Taxonomic homogenization of woodland plant communities over 70 years

Abstract

Taxonomic homogenization (TH) is the increasing similarity of the species composition of ecological communities over time. Such homogenization represents a form of biodiversity loss and can result from local species turnover. Evidence for TH is limited, reflecting a lack of suitable historical datasets, and previous analyses have generated contrasting conclusions. We present an analysis of woodland patches across a southern English county (Dorset) in which we quantified 70 years of change in the composition of vascular plant communities. We tested the hypotheses that over this time patches decreased in species richness, homogenized, or shifted towards novel communities. Although mean species richness at the patch scale did not change, we found increased similarity in species composition among woodlands over time. We concluded that the woodlands have undergone TH without experiencing declines in local diversity or shifts towards novel communities. Analysis of species characteristics suggested that these changes were not driven by non-native species invasions or climate change, but instead reflected reorganization of the native plant communities in response to eutrophication and increasingly shaded conditions. These analyses provide, to 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.

Biotic homogenization and differentiation in weed vegetation over the last 70 years

“…A similar pattern has been reported for weed vegetation [36] and woodlands [5], although they are a more stable environment. The increase in eutrophication leads to an increased proportion of generalists.…”

Butterfly abundance in a warming climate: patterns in space and time are not congruent

“…Our models predict that climate warming will lead to the increased domination of butterfly communities by a few generalist species, providing another example of biotic homogenisation (Keith et al 2009, Pino et al 2009, Ekroos et al 2010). …”

Distinguishing between turnover and nestedness in the quantification of biotic homogenization

“…Previous studies have for instance found clear evidence for the importance of changes in forest management or canopy succession (e.g., Kirby and Thomas 2000;Van Calster et al 2008;Rogers et al 2008;Baeten et al 2009;Keith et al 2009), changed deer abundances (e.g., Kirby and Thomas 2000;Rooney et al 2004;Taverna et al 2005), increased atmospheric deposition of acidifying and eutrophying pollutants (e.g., Lameire et al 2000;Van Calster et al 2007;Baeten et al 2009;Keith et al 2009) or past habitat loss and fragmentation (e.g., Rogers et al 2009). For Lady Park Wood, canopy succession and deer (over)abundance are probably the main drivers.…”