Forested wetland community description and analysis. A pre-emerald ash borer study in an era of global change

Abstract

Trees in 11 900 m2 plots at four headwater wetland sites (Elm Flats, Bonita Swamp, Frog Valley and Bentley) have been identified and measured for 9 years. At Elm Flats trees exhibited a hump-shaped basal area distribution with a high proportion of shade tolerant trees in the larger size classes. This is indicative of a forest that has been subjected to limited anthropomorphic disturbance and possibly retains some old growth characteristics. The older forests also had the richest understory flora. Trees at the other three wetland sites exhibited characteristics indicative of successional swamp forests. Early signs of forest change from the invasive insect, the emerald ash borer, which kills ash (Fraxinus) trees, the most common species in these swamps, are visible in the annual growth increments, tree mortality and canopy cover. This tree census data, in conjunction with the understory species cover data, will be used to assess the impact of non-native species invasions, in particular the emerald ash borer (Agrilus planipennis), and climate change on our forests.