Taxonomic diversity, Pest Vulnerability, and Carbon Storage of the Urban Forest in Winnipeg, Manitoba, Canada

Abstract

Canadian prairie cities face a number of challenges when managing urban forests, one of which is reduced tree diversity due to more severe climate constraints to tree survival. This thesis reports on diversity and carbon storage for the city of Winnipeg, Manitoba, Canada. Approximately 24,500 trees were surveyed and measured across 77 Winnipeg neighborhoods, including trees on private lots, which had not been previously reported for the city. Using these data, I evaluated tree species diversity measures for city neighborhoods and compared diversity measures between trees on public and private property. Private properties exhibited higher tree diversity and better health status across all metrics. I also adapted the Pest Vulnerability Matrix (Lacan & McBride, 2008) to environmental conditions found in the city of Winnipeg to identify pests with the most potential to impact city forests and neighborhoods as well as areas most at risk of new pest invasion. Exploring carbon storage in the city, I used methods developed by Wayson et al. (2015) to create prediction intervals (a measure of reliability for the prediction of an observation) around biomass equations used by city foresters. I then estimated carbon storage in residential areas across the city. I found 58% of carbon stored in trees surveyed was in American elm (Ulmus americana), and no other tree species in the survey had an equivalent amount of stored carbon (based on mean DBH). This research incorporates the first large scale private tree inventory within Winnipeg, providing a more comprehensive assessment of tree species diversity and carbon storage values across the city. This study will allow urban forest managers to have a clearer understanding of the existing tree inventory and implications for future urban forest management activities to protect and increase the city’s urban forest resource.