Weeds in paradise: Thoughts on the invasibility of tropical islands
By J. Denslow. 2003
239 citations recorded by the source corpus.
Tropical island ecosystems appear to be especially vulnerable to invasive species as indicated by the often high numbers and percentages of exotic species on oceanic and continental islands. Here I reexamine hypotheses offered to account for the apparently high invasibility of tropical islands and suggest a simple synthesis based on resource availability, propagule supply, and relative competitive abilities of exotic and island species. This review suggests that fundamentally two interacting processes-high net resource availability and poor ability of native species to preempt those resources-make island communities vulnerable to the establishment and spread of alien species. In addition, historically high rates of introduction have provided opportunity in the form of a diverse and abundant propagule rain of exotic species. The combination produces a scenario that is not an optimistic one for island ecosystems. It suggests that these native ecosystems on islands are particularly vulnerable to naturalizing exotics growing on their borders, and that while disturbance from a variety of causes, including pigs, fire, grazing, and natural dieback of the canopy dominants, increases the opportunities for exotic incursions, even intact forests are not immune. Unless these forests are aggressively managed and alien propagule pressure reduced, they will be highly modified by expanding exotic plant populations. Tropical islands are an effective early warning system of the impacts that successive waves of exotic species invasions may cause to isolated ecosystems. As mainland natural areas become fragmented, degraded and depauperate, they acquire many of the ecological attributes of islands, including limited habitat area, missing functional groups, declining species diversity, and disturbed habitats. A better understanding of invasions on islands may improve our attempts to protect both mainland and island ecosystems from the impacts of exotic species.
Subfields: Ecology, Nature and Landscape Conservation
View Paper: https://www.semanticscholar.org/paper/baa5918da0f0a147d66bdae3894e736d4b130d7d
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Citations in the corpus
- Contrasting patterns in the invasions of European terrestrial and freshwater habitats by alien plants, insects and vertebrates (2010, background): “…is thought to be due to the lower resistance of species-poor communities to invaders and the effect of smaller native species pools on islands (e.g. Denslow, 2003; Hulme, 2004; Herben, 2005) resulting from isolation, or a more intensive effect of human-related environmental driving forces compared…”
- Invasive Exotic Plants in the Tropical Pacific Islands: Patterns of Diversity (2009, background): “…for high numbers of non-native plant species on islands, including high habitat diversity, disharmonic floras, low biotic resistance, high resource availability, and mild climates (Loope & Mueller-Dombois 1989, D’Antonio & Dudley 1995, Kitayama & Itoh 1999, Cox & Elmqvist 2000, Denslow 2003).”
- A global comparison of plant invasions on oceanic islands (2010, background): “More generally, it has been suggested that invasive plants may profit from empty niche opportunities not filled by the native and established non-native flora (Meyer, 1998; Denslow, 2003; Mueller-Dombois, 2008; Kueffer et al., 2009); and these may differ in particular between small and isolated isla”
- Hurricane disturbance accelerates invasion by the alien tree Pittosporum undulatum in Jamaican montane rain forests (2005, background): “This offers support for Denslow’s (2003) suggestion that compared with continental forests, lower diversity forests on oceanic islands have poor resistance to the establishment of new individuals of alien species.”
- Conservation of oceanic island floras: present and future global challenges. (2010, background): “Denslow (2003) reported that the introduced Rubus ellipticus is competitively superior to the Hawaiian native R. hawaiiensis.”
- Plant invasions: merging the concepts of species invasiveness and community invasibility (2006, background): “…confirming among other things that islands are more invasible than mainland (Darwin, 1845, cited by Cassey, 2003; Rejmánek, 1996; Lonsdale, 1999; Denslow, 2003), temperate agricultural or urban sites are the most invasible biomes, and that the New World is more invasible than Old World (but…”
- Limited native plant regeneration in novel, exotic-dominated forests on Hawai’i (2008, background): “…having evolved in extreme isolation, is much more highly endemic than the Puerto Rican flora, a fact that has likely contributed to both the number of successful introductions on Hawai’i and the apparent competitive superiority of many exotic species (Egler, 1942, Denslow, 2003, Woodcock, 2003).”
- The Fire-Lantana Cycle Hypothesis in Indian Forests (2005, background): “The former is characterised by an ample supply of well-dispersed propagules to opportunistically take advantage of disturbances; the latter by the ability to compete effectively with native species for available resources (see also Denslow 2003).”
- Invasive alien species on islands: impacts, distribution, interactions and management (2017, background): “Thus, it is now generally considered that the greater number of IASs on islands per unit of area reflects higher propagule pressure to islands compared to continents (Denslow 2003).”