Abstract: Canada recently hosted the COP15 Biodiversity talks, collectively agreeing to reduce human-induced extinction, restore degraded ecosystems, and sustainably manage biodiversity. But efforts to conserve, restore, and manage biodiversity are complicated by increasing land-use change, particularly the rapidly increasing urban landcover worldwide. This project seeks to understand the influence of land-use composition, particularly urbanization, on biodiversity in one of Canada’s fastest-growing urban centres; the Greater Toronto Area (GTA). Building on previous studies of the plant functional trait communities and ecosystem service delivery in the GTA, this study focuses on the effects of landscape composition and configuration on biodiversity metrics and native species abundance and discussing the implications for biodiversity management.
We integrate spatial data with vegetation monitoring data provided by the Credit Valley and Toronto Regional conservation authorities for wetland, riparian, and forest plots. Using a combination of linear and geographically weighted regressions, we test if plant biodiversity and species abundance—specifically non-native species abundance—are explained by land-use composition (500m and 1km scale) and/or distance from an urban centre. We then compliment this analysis by clustering sample plots (K-means clustering into primarily urban, agricultural, and naturalized sample plots) to test the similarities and differences of plant communities between site ‘types’. Additionally, we investigate whether urban areas contain increased abundance of non-native species. We hypothesize that biodiversity will increase with cover of natural areas and distance from urban centres, with this response being consistent across habitat types. We also anticipate that, in areas where diversity may stay consistent between urban and natural areas, the abundance of non-native species will increase with total cover of urban landcover and decrease with distance from urban centres.
Preliminary analysis initially confirms our hypothesis, as alpha diversity and species abundance measures were significantly correlated with landscape composition, and the ratio of non-native species to native species was significantly correlated with urban land cover at multiple scales. Additionally, as the scale increased there was an increase in significant relationships (both more significant relationships and lower p-values). Further investigation could provide essential information about the best scales at which to monitor biodiversity and to implement management and conservation strategies. This also suggests that the impact of non-native species should be considered at the landscape scale, rather than site-specific scales. More detailed analysis could indicate specific ways that different land-use compositions warrant more ‘site specific’ management based on landcover and habitat type to maximize benefits to biodiversity conservation efforts.
