Taxonomic Homogenization of Dorset Woodland
Tuesday 15th July 2014
The Taxonomic Homogenization of Dorset woodland plant communities over 70 years.
Taxonomic Homogenization (TH) is defined as the increasing similarity of the species composition of ecological communities over time. This homogenization represents a form of biodiversity loss and can result from local species turnover. However, in the past, the evidence available to support TH has been limited, due to a lack of suitable historical datasets, and previous analyses have generated contrasting conclusions.
This research, undertaken by Bournemouth University academics Sally Keith and Adrian Newton in collaboration with Natural England and the Centre for Ecology and Hydrology, presents an analysis of woodland patches across Dorset in which they quantified 70 years of change in the composition of vascular plant communities.
The original data used for this investigation was collated by Ronald Good from 1931 to 1939, in which time he surveyed vascular plant species at 7575 sites across Dorset. The investigators selected a sample of patches for potential resurvey by determining which were still extant and had not been replanted, using current maps of woodland habitat provided by the Dorset Environmental Records Centre (DERC). Of the resulting 592 selected patches, a sample of 86 were randomly selected for resurvey, however 21 of these patches were found to be inaccessible so were replaced by new patches. Each patch was surveyed on a day and month as close as possible to the dates employed by Good in the 1930s.
Statistical analysis provided clear evidence of changed composition of the woodland flora over a 70 year period. The patches have increased in similarity in terms of their species composition, which therefore demonstrates Taxonomic Homogenization.
Keith et al concluded that the woodlands have undergone TH without experiencing declines in local diversity or shifts towards novel communities. The analysis of species characteristics suggested that these changes were not driven by non-native species invasions or climate change, but instead reflected reorganisation of the native plant communities in response to eutrophication and increasingly shaded conditions. These analyses provide, to the best of our knowledge, the first direct evidence of TH in the UK and highlight the potential importance of this phenomenon as a contributor to biodiversity loss.
To find out more about Taxonomic Homogenization of Dorsets woodland communities please see the attached .pdf for the full article.