At the end of April we highlighted the following article, particularly because it questions the timeframe over which we consider 'invasions' to play out: they are probably much longer than many of us have been thinking!
Gilbert B and Levine JM, Plant invasions and extinction debts. Proc Natl Acad Sci U S A 2013, 110(5):1744-9
Our review: F1000Prime.com/718000610#eval793474985
The authors demonstrate experimentally that the native grass populations retreat to refugia of ever smaller size and less favourable conditions, while the habitat between these refugia becomes less hospitable for seed production and establishment through competition with the invasives. Metapopulation models show that the populations become increasingly vulnerable to local extinction with less likelihood of recolonisation because of the distance from other viable seed sources.
Their modelling suggests that these extinctions may take hundreds of years to play out. While this is slow by comparison with direct habitat destruction and the likely impact of climate change, extinction is a long-term consequence of present, profound, and insidious changes to ecosystem processes.