A comparative assessment of the health condition of recently planted native and non-native soft fruit-bearing and non-soft fruit-bearing tree species in Brampton, Ontario.

With an increasing population and associated development pressures, the City of Brampton (COB) recognizes the need to establish, maintain, and protect urban street trees for the myriad of benefits that they provide. Soft fruit bearing tree species are increasingly being planted due to their unique ecological services that they provide as food sources for wildlife. This study compares the health condition of recently planted native soft fruit-bearing trees to other native and non-native tree species in order to evaluate their performance and better understand their maintenance needs. A 2019 street tree inventory database was used to select tree species and species groupings for these comparisons. The health condition of individual trees was assessed during the inventory and condition ratings were assigned to each tree based on a combination of visual cues. In order to focus on recently planted stock, only trees with a diameter at a breast height (DBH) of less than 10 cm, were included in the analyses. Tree species were grouped for analyses according to their fruiting body characteristics and origin: native soft fruit, native non-soft fruit, non-native soft fruit, and non-native non-soft fruit groups. Sample size was highly variable among species that met these criteria. Differences in the order of magnitude of individual tree species’ sample sizes were therefore used to further divide the groupings into subsets that included tree species with less than 100, between 100 to 1000, and greater than 1000 individual samples. The comparison of median health condition rankings among groups within each subset indicated that native fruit-bearing saplings were in significantly better condition than non-native soft fruit-bearing saplings in subsets with less than 100 samples per species and between 100 to 1000 samples per species, respectively. However, the reverse was true for the subset that included only tree species with greater than 1000 individuals. These conflicting results were attributed to the fact that each subset contained different species within each fruit type and origin-based group; species for which tolerance to urban tree stressors differed. Nevertheless, results of this study infer that many native soft fruit bearing tree species are more resilient to urban stressors than their non-native counterparts, which merits an increase in the proportion of new street tree plantings comprised of these species. For other native soft fruit bearing tree species that are planted in much greater numbers, results suggest that additional maintenance may be required. In combination, both of these recommended actions promise to maximize the ecological services to co-adapted native wildlife that native soft fruit-bearing tree species provide