Herbivory by Geese Inhibits Tidal Freshwater Wetland Restoration Success

Abstract

Experimental results from a multi-year exclosure study (2009–2015) demonstrate strong effects of geese on plant cover and species diversity in an urban, restored tidal freshwater wetland. Access by geese inhibited plant establishment and suppressed plant diversity, particularly of annual plant species. Our experimental results demonstrate that the protection of newly restored tidal freshwater wetlands from geese is a make-or-break management activity that will determine the composition and long-term persistence of vegetation at the site. The causal herbivore, in this case, was resident, non-migratory Canada geese (Branta canadensis), which have increased dramatically over the last several decades and had high population densities throughout the study period. These findings suggest that management activities to reduce the population sizes of non-migratory goose populations will support greater wetland plant diversity.