Urban plant ecology patterns and processes: a case study of the flora of the City of Plymouth, Devon, U. K.
AimUsing a large database that has been created over the past 5 years with theRECORDERpackage, presence/absence data for 829 species of vascular plants in the 103 1-km2 squares that cover the city of Plymouth (pop. 243,373) have been analysed by two-way indicator species analysis (TWINSPAN) and canonical correspondence analysis (CCA) to establish the major species assemblages and to examine their spatial distribution across the city in relation to variation in land use.
LocationThe City of Plymouth.
MethodsNine groupings of squares emerged and their distribution was mapped across the city. Interpretation of those groups and their variation in relation to the land use ordination axes showed thatTWINSPANgroups lying along the first axis of variation correlated floristic variation with the process of urban development and the historical evolution of urban structure. The second axis appeared to be related to particular remnant semi-natural habitats within the city that could be regarded as ‘hot-spots’ for survival of many plant species. Species were categorized into four types on the basis of their recency and mode of arrival in the city and by using the historical flora of Plymouth produced by T. R. Archer-Briggs in 1880. Variations in the sources of species in relation to theTWINSPANclassification groups were then examined. A second ordination was also computed; this time with geological, altitudinal and distance variables.TWINSPANgroups were then superimposed on the ordinations using polygons to assist with biogeographical interpretation.
Results and conclusions The results of both the multivariate analyses and distribution of species by source are then discussed in the context of previous research into urban plant ecology, particularly in Central Europe. The problems of inferring process from pattern in this meso-scale study are reviewed and suggestions are made for further research into urban ecology and biogeography in the city.
Keywords: Urban biogeography; adventive and synanthropic species; floristic databases; land use survey; landscape ecology; meso-scale analysis; multivariate analysis –TWINSPAN/CANOCO; plant invasions; urban habitat management and conservation
Document Type: Research Article
Affiliations: 1: Department of Geographical Sciences, University of Plymouth, Drake Circus, Plymouth, Devon, PL4 8AA, U.K. 2: Planning Services, Plymouth City Council, Civic Centre, Plymouth, Devon, England, PL1 2EW, U.K. 3: State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200062, China and Department of Geographical Sciences, University of Plymouth, Devon, PL4 8AA, U.K.
Publication date: November 1, 1999