Biological Invasions

, Volume 15, Issue 4, pp 921–930

Tropical paradox: a multi-scale analysis of the invasion paradox within Miami Rock Ridge tropical hardwood hammocks

  • Wesley R. Brooks
  • Julie L. Lockwood
  • Rebecca C. Jordan
Original Paper

DOI: 10.1007/s10530-012-0340-8

Cite this article as:
Brooks, W.R., Lockwood, J.L. & Jordan, R.C. Biol Invasions (2013) 15: 921. doi:10.1007/s10530-012-0340-8

Abstract

The invasion paradox describes the scale dependence of native-exotic richness relationships (NERRs), where NERRs are negative at neighborhood scales and positive at landscape scales. However, a lack of tropical surveys and past failures to isolate potential confounding variables contribute to significant gaps in our understanding of the processes producing these patterns. We surveyed the vascular flora of 13 tropical hardwood hammocks for community characteristics (e.g., native and exotic species richness, vegetative cover) with a hierarchical sampling design. Using model selection, we determined which variables best predicted patterns of exotic species richness at each spatial scale of consideration. We found that native and exotic species richness were positively correlated at neighborhood scales, but negatively correlated at landscape scales. The latter result stands in stark opposition to the patterns published in the literature thus far. We found that natural disturbance history (as approximated by vegetative cover) was positively correlated with exotic species richness at intermediate and landscape scales only. Overall, hammock identity was the most important factor driving exotic species richness patterns at all spatial scales. Hammocks with highly-disturbed hydrologies, brought about by water management, had fewer native species and more exotic species than hammocks with more natural hydrological conditions. Our results are among the first from examination of subtropical communities, and may support the hypothesis that tropical and subtropical communities are subject to more intense biotic interactions. However, given our unique sampling design, our results do not reject the hypothesis that environmental heterogeneity drives the relationship between native and exotic species richness patterns.

Keywords

Exotic Hierarchical modeling Model selection Species richness Vegetative communities 

Supplementary material

10530_2012_340_MOESM1_ESM.doc (362 kb)
Supplementary material 1 (DOC 362 kb)

Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  • Wesley R. Brooks
    • 1
  • Julie L. Lockwood
    • 1
  • Rebecca C. Jordan
    • 1
  1. 1.Department of Ecology, Evolution, and Natural Resources, School of Environmental and Biological SciencesRutgers UniversityNew BrunswickUSA