22. Urbanisation and plant functional traits

First meeting was held 19-23 February 2007 in Melbourne. Second meeting 10-14 December 2007 in Melbourne. Third meeting held 15-19 December, 2008 in Melbourne.

PARTICIPANTS Leader Nick Williams, University of Melbourne Mick McCarthy, Australian Research Centre for Urban Ecology Mark McDonnell, Australian Research Centre for Urban Ecology Peter Vesk, University of Melbourne Richard Duncan, Lincoln University, New Zealand Richard Corlett, Hong Kong University Mark Schwartz, University of California, Davis Steven Clemants, Brooklyn Botanic Gardens Ken Thompson, University of Sheffield Amy Hahs, Australian Research Centre for Urban Ecology, Melbourne Briony Norton, University of Melbourne Participants at second meeting: Williams, Schwartz, Thompson, Duncan, Clemants, McCarthy, Norton, Vesk, McDonnell Participants at third meeting: Williams, Duncan, McCarthy, Norton, Vesk, McDonnell, Hahs, Corlett

Feb 07> Dec 08>

We continue to make good progress on our investigation of traits that may make plants susceptible to extinction in urban areas. We have analysed the data from our 11 cities and found a few general trends and many individual cases. A manuscript is in preparation. We are also close to completing a paper investigating the correlations between the number of extinctions in 21 cities around the world and the amount of native vegetation and city history. After 3 meetings the working group has published the following papers

Thompson, K., and M. A. McCarthy. 2008. Traits of British alien and native urban plants. Journal of Ecology 96:853-859.

Williams, N. S. G., M. W. Schwartz, P. A. Vesk, M. A. McCarthy, A. K. Hahs, S. E. Clemants, R. T. Corlett, R. P. Duncan, B. A. Norton, K. Thompson, and M. J. McDonnell. 2009. A conceptual framework for predicting the effects of urban environments on floras. Journal of Ecology 97:4-9.

The 2nd paper is dedicated to the memory of Steve Clements, an excellent plant taxonomist, urban ecologist, valued member of the group and friend who died suddenly just before it was published.

Background
Urbanisation is an important impact on ecosystems around the world. Urbanisation can be considered both as an ecological gradient and as a characteristic suite of disturbances that homogenises biota. In addition, urban habitats around the world are structurally similar and consistent changes in physical and biological parameters are exhibited along urbanisation gradients. These features suggest that a plant functional trait framework could be productively applied to urban floras. Typical questions include

• Are there trends in the distribution of functional traits, of urban floras with geographic location (latitude, Europe vs “New World”), extent of urbanisation, age of city, population density etc?
• Is there a suite of functional traits that advantage or disadvantage plant species in urban landscapes?
• What are the processes that are causing species with particular plant traits to increase or decrease in urban areas?

The first meeting of this working group gathered together plant species and plant trait data for 11 urban areas (Melbourne, Adelaide, Auckland, Singapore, Hong Kong, Sheffield, San Francisco, Los Angeles, San Diego, Chicago, New York). Some further work is needed to improve the match of trait data across the different cities, but some analysis was possible immediately. It is likely that papers will emerge both on the observed characteristics of urban floras, and also on the conceptual issues in thinking about urbanization.

The second meeting of WG22 was in Melbourne in December 2007. The working group produced two manuscripts which have been submitted to journals and made substantial progress on two others. The first paper is an analysis of a vegetation dataset along a British urban-rural gradient to compare the traits of species defined by their urbanity (proportion of urban land cover in the 1-km grid squares) and frequency in highly urban grid squares. The second details a conceptual framework describing how plant traits interact with the filters involved in the urbanisation process to create urban floras. We continued to make progress on our global analysis of the traits that may contribute to plant extinction in cities and will be ready to run the analysis once some data inconsistencies are cleaned up. We have also put together a dataset that should allow us to investigate the influence of city characteristics (ie. age, population density, % green space) on plant extinctions in urban areas.

Last updated January 2009