Land use as a determinate of regional urban forest distribution patterns: A comparative analysis of urban forest study results in the Greater Toronto Area
Municipalities across the Greater Toronto Area (GTA) have completed urban forest studies that quantify the structure and function of this resource. This study seeks to gain insight from a regional analysis of urban forest distribution and structure in the GTA. Specifically, we hypothesize that a regional scale assessment will detect novel structural trends and landscape patterns that exert influence on municipal urban forest governance activities; such patterns may go undetected by analyses conducted at a finer scale. We evaluated the aggregate results of 11 distinct municipal urban forest studies, all of which were completed using i-Tree Eco software and Urban Tree Canopy (UTC) spatial analysis tools developed by the University of Vermont and the USDA Forest Service. This evaluation considered the following variables: leaf area; tree density; diameter-class distribution; tree canopy cover; and species diversity. The analysis examined the relationships between the aforementioned variables and land use classes (e.g. residential, commercial) at the municipal level, and investigated whether the relationships held across local and regional scales.
Preliminary results suggest that across all municipalities there was no significant variation between diameter-class, leaf area, tree density and tree canopy for each common land use class. In other words, the structural characteristics of the urban forest located on residential lands were common to all municipalities. Moderate variation was observed amongst levels of species diversity between common land use classes. However, when results were compared at a municipal scale and land use categories were removed from the analysis, significant variation was observed. Our preliminary results lead us to conclude that land use, regardless of municipal boundaries, may be a significant determinant of the distribution and structure of the urban forest. This suggests that municipalities face common management challenges for which solutions can be informed by a regional monitoring and evaluation framework. For this reason, municipal studies should be designed and implemented in such a way that allows for the aggregation and further analysis of results across a metropolitan region.