Submission information
Green Hills Preserve Forest Adaptation
The Green Hills Preserve Forest Adaptation project is focused on increasing tree species diversity and forest complexity to promote climate resilience, diverse wildlife habitat, and forest carbon sequestration and storage while providing sustainable forest products. Spongy moth, beech bark scale disease, beech leaf disease, and hemlock wooly adelgid are either currently affecting the site or anticipated to in the near term. This site includes a long-term experimental area developed in partnership with the University of Vermont.
Site Location
Conway, New Hampshire
Managed by The Nature Conservancy, the Green Hills Preserve is just to the east of Route 16 in Conway. The project area is in the southern part of the preserve, which was protected in partnership with the New Hampshire Fish & Game Department in 2012.
44.031136
-71.065916
Contact TNC
The Nature Conservancy
+1 603-224-5853
Stand Information
This project focused on treating two stands. Stand 1 is 732 acres and dominated by American beech and northern red oak. Stand 2 is 312 acres and dominated by eastern hemlock, American beech, and red maple.
Mixedwoods
Pre-treatment, both stands were in the stem exclusion stage.
spongy moth
beech bark disease
other foliage / shoot disease (known)
Predominantly Canaan-Redstone
Pre-treatment Conditions
In Stand 1, past harvesting was not based on silviculture and focused on removing the more commercially valuable stems, primarily red oak and white pine. Because of the spotty, partial nature of past harvesting, shade tolerant beech regeneration became widely established throughout much of the stand. For Stand 2, past harvesting was light in nature but focused on removing the more commercially valuable red oak, white pine, and red spruce. The resulting regeneration was dense in some areas, consisting of a mixture of American beech, eastern hemlock and other hardwoods. Where hemlock occurred in the understory, it was in patches and small groups.
Stand 1: Northern red oak, American beech, Red maple Stand 2: Eastern hemlock, Red maple, American beech
Quercus rubra (northern red oak)
36%
Fagus grandifolia (American beech)
30%
Acer rubrum (red maple)
8%
Stand 1 – 129 sq. ft. acre Stand 2 – 150 sq. ft. acre
Stand 1 was heavily impacted by beech-bark- scale disease and spongy moth outbreaks that occurred in 2021 and 2022.
Silviculture Prescription
The Green Hills Preserve is 5,567 acres managed by The Nature Conservancy in Conway, New Hampshire. The preserve includes mixed hardwood forests, northern hardwood forest, exposed rocky ridge communities dominated by red pine and pitch pine, a variety of headwater streams and wetlands, and provides rare species habitat. This project is focused on a 1,328-acre area in the southern part of the preserve that was acquired in partnership with the NH Fish and Game Department in 2012. A forest inventory completed for this area in 2022 revealed low tree species diversity, limited deadwood pools, and generally even aged forest conditions. Many of the stands within the project area are dominated by American beech in both the canopy and advance regeneration, which has been heavily impacted by beech-bark-scale disease. A spongy moth outbreak that defoliated ~40,000 acres in the surrounded area in 2021 and 2022 impacted the site and there has been significant mortality in the overstory northern red oak as a result. The outbreak also caused widespread mortality of eastern hemlock in both the canopy and advance regeneration, exacerbating the tree species diversity and beech dominance issues. Beech leaf disease is currently spreading throughout the state and is anticipated to impact the project area in the near term. This may help to address the issue of beech dominance, but the loss of this species may impact wildlife populations with the associated reduction in hard mast. The silvicultural treatments implemented at the site have been aimed at recruiting diverse, shade intolerant tree species to sustain functional traits at the site; creating complex structures; recruiting and developing deadwood pools; and building resilience to pests and pathogens and future climate impacts. A portion of the site is part of an experimental area developed in partnership with the University of Vermont. Long-term monitoring data is being collected in this area to assess forest health, carbon stocks, and growth and survivorship of regeneration and planted trees.
• Increase the number of large snags and cavity trees to 4-7/acre >20” DBH and the amount of coarse woody debris to 8-10 large (>20”) downed logs/acre with various stages of decay. • Implement regeneration harvests, including patch cuts, thinning, and crop tree release, that result in diverse age classes and structures. • Establish reserves within riparian areas, steep slopes, and areas with good site conditions where large legacy trees and other old forest characteristics can develop rapidly. • Implement harvests that reduce competition for resources (light, moisture, nutrients) and maximize the ability of the residual stands to resist and recover from the impacts of forest pests and pathogens (spongy moth, hemlock wooly adelgid, southern pine beetle). • Retain “clean” beech within stands where possible. • Plant species adapted to future climate, including mast producing species to benefit wildlife. • Implement BMP’s for reducing the potential impacts of hemlock wooly adelgid and retaining hemlock on the site.
• Enhance the compositional and structural diversity of the forested habitats to build climate resilience and provide habitat for State Wildlife Action Plan (SWAP) species. • Manage for old forest characteristics within a portion of the site to develop biological legacies, promote resilience, and provide old forest habitat for SWAP species. • Promote diverse regeneration to provide multiple climate adaptation pathways and ensure diverse forested habitats for SWAP species. • Increase the potential for carbon sequestration and storage above and below ground by improving forest health. • Mitigate the negative impacts of forest pests and pathogens by building forest health. • Protect and manage for rare species and exemplary natural communities that are present within the site.
Stand 1: Patch cut with reserves. Remove all overstory trees in one, 3-acre and one, 5-acre patch within each treatment unit. Retain existing snags and cavity trees and 10-15 overstory trees as within-patch legacy trees. Create two additional 3-acre patches and protect with “slash-walls” to protect the regeneration from herbivory. Crop tree release. Apply crop-tree release to 50 crop trees per acre by releasing at least 2 sides of crop tree crowns. Fewer than 50 crop trees per acre can be released where stocking is already lower. Target better-quality oak for crop trees, although other species can also be selected where options for oak are not present due to spongy moth impact. Residual target basal area will be 85-90 ft2/acre. Chemically control understory beech in half of these units using the “beech frill” technique. Plantings. Plant a mix of enrichment and future adapted tree species in portions of both the patch cuts and crop tree release areas. Stand 2: Hybrid single-tree and group selection with permanent legacy retention. Create single-tree (50 ft diameter; 0.05 ac) and small group openings (100 ft diameter; ~0.2 ac) in 10-20% of stand, targeting existing pockets of hemlock and red spruce advance regeneration where present. Retain all trees larger than 20” as permanent legacy trees. Stand wide basal area target should be 95-110 ft2/ac. Fell and leave 5-7 whole trees per acre (large, low value) for downed dead wood, pulling over to create tip-up mounds where possible.
Stand 1. Increase species diversity by recruiting shade-intolerant species such as northern red oak and white pine. Plant future adapted species not currently occurring at the site, including shagbark hickory, chestnut oak, white oak, and black birch.
Stand 2. Recruit and release eastern hemlock and red spruce. Supplement natural recruitment with enrichment plantings and eastern hemlock and southern genotype red spruce.
Stand 1. Clearcutting, crop tree release; Stand 2. Single tree selection and group selection.
- forest health
- climate change
- wildlife habitat
- carbon
See NIACS demo page:
https://forestadaptation.org/adapt/tnc-green-hills
Cut-to-length system
The silvicultural treatments were implemented largely as planned. However, the crop tree units within the experimental area were severely compromised by the spongy moth outbreaks. These outbreaks resulted in significantly more mortality of the overstory northern red oak than anticipated, which reduced the availability of high-quality crop trees.
Post-treatment
yes
As above, cut-to-length operation
Miscellaneous
This project was part of a revenue generating commercial timber harvest. It resulted in net proceeds to The Nature Conservancy, which are being reinvested in additional work at this site and other TNC preserves in New Hampshire.
Basal Area Pre Harvest Stand 1: Stand 2: ; Basal Area Post Harvest Stand 1: Stand 2: ; -----Trees Per Acre Pre-Harvest Stand 1: Stand 2: ; -----Mean Stand Diameter (inches) Stand 1: Stand 2:
Statistics
129
feet squared per acre
285
7.1 inches
Contact Information
Jeff Lougee
Director of Land Management
The Nature Conservancy
North Conway, New Hampshire. 03860