Phenology of grassland plants responds to urbanization

Abstract

Understanding phenological responses of plants to changing temperatures is important because of multiple associated ecological consequences. Cities with their urban heat island can be used as laboratories to study phenological adaptation to climate change. However, previous phenology studies focused on trees and did not disentangle the role of micro-climate and urban structures.We studied reproductive phenology of dry grassland species in response to micro-climate and urbanization in Berlin, Germany. Phenological stages were recorded weekly at the individual plant level for five native grassland species across 30 dry grassland sites along an urbanization and temperature gradient. We estimated 50% onset probabilities for flowering and seed maturation of populations, and analysed variation in onset dates using regression models.Early flowering species significantly advanced flowering phenology with increasing mean air temperature but were little influenced by urbanization. By contrast, late-flowering species showed significant phenological responses to both air temperature and urbanization, possibly because micro-climate was most affected by urbanization in late summer. Surprisingly, not all grassland species showed an advanced phenology with increasing intensity of urbanization.This contradicts observed patterns for urban trees, indicating that phenological shifts in urban areas cannot be generalized from the observation of one growth form or taxonomic group. Growth form appears as a possible determinant of phenological responses. Results suggest that the phenology of dry grassland species may directly respond to the urban heat island, albeit with variable direction and magnitude. This has implications for ecosystem services, shifted allergy seasons, changes of biogeochemical cycles and potential ecological mismatches.

Some like it hot: adaptation to the urban heat island in common dandelion

“…2), on the other hand, as tentative evidence for adaptation. Previous studies have demonstrated shifts in flowering phenology for the overall urban plant community in relation to the UHIE [44][45][46] but have always relied on field observations in whole ecosystems. Such observations cannot distinguish between phenotypic plasticity and genetic divergence.…”

Citizen Science Apps in a Higher Education Botany Course: Data Quality and Learning Effects

“…The dispersion in the plant assemblages between sites was much wider in the students' vegetation collections compared with the expert's. A difference in the species composition between the sites could be expected, for example, to be affected by the different degrees of urbanization per sample location [73,74] or correlations between phenology and microclimatic conditions [75]. However, these factors applied to all groups and could not account for the large difference in dispersion between student and expert surveys, because species composition would not change that dramatically from 2020 to 2021.…”