Valuing the Role of Time in Urban Ecology

Abstract

Cities and towns are complex ecosystems with features that can vary dramatically in space and time. Our knowledge of the spatial structure of urban land and ecological systems is expanding. These systems have been investigated across spatial scales, urban to rural gradients, networks of urban macrosystems, and global megalopolises. However, the temporal dimensions of urban ecosystems – such as those related to ecological cycles and historical legacies – are far less understood and investigated. Here, we outline the main dimensions of time that can shape how events in urban ecosystems unfold, which we categorize as: (i) time flows and duration, (ii) synchrony, lags, and delays, (iii) trends and transitions, (iv) cycles and hysteresis, (v) legacies and priming, (vi) temporal hotspots and hot moments, and (vii) stochastic vs. deterministic processes affecting our ability to forecast the future of cities and the species that live in them. First, we demonstrate the roles of these understudied dimensions by discussing exemplary studies. We then propose key future research directions for investigating how processes over time may regulate the structure and functioning of urban land and biodiversity, as well as its effects on and implications for urban ecology. Our analysis and conceptual framework highlights that several temporal dimensions of urban ecosystems – like those related to temporal hotspots/moments and stochastic vs. deterministic processes – are understudied. This offers important research opportunities to further urban ecology and a comprehensive research agenda valuing the “Urban Chronos” – the change of urban ecosystems through time.

Vehicle pollution is associated with elevated insect damage to street trees

“…Chewing herbivory was lower in 2021 than in 2020 despite lower urban vehicle traffic across the USA in 2020 that has been linked to reduced pollution (Pitiranggon et al, 2022). This pattern that at first glance is contrary to our hypothesis that chewing herbivory is elevated on some trees compared to others because of on-road pollu- of the major drivers of plant-insect herbivore interactions (Ossola et al, 2021).…”

“…While differences in pollution exposure among trees located in different areas may predict levels of herbivory, other factors may be more important in driving how much plants are eaten from year to year. This underscores the need for more long‐term studies on insect herbivory in cities to promote a temporally explicit understanding of the major drivers of plant‐insect herbivore interactions (Ossola et al, 2021).…”

Vehicle pollution is associated with elevated insect damage to street trees

“…While differences in pollution exposure among trees located in different areas may predict levels of herbivory, other factors may be more important in driving how much plants are eaten from year to year. This underscores the need for more long-term studies on insect herbivory in cities to promote a temporally explicit understanding of the major drivers of plant-insect herbivore interactions (Ossola et al, 2021).…”

Urban forest invertebrates: how they shape and respond to the urban environment

“…What can highly fragmented, isolated and dynamic patches of forests in cities reveal with respect to theories on species and community occupancy (Turrini and Knop 2015)? v. What are the effects of city history and historical landscapes (legacy effects) on contemporary invertebrate communities (e.g., Lindborg and Eriksson 2004;du Toit et al 2016 for plants; Ossola et al 2021)? Furthermore, how do invertebrate communities change over time in different urban spatial contexts and are priority effects, i.e., the impacts on a community based on the order or timing of species arrival (Fukami 2015), important in this process?…”