BRANTA — Veronica Mendez Aragon
Spatial and temporal variation in the functional diversity of non-breeding wader communities across British estuaries
Institution: University of East Anglia, UK
Supervisors: Richard G. Davies, Jennifer A. Gill, Niall H.K. Burton
Details: PhD 2012 (Completed)
Address: British Trust for Ornithology, The Nunnery, Thetford IP24 2PU, UK (Apr 2013) Email
Subject Keywords: Community and population dynamics, functional diversity, coastal wetlands, waterbirds, conservation
Species Keywords: Waders
Many wader species depend on estuarine ecosystems during the non-breeding season. However, many estuaries around the world are under intense pressure from human impacts, greatly influencing the composition of wintering wader communities. Changes in communities have been documented using species richness and evenness. However, these measures do not account for the fact that coexisting species differ widely in the level of distinctness of the ecological roles they fulfil. Considering whole communities in terms of the range of traits, the ecological roles represented by each species and the mechanisms that regulate community assembly, is a more powerful method of understanding variation in community composition. In this thesis, national-scale datasets are used to explore spatial and temporal variation in the functional diversity (FD) of wintering wader communities across UK estuaries. Using null model analysis, I show that wintering wader communities, overall, are more functionally similar than expected from a random community with equivalent number of species, suggesting that environmental conditions have the strongest influence on structuring these communities. The relative influence of structuring processes appears to be changing through time, as communities are becoming more functionally diverse than expected by chance. Using different environmental datasets, I explore the spatial and temporal variation in FD and identify potential drivers. Furthermore, I investigate which species are more likely to contribute to changes in FD. Using data from WeBS Low Tide Counts, I go on to show a tendency for functionally similar species to aggregate within the intertidal area. The thesis findings emphasize the likely importance of environmental factors for wader community assembly. Understanding the processes underlying community assembly can help in understanding community responses to environmental change and improve conservation and management plans.
Mendez, V., Gill, J. A., Burton, N. H. K., Austin, G. E., Petchey, O. L. and Davies, R. G. (2012) Functional diversity across space and time: trends in wader communities on British estuaries. Diversity and Distributions 18: 356-365.