Adapting Black Ash Wetlands to Emerald Ash Borer and Climate Change
Emerald ash borer (EAB) is moving toward the vast black ash wetlands of the Lake States. Black ash is a foundational species in these wetlands because it functions to maintain low water levels during the growing season, allowing trees and plants to thrive. Loss of black ash will profoundly impact this function. Most native tree species that might assume the ecological role of black ash are projected to fare poorly with climate change. Forest Service scientists, with National Forest System, university, and state collaborators, are generating adaptation options for these wetlands using a ground-breaking large-scale experiment on the Chippewa National Forest in Minnesota that simulates EAB mortality in healthy forests and evaluates tree species for their ability to assume the ecology role of black ash. Results demonstrate that loss of black ash dramatically increases water table levels, increases cover of herbaceous plants, and makes tree establishment exceedingly difficult. Approaches that gradually remove black ash mute these changes, allowing new trees to establish. Promising species for replacement of black ash include American elm, swamp white oak, and hackberry, all species that are future-climate adapted. Results from this real-world experiment are being implemented widely by agencies and Tribes in Minnesota and Wisconsin.
Forest Service Partners