Invasive species are an important driver of habitat change worldwide. One mechanism that may lead to species loss on invaded habitats is the process of "biotic homogenization".  The African grass, Megathyrsus maximus, introduced in Mona Island in the early 1900's, has established extensive stand on that reserve but there is still no information about its effect on its natural communities.   In this study we are testing whether or not the presence of this exotic grass is related to the homogenization of soil meso- and macro fauna and plant communities of Mona Island Reserve.  We set pitfall traps in two invaded sites and two non- invaded sites to characterize arthropod diversity and vegetation communities associated to these traps. The numbers of individuals (per species) are also counted to estimate species diversity for soil and plant communities.  We compared the degree of similarity (in above ground vegetation and soil fauna) of samples collected within invaded sites to that of samples collected within non-invaded areas. 

Results/Conclusions

Levels of heterogeneity were not higher for non-invaded areas.  Instead one of the sampled areas presented unusual levels of heterogeneity for above ground vegetation as well as fauna composition and abundance. While results were not consistent with a hypothesis of biotic homogenization, they suggest that an association between vegetation and soil composition may be possible at the landscape level and not necessarily related to the presence and absence of the exotic grass.