Felling trees within wetlands

Forest managers have nearly stopped harvesting trees within wetlands, because large equipment damages wetlands soils and water quality.  It’s a conservation success story.  Yet- are these forested wetlands healthy?   This project uses a combination of wildlife monitoring and silviculture techniques to find out.

We suggest that the trees in forested wetlands should be young.  Trees in wet areas die often due to beaver activity or flood events that submerge roots for prolonged amounts of time.  Forested wetlands therefore become features of the landscape that create heterogeneity in the forest age structure and gaps in the tree canopy. These gaps provide foraging space for bats and increase productivity for primary producers and consumers. When light is allowed to reach the surface of the water, phytoplankton and periphyton in the wetland grow and serve as food for amphibians and insects within the wetland. Insectivorous bats benefit from the increase in prey biomass that leave the wetlands and reduced clutter in the forest canopy.    

Yet, currently most of the forested wetlands in southern New England contain large old trees.

This project tests whether felling of large trees in forested wetlands enhances wildlife habitat.  We are comparing wildlife use within three control wetlands to three paired wetlands that received silviculture treatments in winter 2019.  A crew, on foot with chainsaws in hand, cut large trees and left them lying to simulate a natural disturbance event. By working during frozen ground conditions, we were careful to not degrade wetland soils. We are now monitoring amphibian, bat, and insect response as bioindicators of wetland health post-treatment.

Dan Wright, MS Student
Chad Rittenhouse, Tracy Rittenhouse, and Tom Worthley