More than a dozen workers hike into a logged-over clearing and swing hoedads, the heavy steel tree-planting tools that resemble pickaxes. The sound of steel striking rock rings through the forest as the workers plunge the tools into the stony ground to find suitable soil for a tree.
“The guys have to hit five or even six times to find a spot where to plant,” says Sergio Villegas Moreno, a crew supervisor.
As his metal blade finds good dirt, a worker pulls a conifer seedling from the canvas bag at his hip, tucks the roots into the gash in the soil, pushes the soil firmly around the tiny tree, and skips ahead, swinging his tool again.
“We measure if it is a good day or not by the number of trees we plant,” says Moreno, as the crew spreads quickly across the clearing.
Tree-planting crews working for The Nature Conservancy last year planted more than 50,000 conifers in northeastern Minnesota to help restore a diverse mixture of the iconic trees that once made up 70 percent of the forest. Another 50,000 native conifers will be planted in 2018.
Site selection is critical to the project’s success. Cooler temperatures will be important as climate change creates tough growing conditions for boreal conifer species such as white pine, jack pine, white spruce, tamarack and white cedar. Some areas, such as the western Boundary Waters Canoe Area Wilderness, are predicted to warm faster than others.
So, the Conservancy has used more than a half-century of weather records and the latest climate models to identify “conifer strongholds”—cooler areas where northern conifers can continue to thrive. “We think that many boreal species can persist in favorable sites across the landscape,” said Mark White, a forest ecologist for The Nature Conservancy in Minnesota.
The Conservancy’s two-year planting program is called Conifer Strongholds in a Changing Northwoods Landscape. The work is supported by a grant from the Wildlife Conservation Society through its Climate Adaptation Fund. The fund was created by a grant from the Doris Duke Charitable Foundation.
To help guide the work, the Conservancy has enlisted the help of several other partners, including the Sustainable Forests Education Cooperative at the University of Minnesota, which advises the project.
“The work is very focused on looking at the future of North Shore forests and being proactive about identifying opportunities to conserve native species, to conserve native ecosystems, and in thinking about what we need to do now to maintain forest health and productivity into the future,” says Eli Sagor, Sustainable Forests Education Cooperative manager.
Keeping conifers in the forest will pay dividends. A diverse forest will be more resilient, better able to adjust and remain healthy in a changing climate. Abundant conifers will support a range of wildlife species, from songbirds to mammals. Finally, stands of conifers proclaim northern Minnesota to residents and undergird state pride and tourism. “When you look at northern Minnesota you don’t think of bur oak and red maple,” says Sagor. “You think of the iconic giant red and white pines.”
The decline of conifers has been decades in the making. “The motivation for a lot of work in northeastern Minnesota historically has been the widespread loss of long-lived conifers due to historic logging, limited restoration efforts and over browsing by deer,” says Meredith Cornett, science director for the Conservancy in Minnesota, North Dakota, and South Dakota.
Forests are now dominated by even-aged stands of aspen with fewer pine, spruce, and cedar. Conifer-dependent wildlife, especially some migratory songbirds, have declined as a result.
The solution is more complicated than just planting more conifers. That’s because climate change threatens to raise mean annual temperatures in northeastern Minnesota from 2 degrees to 10 degrees Fahrenheit. The climate is predicted to be wetter overall, but with a drier summer growing season. Such a climate favors a leafy hardwood forest and threatens the prevalence of black spruce, tamarack, red pine, and balsam fir.
Although the Northwoods may see widespread shifts to broad-leafed species like oaks and maples, big conifers aren’t necessarily doomed. Despite a warming climate, Conservancy scientists are convinced conifers can survive—even thrive—in select areas.
So, the Conservancy is planting in “conifer strongholds”—areas of diverse topography (such as hills and wetlands) that have been historically cooler or are warming less rapidly than much of northern Minnesota. The work could be a model for saving conifers in Michigan, Wisconsin and Canada.
Conifer strongholds have three overlapping qualities.
First, they are cooler than surrounding areas or are warming less rapidly. These cool sites may be small—such as north-facing slopes. Or they may be areas of many square miles that have been historically cooler because of the surrounding topography.
Second, these strongholds are diverse geologically and biologically. These areas were identified in the Conservancy’s ongoing work in northeastern Minnesota to identify landscape features that support a diversity of plants and animals in the present, and are expected to support the greatest diversity in the future, even though the species may change over time.
Third, they have “connectivity”—they are surrounded by natural areas that are suitable for the regeneration and spread of conifers.
By combining these qualities, the Conservancy has identified many of the areas where conifers are most likely to flourish in the decades ahead.
The Conservancy has selected dozens of recently harvested federal, state, and county lands for the project. Most sites will receive a mixture of conifer species.
“One of the goals of the project is to really shift people’s thinking about conifer planting practices from single species to mixtures of three or more. Planting for diversity can enhance the adaptability of conifer strongholds,” says Cornett.
The Wildlife Conservation Society chose to support the work on the strength of work the Conservancy has already done to help northern Minnesota forests adapt to a changing climate. “We looked at who we were going to invest in, and The Nature Conservancy has had great success in protecting and restoring Minnesota’s forests,” says Darren Long, program director for the Climate Adaptation Fund.
In addition to the Wildlife Conservation Society, partners in the conifer stronghold project include the U.S. Forest Service, Minnesota Department of Natural Resources, the Minnesota Environmental Fund, Minnesota Outdoor Heritage Fund, Minnesota’s Lake Superior Coastal Program, Conservation Partners Legacy, Scrooby Foundation, Minnesota Moose Habitat Collaborative, the Minnesota Forest Resources Council Northeast Landscape Committee, the Manitou Collaborative, the Northern Institute of Applied Climate Science, and the University of Minnesota.
The Nature Conservancy plans to monitor the planting sites and share information about how they’re doing to inform future efforts to help save Minnesota’s iconic conifers.
Says Cornett, “Focusing our conifer plantings on sites where they’re most likely to survive long term gives us our best chance for success.”