Changes in urban forest canopy quality as measured using landscape pattern indices

Authors: Clara Greig*, Urban Forest Research and Ecological Disturbance (UFRED) Group, Ryerson University | Geography and Environmental Studies, Wilfrid Laurier University, Andrew A Millward, Urban Forest Research and Ecological Disturbance (UFRED) Group, Ryerson University
Topics: Biogeography, Remote Sensing, Environment
Keywords: urban forest, canopy quality, change, pattern indices, fragmentation
Session Type: Paper
Day: 4/4/2019
Start / End Time: 3:05 PM / 4:45 PM
Room: Marshall South, Marriott, Mezzanine Level
Presentation File: No File Uploaded

Urban forests provide a vast array of ecosystem services, with function depending upon the spatial structure and arrangement of existing forest patches. Urban landscapes are known to be highly fragmented, thus exposing forest patches to substantial disturbances, consequently reducing ecosystem function. With increasing pressure on remaining urban forests, it is necessary to explore patterns of change in canopy quality across the urban landscape to identify vulnerable regions and drivers of fragmentation. In this paper, we explore landscape pattern of three canopy density classes (low-density, high-density and contiguous), in Toronto’s urban forest by performing a landscape pattern analysis at three different scales (citywide, ward and neighbourhood), for the years 1985 and 2005. Using the calculated landscape pattern indices, we subsequently performed a change detection and applied a local Moran’s I to locate clusters of canopy gain/loss. Over these two decades, citywide statistics revealed that the low-density canopy proportion of the landscape increased by 1.1% (20.5% to 21.6%), while high-density and contiguous canopy proportion landscape has decreased by 0.5%, (18.1% to 17.6%) and by 1% (7.0% to 6.0%), respectively. Ward and neighbourhood-level landscape pattern analysis revealed that low-density canopy proportion landscape, number of patches and mean patch area has increased in areas where contiguous canopy has decreased. Although the proportion of contiguous canopy has decreased, remaining patches have increased in mean area in parks and ravines. Finally, high-density canopy increased in number of patches and decreased in mean patch area across the city, suggesting fragmentation of this canopy type.

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