory, increase desirable species such as red spruce, white pine, northern white-cedar, reduce the preponderance of balsam fir, increase structural complexity (including downed woody material, tip-up mounds, and legacy trees), and create a greater diversity of wildlife habitat.
Climate Change Impacts
Climate change is expected to impact forest ecosystems in Vermont into the future. These include warming of 5.3 to 9.1 °F by late century (2071-2100), with fewer days below freezing and an increase in the growing season by three weeks. On average, the climate is projected to get wetter with more frequent and damaging extreme storms, including intense rainfall that may cause soil erosion. Timing of precipitation is expected to change, with longer periods between rain events increasing the risk of moisture deficits and drought during the growing season. These changes may affect invasive plant and pest and disease pressure on forests in addition to limiting opportunities for winter harvesting. Northern species such as sugar maple, yellow birch, and white birch that comprise much of the canopy on the site are predicted to decline in the region. Northward migration of future-adapted species may be slower than the expected changes in climate that would create suitable habitat for these species, resulting in declining forest health and productivity over time.
Challenges and Opportunities
Climate change will present challenges and opportunities for accomplishing the management objectives of this project, including:
Challenges
Altered precipitation patterns, including increased seasonal precipitation, extreme precipitation events, and drier summer conditions could alter the hydrology of the site and stress trees depending on local and microsite conditions.
Many of the northern species that are dominant on the site are projected to decline regionally as a result of climate change, including balsam fir, red spruce, and northern white-cedar.
The low levels of diversity in the project area reduce the adaptive capacity of the system to cope with species changes from climate change and other stressors.
impacts from insect pests, such as the balsam woolly adelgid and spruce budworm.
White-tailed deer are expected to eventually increase as winters become less severe and moose competition lessens.
Opportunities
The position and shape of the Nulhegan Basin causes cold-air pooling and a colder microclimate within the basin, which is expected to help maintain colder conditions in the project area into the future relative to the broader landscape.
Adaptation Actions
Project participants used the Adaptation Workbook to develop several adaptation actions for this project, including:
Area/Topic
Approach
Tactics
3 research treatments - Patch clearcut with reserves
5.1. Promote diverse age classes.
5.2. Maintain and restore diversity of native species.
5.3. Retain biological legacies.
5.2. Maintain and restore diversity of native species.
5.3. Retain biological legacies.
Treatments will be approximately 15 acres
Each treatment unit will feature three, 3-acre patch cuts with 10% retention of overstory trees
Fell or tip 8-10 whole trees per acre for downed dead wood
In patch clearcut areas, plant seedlings of historically-important conifer species expected to be adapted to future conditions (red spruce, white pine, northern white cedar, hemlock) in the spring following harvest (2022)
3 research treatments - Variable density thinning
5.1. Promote diverse age classes.
5.2. Maintain and restore diversity of native species.
5.3. Retain biological legacies.
5.1. Promote diverse age structure
5.2. Maintain and restore diversity of native species.
5.3. Retain biological legacies.
5.1. Promote diverse age structure
Treatments will be approximately 15 acres
20% of the total treatment area will feature approximately half-acre gaps in areas of advanced regeneration
20% of the total treatment area will feature approximately half-acre patch reserves in ecologically sensitive areas or around legacy features such as snags or cavity trees
60% of the total treatment area will be thinned to approximately 110-120 ft2/acre
Retain 1-2 legacy trees in each gap as future downed dead wood
Fell or tip 8-10 whole trees per acre for downed dead wood
In gap areas, plant seedlings of historically-important conifer species expected to be adapted to future conditions (red spruce, white pine, northern white cedar, hemlock) in the spring following harvest (2022)
Entire project area (all treatments)
1.1 Reduce impacts to soils and nutrient cycling.
1.2. Maintain or restore hydrology.
1.3. Maintain or restore riparian areas.
5.3. Retain biological legacies.
9.1. Favor or restore native species that are expected to be adapted to future conditions.
9.4. Protect future-adapted seedlings and saplings.
1.2. Maintain or restore hydrology.
1.3. Maintain or restore riparian areas.
5.3. Retain biological legacies.
9.1. Favor or restore native species that are expected to be adapted to future conditions.
9.4. Protect future-adapted seedlings and saplings.
Supplemental planting of historically-important conifer species expected to be adapted to future conditions in a subset of treatments (red spruce, white pine, northern white cedar, hemlock)
Limit red spruce removals
Apply herbivore browse protection on half of the seedlings planted in each treatment
Increase dead and down wood where opportunities exist
Winter harvesting and no harvesting in identified restricted areas (sensitive and inoperable areas)
Monitoring
Project participants identified several monitoring items that could help inform future management, including:
Tracking the success of natural regeneration and planted seedlings
Evaluating overstory and understory structure and species diversity in response to the silvicultural treatments
Assessing bird response to forest management, which may be able to be done passively with the use of sound recorders