Abstract

Northern Minnesota’s climate is changing and tree populations on the Superior National Forest (SNF) must either adapt, migrate, or face possible local extinction. However, the predicted changes in climate exceed natural migration and adaptation abilities of many forest trees. Assisted Migration (AM) is a climate adaptation strategy that will help the SNF increase climate resiliency by planting climate adapted tree species and genotypes strategically on the landscape.

Background on AM

Assisted migration is a tool that, when implemented appropriately, can help ensure that during reforestation the right tree (considering both source population and species) is planted in the right place. The primary motivations for implementing AM on the landscape are to maintain forest health and productivity, preserve associated ecosystem services and economic value, and to increase the likelihood of maintaining trees as dominant life forms in forested ecosystems. Planting the wrong tree on a site, either by planting maladapted trees with lower chances for survival or by unintentionally introducing an invasive species, can result in more harm than good and can potentially decrease the resiliency of the site. Therefore, it is crucial that tree planting practices incorporate scientific and Tribal cultural resource considerations. This portion of the plan presents considerations on both the potential risks and benefits associated with AM of forest trees.

Tribal Treaty and Cultural Resource Considerations

The SNF lies within the Ceded Territory of the Treaty of 1854. Federal courts have acknowledged and recognized Tribes that were signatories to the 1854 Treaty as the original inhabitants of the land who retain usufructuary rights extending throughout the entire northeast portion of the State of Minnesota. SNF land management decisions have the potential to affect the treaty rights and cultural values of Tribal communities. Climate adaptation decisions will influence how Tribal citizens maintain their rights across the Ceded Territory in the years ahead. This portion of the plan describes the rationale for discussing assisted migration through formal consultation and informal collaboration with Tribes. Based on input from Tribal natural resources staff and community members, this plan stipulates that assisted range expansion (ARE) and assisted species migration (ASM) should be reviewed through formal consultation with Tribal leadership.

Genetic Considerations

This section of the plan summarizes information from peer-reviewed literature and technical reports on genetic tests of tree species of interest for planting on the SNF. Based on these reviews, we developed seed movement guidelines for nineteen major and minor tree species. Summary tables for the eight major species of interest are presented and include information on genetics, cone and seed traits, insect and disease susceptibility, palatability to browse, maximum transfer distance and species range-expansion potential. For the eleven minor species with limited genetic data available, short summaries are provided along with information on genetic diversity and gene flow. In general, most tree species reviewed have high genetic diversity and therefore, presumably high capacity for adaptation to new conditions. Seed sources from short distances south of the planting site do as well or better than local material. The results of this review support Assisted Population Migration (APM) as a low-risk adaptation strategy.

Logistics for Seed Sourcing

Implementing AM will require developing new logistical processes for delivering genetically appropriate tree seedlings for planting sites. The SNF reforestation program is integrated with the United States Department of Agriculture Forest Service (USDA Forest Service) Region 9 seed orchard and tree nursery facilities. For some species, USDA Forest Service seed orchards are already available and will provide adequate assisted population migration (APM) tree seed for the foreseeable future. For others, orchards will need to be developed now to support reforestation in the mid-21st century. Until genetically appropriate USDA Forest Service seed orchards are productive, collections to support APM will need to occur from partner seed orchards, or more often, from partner lands or other National Forests. This section of the plan includes a list of partners, maps for guiding seed sourcing decisions, and guidance on seed collection best practices.

Implementation Guidelines

Implementing assisted migration on the SNF will require additional considerations beyond the scope of the current reforestation program. This section of the plan outlines guidance for when, where, and how to use the three different types of AM (Assisted Population Migration (APM), Assisted Range Expansion (ARE) and Assisted Species Migration (ASM)) appropriately. A companion document titled “Superior National Forest Assisted Migration Implementation Guide” provides more detail on this topic including a decision flowchart, description of AM geospatial information and instructions for entering AM information into the database of record.

Monitoring

A monitoring protocol will be used to track survival and condition of planted assisted migration stock. This protocol is distinct from the stocking survey protocol currently being used on the SNF. AM data will be tracked and reviewed by the Forest Ecologist and Silviculturist for long-term data archiving and analysis. Climate conditions from nearby weather stations will also be monitored. If survival or condition of assisted migration stock is substantially lower than expected, data will be reviewed to determine potential causes for low performance/survival and identify potential remedies if necessary.

Research Needs

This section of the plan provides an overview of key research topics and questions related to assisted migration in Northern Minnesota and the SNF. Future research on these topics can help inform decisions on when, where, how, and whether to implement assisted migration on the SNF. Past and ongoing research will also provide important insights and a list of projects is included as an Appendix.

Affiliated Organizations

U.S. Department of Agriculture (USDA)

The United States Department of Agriculture (USDA) works to support the American agricultural economy to strengthen rural communities; to protect and conserve our natural resources; and to provide a safe, sufficient, and nutritious food supply for the American people. The Department’s wide range of programs and responsibilities touches the lives of every American every day. This factsheet provides information about some of our agencies and offices, their missions, responsibilities, and services they provide.

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USDA Forest Service

The U.S. Department of Agriculture Forest Service is a Federal agency that manages public lands in national forests and grasslands. The Forest Service is also the largest forestry research organization in the world, and provides technical and financial assistance to state and private forestry agencies. Gifford Pinchot, the first Chief of the Forest Service, summed up the purpose of the Forest Service—"to provide the greatest amount of good for the greatest amount of people in the long run."

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