PS 46-206 - Does urbanization induce phenological mismatches in orchard pollinators?

Abstract: Many urban areas are considered food deserts as they lack resources that provide nutritional food options. Urban orchards can serve as an alternative to traditional grocery stores and provide healthy food to residents that may otherwise go without. The success of urban orchards depends on synchronized plant and pollinator phenology that result in bee emergence times that align with plant flowering periods. However, rapid urbanization experienced in many of these food deserts can have harmful effects on local ecology. Disproportionately higher urban temperatures may be detrimental to phenological matching of plants and pollinators if air and soil temperatures are not warming at similar rates. If phenoevents of these species become asynchronous, it could negatively impact pollination services required for optimal fruit set. This study documented potential phenological mismatching along an urbanization gradient using orchard sites in urban, suburban, and exurban areas. In the spring of 2022, tree and pollinator phenology data were collected from ten sites. Pollinator activity schedules were obtained through specimen collection via netting of foraging insects as well as video recordings of insect visits to individual trees. Flowering phenology data was collected in two ways: floral counts on randomly selected tree branches and site-level counts of number of flowering fruit trees every 4.9 days, on average. Our results indicate that there are no significant differences between urban categories and phenological mismatches among fruit trees and their pollinators. Indeed, neither the plants nor their pollinators exhibited different phenological patterns (i.e., day of first flowering did not differ) within the different urbanization landscapes. The largest variation in mismatch occurred in exurban environments (0-44 days), whereas the timing of first flower in urban areas was most consistent (0-1 days). Lower variation in phenological mismatch suggests that urban environments may exhibit more consistent temperature regimes across sites relative to exurban and suburban sites. However, we are unable to test this with the current dataset. Future studies are needed to determine if this trend is seen in other urbanized landscapes and whether other landscape features, such as patchiness of wooded areas, may play a role in the larger variation in phenological mismatches seen here.