Ecological and economic values of public trees from the Manitou tree inventory

Abstract

Urban trees are an underappreciated aspect to urban communities and contribute valuable ecosystem services. As of November 2017, the emerald ash borer (Agrilus planipennis), an invasive beetle from Asia had been found in Winnipeg, Manitoba. The beetle is known for its expanding and rapid dispersal rate throughout North America and is expected to continue to extend its range westward throughout the Canadian prairies. A small, farming community in southern Manitoba, Manitou, lies in the potential path of the beetle which will threaten to kill approximately 40% of the total urban tree population in the community. To determine the economic risk that Manitou is facing, an analysis was completed to determine the value and annual contributions of the public urban tree population within Manitou. Three methods are used to determine the annual contributions from the trees and their values. The three methods used are iTree eco v6, the National Tree Benefits Calculator (NTBC) and the Urban Tree Alliance EAB cost calculator. In addition to calculation annual benefits, the Urban Tree Alliance calculator also estimated the annual costs of treating and removing ash trees. Once all the factors were calculated, strategic and tactical management plans for the best course of action were developed to determine what the management of Manitou’s urban tree population should look like for the future. Prioritizing the treatment of larger ash trees (Fraxinus spp) that provide a greater number of economic benefits than smaller ash trees and sequentially removing ash trees that have low economic value will be key actions that the unincorporated Town of Manitou can undertake in the future to maintain a healthy urban forest.