• Start-up
  • Planning
  • Action
  • Evaluation

The Nature Conservancy (TNC) worked with several partners and a consulting forestry firm to re-write Caroline Lake Preserve's forest management plan to incorporate actions to help adapt forests to climate change, while meeting TNC's management objectives. This plan was prepared for the State of Wisconsin's Managed Forest Law tax incentive program by Compass Land Consultants, Inc, and finalized in February 2016.  TNC will now move forward and implement the plan over the next 10 years.

The Nature Conservancy’s Caroline Lake Preserve in northern Wisconsin provides a real-world example of how climate change adaptation can be incorporated into sustainable forest management. It is one of multiple adaptation efforts in the area that show how forest management actions can enhance the forest’s ability to cope with changing conditions while meeting a variety of landowner goals.
Matt Dallman (TNC) leading a tour of the Caroline Lake Property
Risk categories for overstory trees across the Caroline Lake Preserve under a mild climate change scenario.

Project Area

Locator map showing the Caroline Lake Preserve.
The Caroline Lake Preserve is located at the headwaters of the Bad River in northern Wisconsin, about 20 miles south of Lake Superior. The Caroline Lake Preserve and surrounding forest lands help to maintain the Bad River’s clean water and contributes to the health of the Kakagon/Bad River Sloughs, the largest and healthiest fully-functioning estuarine system remaining in the entire upper Great Lakes. The Nature Conservancy in Wisconsin has worked throughout the state since 1960 to conserve forests, wetlands, prairies, and streams. The Preserve contains 1,044 acres of forest acquired from industrial ownership in 1997, and TNC has developed a management plan that provides for sustainable forest management and protection of natural processes, water quality, and biodiversity.

Management Goals

Matt Dallman (TNC) leads a tour at the Caroline Lake Preserve. Photo credit: Jane Severt.
The goal in the Conservancy’s efforts regarding this property is to reach a balance between enhancing the quality of water resources, improving diversity of forest communities and wildlife resources along with sustaining jobs, timber management, and timber revenue. Prior to considering the effects of a changing climate on the Preserve, management goals for the property included:
  • Maintaining forest communities that were historically characteristic of these site types over a natural range of ages, patch sizes, and compositions.
  • Encourage mid- to late-successional forests that emulate natural disturbance dynamics (such as gaps) and increase under-represented species and age diversity.

Climate Change Impacts

A group of scientists and forest managers from TNC, NIACS, Compass Land Consultants, and the Wisconsin Department of Natural Resources used the Adaptation Workbook from Forest Adaptation Resources: Climate Change Tools and Approaches for Land Managers to evaluate the potential climate change impacts on the Caroline Lake Preserve. Potential climate change impacts that are of particular interest at the Caroline Lake Preserve include:
Changes in the area’s hydrology due to warmer winter temperatures and changing precipitation patterns. Warming is expected to be greatest in winter, which may reduce the large amount of lake-effect snow, leading to changed seasonal conditions and increase
Reduced water levels or water levels that fluctuate greatly between seasons as a result of changes in precipitation patterns, particularly in forested wetlands. These changes could increase stress on forests and reduce their ability to provide clean wate
Declines in habitat for many of the preserve’s tree species, such as black spruce and balsam fir. Some forest types, such as lowland conifers, may be at a particular disadvantage, especially if large hydrological changes also occur.
Increases in habitat for some of the preserve’s trees species. Red oak, white pine, and several other species that currently occur in parts of the preserve are projected to fare better in the future. In many parts of the preserve, the diversity of tree s

Adaptation Actions

Project partners identified a number of potential adaptation actions with the overarching intent to maintain the resilience of the forest to changing conditions. In the northern hardwood forest, actions to maintain and enhance tree species diversity were prescribed to reduce the risk from climate change-related declines in the dominant species. This included the use of group selection and shelterwood harvests to enhance natural regeneration of mid-tolerant species. Several of these species, including northern red oak and black cherry, are currently present on the property in relatively low amounts and are projected to fare better under climate change relative to other species that are currently present. Eastern white pine was also identified as a desirable species. Although it is projected to decrease under some climate scenarios, the species is at a lower risk of decline than other native conifers.

The managers generally viewed the proposed actions as slight adjustments, rather than a significant departure, to the current management trajectory. Additionally, several “contingency plans” were discussed for responding to disturbances or other unforeseen events. For example, lowland hardwood forests were identified as at risk from altered hydrologic regimes and reduced late growing season soil moisture from climate change, introduction of the emerald ash borer, or a combination of these threats. Although no active management is currently planned in these stands, swamp white oak and bur oak  were identified as two potential species that could be planted in lowland hardwood forests to maintain forest cover if intervention was deemed necessary. These species are not currently present on the property but can be found in localized areas in northern Wisconsin, which would represent a small degree of assisted migration.

A select list of the adaptation actions selected from the Adaptation Workbook and recommended in the property's updated management plan includes: 

Area/Topic
Approach
Tactics
Northern hardwoods
5.2. Maintain and restore diversity of native species.
Use single-tree selection and targeted gaps and seed trees to maintain or enhance diversity of mid-tolerant species
Where opportunities exist, promote white pine, black cherry, yellow birch, northern red oak, and other desirable species that have a lower risk of declining due to climate change
5.1. Promote diverse age classes.
Use large group selection or shelterwood harvests to increase northern red oak component in areas where natural regeneration is present.
4.2. Prioritize and maintain sensitive or at-risk species or communities.
Reserve high-quality hemlock pockets on less vulnerable sites to serve as refugia.
Lowland Hardwoods
1.2. Maintain or restore hydrology.
2.1. Maintain or improve the ability of forests to resist pests and pathogens.
Diversify stands through thinning, group selection, or other techniques.
9.2. Establish or encourage new mixes of native species.
Consider experimental plantings of swamp white oak or bur oak.

Monitoring

Managers from TNC and the consultancy responsible for the property management also identified forest inventory data as an integral component of monitoring the effectiveness of adaptation actions over time. Permanent forest inventory plot locations were established in randomized locations across the property, and a comprehensive inventory was performed to document stand characteristics and ecological attributes. The robust inventory provided a useful baseline for prescribing management activities for adaptation. For example, data on tree species abundance were used to calculate tree species richness and diversity evenness and provided an indication of the relative risk associated with the loss of different tree species. Additionally, the presence of advanced regeneration of northern red oak and black cherry (tree species that may be better adapted to future conditions) was evident in the inventory data. In the future, inventories repeated at approximately 10-year intervals will be used to evaluate whether the selected management activities increase the abundance of these species in the understory and eventually the overstory. The monitoring list of Key Ecological Attributes for the property includes:
Tree species diversity (richness and evenness)
Large snags and large coarse woody debris
Established regeneration and desirable seedlings

Project Documents

Next Steps

TNC will be implementing the prescribed management actions in this management plan for at least the next 10 years. Continuous monitoring of Key Ecological Attributes outlined in the plan will reveal whether sufficient progress is being made toward ecological goals over time.

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Keywords

Assisted migration
Insect pests
Lowland/ bottomland hardwoods
Lowland/ wetland conifers
Management plan
Upland hardwoods
Water resources

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