Can Natural Forest Regrowth Keep Pace with Climate Change?
The rules of the game have changed
By American Forests Vice President of Forest Restoration Eric Sprague
Tree planting is often the most recognizable form of reforestation. But forests have their own way to recover after severe wildfires and other incidents that result in tree loss. It’s called natural regeneration. Wind and wildlife carry tree seeds to disturbed areas, where the seeds germinate and eventually grow a new forest. Oaks and some other trees can even resprout from their roots if the trunk dies, the fresh shoots taking advantage of newly opened habitat. Across the U.S., over 90% of forest regrowth happens this way.
There are huge benefits to natural regrowth. It’s cheaper than planting trees, takes less manpower and can result in a more biodiverse forest. Natural regrowth is a key reforestation technique that American Forests and its partners rely on across the country.
In Southern Indiana, for example, we partner with the managers of the Hoosier National Forest to use prescribed fire to restore oak forests, which depend on moderate blazes to create new openings for acorns and weed out competing tree species. In Oregon — where many aspens haven’t established new sprouts in decades — American Forests and our partners fence in key aspen stands to protect new shoots from being eaten by deer and elk herds. And, in California, we don’t plant seedlings if there’s a suitable stand of living trees nearby, which will be able to re-seed the landscape naturally.
However, as the climate crisis intensifies, the rules of the game have changed for natural regeneration. Strategies that trees have honed for millions of years are failing to keep pace. Climate change is fueling unprecedented threats to our forests, including rising temperatures, increased and prolonged drought, extreme weather events, intensifying pest and pathogen activity, and larger and more severe wildfires. These stressors are upending natural regeneration across the country.
Take our national forests. Historically, the U.S. Forest Service could rely on natural regrowth to restore forests after a disturbance. Now, due to climate change-related barriers, natural regrowth in national forests only covers 40% of this need. Foresters have to plant the remaining 60% to ensure that the forest returns.
In the western United States, wildfires now drive the majority of reforestation need — including 80% of the need in national forests. Large, high-severity fires burn so hot and over such a large area that they destroy mature, seed-producing trees and incinerate natural seed banks in the soil. In 2014, for example, the King Fire burned 64,000 acres in the Eldorado National Forest in California. Half of these acres lost all of their trees, and many are now so far away from the surviving forest that they may take generations to regrow on their own, if at all. Similar high-intensity burns are now occurring regularly throughout the west.
Without strategic tree planting and other restoration efforts, burned areas in the Eldorado and across the West will shift to barrens with little vegetation, shrub fields or grasslands. The large-scale loss of forests will have severe repercussions for regional water supplies, carbon capture and storage, wildlife habitat and local economies that rely on jobs in forestry and outdoor recreation.
Human-made climate change has stacked the deck against forests, and planting is one way we can help them beat the odds. Planted seedlings can even have an edge over natural seedlings. Foresters, for example, can grow seedlings from parent trees that show natural resistance to drought or disease. Nursery managers can also grow seedlings in such a way that makes them more resilient to drought. “Plus” seedlings with beneficial genes are then planted in new landscapes, where they’ll eventually spread their genetics via pollen and seeds, boosting the survival chances of the entire forest.
American Forests’ “recipe for climate-resilient reforestation” includes planting species that are better adapted to future climates, with techniques that make them more resilient to the next fire. Over time, American Forests and our partners manage these regrowing landscapes to better withstand drought and other stressors.
The forests of the future may not look like the forests of the past. But by slowing climate change and using climate-informed seed selection, nursery practices, planting and forest management — and the resources to apply these practices on a massive scale — we can help our forests adapt to changing conditions and keep providing communities with forests’ critical natural benefits.