Every summer for 25 years, a team of Michigan State University researchers has walked the same forest trails in the Manistee National Forest, crouching low to count seedlings barely taller than their shoes. What began as a methodical inventory of baby trees has become something far more urgent: a window into which forests will survive as the climate warms.
The work matters because Michigan's forests aren't backdrop scenery—they're economic and ecological anchors. Half the state is forested, supporting more than 90,000 jobs and contributing $27 billion to the economy annually. These same woods filter air and water, prevent erosion, and sustain countless species. But the Great Lakes region has already warmed by 2.3 degrees Fahrenheit since the 1950s, with projections of 6 to 11 degrees more by century's end.
Led by forestry professor Richard Kobe, the research team cataloged nearly 190,000 seedlings across 12 sites spanning 370 square miles of the Manistee National Forest. The researchers walked transects, identifying each seedling less than a year old, noting which species they were and recording the surrounding conditions: air temperature, soil moisture and fertility, how much light filtered through the canopy. Some trees like maples were instantly recognizable by their jagged-edged leaves. Others demanded a more practiced eye.
The pattern that emerged from 25 years of data, now published in Global Change Biology Communications, offers both reassurance and warning. Seedlings of white oak, red oak, black cherry, red maple, and ironwood appear resilient to warmer, wetter conditions ahead. But sugar maple, American beech, white ash, basswood, and black oak—species that have long defined Michigan's forests—may decline as conditions shift beyond what they can tolerate.
Seedling survival is far from guaranteed even when conditions seem favorable. Young trees face what postdoctoral scholar Bailey McNichol describes as a gauntlet. "This is the stage when trees are most at risk from diseases and grazing deer," she notes. Seedlings, with their shallow roots, are particularly vulnerable to warming and drying. Many won't make it past their first years. Yet those that do eventually become the next generation of canopy trees, slowly replacing the giants overhead as they age and die.
Dense tree canopy offers shelter: the researchers found that thick cover above creates cooler, moister conditions that can buffer seedlings from climate extremes. This discovery carries an implicit message—that forest management decisions today about which trees to preserve and encourage could shape which species thrive in Michigan's future.
The work is far from complete. The team plans to track seedling survival beyond that crucial first year, watching which ones advance to the sapling stage and beyond. That longer view is essential because even seedlings that survive early hazards need decades to mature and produce seeds of their own. In that stretch, they remain vulnerable to new diseases, pest outbreaks, or the advance of hungry deer.
Understanding not just where seedlings appear, but why some persist while others fade, will help researchers predict the trajectory of Michigan's forests in the decades and centuries ahead. For a state whose identity is bound up with its woods, that knowledge could prove invaluable.