A comparison of arborescent vegetation pre- (1983) and post- (2008) outbreak of the invasive species the Asian ambrosia beetle Xyleborus glabratus in a Florida maritime hammock

Background: An outbreak of the invasive species the Asian ambrosia beetle (Xyleborus glabratus) has been devastating populations of Persea borbonia in the southeastern USA. This is the first study to compare pre- and post-outbreak plant diversities in coastal hammock communities. Aims: We compared present-day patterns to those reported before the beetle outbreak. Methods: Vegetation was surveyed in the maritime hammock forest at Little Talbot Island, northeastern Florida, in June 2008. Fifteen 100 m2 quadrats were sampled for density, frequency, and diameter at breast height of arborescent vegetation. Nested within each of the 100 m2 quadrats, an 8 m2 quadrat was sampled for densities of understory taxa. Results: Quercus virginiana remained the most common canopy species when compared with the 1984 data. Juniperus virginiana var. silicicola replaced P. borbonia as the third most common species. Thirty-two percent of adult P. borbonia were dead in 2008. In the understory assemblage, Quercus spp., Sabal palmetto, P. borbonia, Ilex opaca, and I. vomitoria were more abundant in June 2008 than reported in 1984. Conclusions: Changes in structure may be a consequence of the demise of P. borbonia populations. Long-term monitoring of native communities provides a means to understand the effects of exotic pathogens on plant diversity and community structure.