Abundance, rarity and invasion debt among exotic species in a patchy ecosystem
Community assembly through species invasions is a long-term process, for which vital information regarding future trends can be contained in current patterns. Using comparative analyses of native and exotic plant assemblages from meadow patches on islands in British Columbia, Canada, we examined multiple lines of evidence for ‘invasion debt’, a latent expansion of exotic species populations. We show that: (1) short-dispersing species are underrepresented compared to their long-dispersing counterparts in exotic species only; (2) among species that are invasive elsewhere in North America, a greater proportion of long dispersers are common in the study area and a greater proportion of short dispersers are rare; and (3) time since arrival in the study region is positively related to number of occurrences in exotic species. In addition, we show that a suite of exotic species possesses the facility of rapid long-distance dispersal and ability to establish viable populations on even the most isolated and least disturbed patches. While some highly-dispersive exotic species can rapidly colonize new areas, short dispersers appear to exhibit invasion debt, with their potential distributions only being realized in the long term. Removing or even reducing populations of many rapid colonizers could be extremely difficult; however, for species exhibiting patterns most consistent with invasion debt, an opportunity exists for monitoring and removal to help reduce potential competition with native species.
KeywordsDispersal ability Invasion debt Forms of rarity Garry oak ecosystem Invasive species Super-invaders
This work was supported by grants from the Natural Sciences and Engineering Research Council of Canada (NSERC) to MV and PA, NSERC Canada Graduate Scholarships to JRB and PLL, the UBC Biodiversity Centre Postdoctoral Fellowship to WKC, and the UBC Faculty of Forestry. We thank A. MacDougall and two anonymous reviewers for helpful comments on an earlier version of this paper.
- Canadian Climate Change Scenarios Network (CCCSN) (2010) Canadian Climate Change Scenarios Network—Visualization. http://cccsn.ca/?page=scen-viz. Accessed Jan 2011
- Douglas GW, Straley GB, Meidinger DV, Pojar J (1998–2002) Illustrated Flora of British Columbia, 8 vols. BC Ministry of Sustainable Resource Management and BC Ministry of Forests, VictoriaGoogle Scholar
- Fuchs MA (2001) Towards a recovery strategy for garry oak and associated ecosystems in Canada: ecological assessment and literature review. Canadian Wildlife Service, Technical Report EC/GB-00-030Google Scholar
- Leishman MR, Thomson VP, Cook J (2010) Native and exotic invasive plants have fundamentally similar carbon capture strategies. J Ecol 89:3282–3289Google Scholar
- R Development Core Team (2010) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org
- Rabinowitz D (1981) Seven forms of rarity. In: Synge H (ed) The biological aspects of rare plant conservation. Wiley, New York, pp 205–217Google Scholar