The area of east-central Minnesota known as the Mille Lacs Uplands and Glacial Lake Superior Plain subsections includes all or parts of Aitkin, Benton, Carlton, Chisago, Crow Wing, Isanti, Kanabec, Mille Lacs, Morrison, Pine, and Sherburne counties.
The soils of the Mille Lacs Uplands are coarse-textured near the southwestern edge of the region but become increasingly clayey to the northeast. The forests in areas of coarser drift (clay, silt, sand, gravel, and boulders deposited by glaciers) are dominated by northern red oak, while areas of clayey soil have forests of sugar maple, aspen, and birch.
Sandy terraces along the St. Croix River and small sand plains in other parts of the section have fire-dependent woodlands or forests of jack pine, bur oak, northern pin oak, and aspen. Fire-dependent pine, oak, and aspen forests are also present occasionally with mesic hardwood forests on coarse till and drumlins (teardrop-shaped hills of rock, sand, and gravel). Peatlands and other wetland communities are present mostly as inclusions within the broad areas of hardwood forest.
The small region near Duluth called the Glacial Lake Superior Plain is composed mostly of clayey sediments. The landscape is highly dissected by the Nemadji River and its tributaries, characterized by steep-sided ravines. The ravine slopes support wet-mesic forests of aspen and paper birch mixed with conifers such as white spruce, balsam fir, northern white cedar, and white pine; and mesic forests of sugar maple, basswood, and paper birch. High areas between the ravines represent flat, clayey, poorly drained remnants of the glacial lake bed. These sites most commonly have wet forests dominated by black ash mixed with northern white cedar and yellow birch.
Recommended trees and plants
*This species of red oak is most susceptible to oak wilt. Check your area’s current oak wilt risk.
**Due to Dutch elm disease, only plant disease-resistant varieties of American elm.
The following plants native to this region are also found further south. They should be well-equipped to adjust to our climate as it becomes warmer and wetter. These native plants also provide diverse benefits to microfauna, such as pollinators, other insects, birds and bats.
Creating climate refugia
Models of the state’s future climate may not favor the survival of some species you currently see in your woods. However, that doesn’t mean these species don’t hold intrinsic ecological, cultural or economic value. You can work to retain these species in your landscape and protect them from the impacts of climate change by creating forest refugia.
Species in this region that may be most vulnerable to climate change, pests and diseases:
- Black ash (Fraxinus nigra), white ash (Fraxinus americana) and green ash (Fraxinus pennsylvanica) are projected to do well in warmer and wetter climates but are all extremely vulnerable to emerald ash borer. Black ash is a cultural and ecological keystone species in northern Minnesota and is an essential part of Minnesota’s forests. If ash is present in your woodland, learn more about managing ash woodlands in response to emerald ash borer.
- Blue beech (American hornbeam, musclewood; Carpinus caroliniana) is projected to be vulnerable to climate change in this region. This species is often found in the understory of hardwood forests and therefore tolerates full shade. Consider thinning from below to open up growing space in the understory for this species.
- Butternut (Juglans cinerea) is projected to tolerate a changing climate, but it is extremely vulnerable to butternut canker, a fungal disease that has devastated populations of butternut across the northeast U.S. Butternut is a Minnesota endangered species and therefore cannot be bought commercially. A permit from the Department of Natural Resources is required to collect, transport, or possess butternut seeds and other parts of the tree.
- Red pine (Pinus resinosa) and jack pine (Pinus banksiana) are projected to be vulnerable to both a warmer and wetter climate in this ecoregion. Consider thinning existing pine stands to promote sufficient growing space. Harvesting in gaps can also promote a diversity of species, age classes, and structures that will improve the resilience of the stand. Learn more about managing red pine and jack pine stands.
- Balsam fir (Abies balsamea) is projected to be vulnerable to a changing climate in this ecoregion. Balsam fir provides many benefits to wildlife including moose and white-tailed deer, but also increases the fuel load for forest fires. In this region, consider diversifying stands with a large component of balsam fir to mitigate fire risk while still maintaining the winter food source and thermal cover provided by balsam fir.
- Bigtooth aspen (Populus grandidentata), quaking aspen (Populus tremuloides) and balsam poplar (Populus balsamifera) are projected to be vulnerable to a changing climate in this ecoregion. These species regenerate by root suckering (sprouting), and these aspen stands provide many benefits to wildlife throughout their life cycle. Aspen species are also critical for Minnesota’s forest product industry. Harvesting in gaps can also promote a diversity of species, age classes, and structures that will improve the resilience of the stand. Learn more about managing aspen forests.
- Slippery elm (Ulmus rubra) is also projected to do well but is susceptible to Dutch elm disease. With no disease-resistant cultivars of slippery elm currently available, landowners should be cautious in choosing where to encourage this species.
- White spruce (Picea glauca) and black spruce (Picea mariana) are common conifer species often found on both wet and dry sites, including bogs. These species are projected to be vulnerable to climate change in this region. Consider planting these species with a mix of climate-capable species (listed below) on cool, moist sites to promote diversity and improve resilience.
- Black willow (Salix nigra) is commonly found in wet areas, including along the margins of ponds and lakes. Black willow provides food and habitat for many species of wildlife, including birds, mammals, and insects. This species is projected to be vulnerable to climate change in this region. Black willow is projected to respond somewhat poorly to a warmer climate, so consider promoting this species on cool, moist sites.
Potential future tree species
As our climate changes, some tree species might be able to move into new areas as habitat becomes more suitable. Climate scientists with the USDA Forest Service have identified tree species with migration potential in the Mille Lacs Uplands and Glacial Lake Superior Plain.
Planting species not historically found in the region does carry some risk. Before you plant, learn more about assisted migration strategies, and work with a forester or another natural resource professional to determine the best options for your land and goals.
Woodlands of Minnesota Handbook
The Minnesota Department of Natural Resources has created a series of woodland handbooks that provide landowners with information on their region’s conditions, frequent challenges, and advice on setting and reaching management goals. The Mille Lacs Uplands and Glacial Lake Superior Plain handbook includes information on wildlife, plants, invasive species, geology, landscape and watershed management for this special region of east-central Minnesota.
Reviewed in 2024