Nonnative old-field species inhabit early-season phenological niches and exhibit unique sensitivity to climate

Native and nonnative plant species can exhibit differences in the timing of their reproductive phenology as well as their phenological sensitivity to climate. These contrasts may influence species’ interactions and the invasion potential of nonnative species; however, a limited number of phenology studies expressly consider phenological mismatches among native and nonnative species over broad spatial or temporal scales. To fill this knowledge gap, we used two complementary approaches: first, we quantified the flowering phenology of native and nonnative plants at five old-field sites across a spatially extensive range of eastern North America. Second, we used herbarium records to compare the sensitivity of flowering and fruiting phenology to climate across a 114-year time period in a subset of common old field species in southwestern Pennsylvania. Across the study region, nonnatives reproduced substantially earlier in the growing season than natives, suggesting that nonnatives occupy a u...