Journal article

Road verges as invasion corridors? A spatial hierarchical test in an arid ecosystem

Kalwij J, Milton S, McGeoch M ...see all

Landscape Ecology, vol. 23, issue 4 (2008) pp. 439-451

  • 92

    Readers

    Mendeley users who have this article in their library.
  • 34

    Citations

    Citations of this article.
Sign in to save reference

Abstract

Disturbed habitats are often swiftly colonized by alien plant species. Human inhabited areas may act as sources from which such aliens disperse, while road verges have been suggested as corridors facilitating their dispersal. We therefore hypothesized that (i) houses and urban areas are propagule sources from which aliens disperse, and that (ii) road verges act as corridors for their dispersal. We sampled presence and cover of aliens in 20 plots (6 9 25 m) per road at 5-km intervals for four roads, nested within three localities around cities (n = 240). Plots consisted of three adjacent nested transects. Houses (n = 3,349) were mapped within a 5-km radius from plots using topographical maps. Environmental processes as predictors of alien composition differed across spatial levels. At the broadest scale roadsurface type, soil type, and competition from indigenous plants were the strongest predictors of alien composition. Within localities disturbance-related variables such as distance from dwellings and urban areas were associated with alien composition, but their effect differed between localities. Within roads, density and proximity of houses was related to higher alien species richness. Plot distance from urban areas, however, was not a significant predictor of alien richness or cover at any of the spatial levels, refuting the corridor hypothesis. Verges hosted but did not facilitate the spread of alien species. The scale dependence and multiplicity of mechanisms explaining alien plant communities found here highlight the importance of considering regional climatic gradients, landscape context and road-verge properties themselves when managing verges.

Author-supplied keywords

  • Anthropogenic disturbance
  • Exotics
  • Habitat conduits
  • Invasion
  • Invasive species
  • Karoo
  • Road ecology
  • Seed dispersal
  • South Africa

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Get full text

Authors

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free