An analysis of the vegetation within the FAU Preserve as a basis for management of scrub habitat for Gopherus polyphemus

Background/Question/Methods

Habitat loss and fragmentation is a major problem threatening biodiversity. In Florida, urbanization has caused a decline in the available habitat for its native inhabitants. Scrub habitats have been deemed threatened/endangered habitat and hence are of particular concern. In addition and congruent to the development of natural scrub habitat, many of the remaining suitable scrub habitats have become isolated island ecosystems. Isolated systems lack buffer zones for easy mobility between viable habitats and pose a problem for the perpetuation of the natural processes, like fire. Hence, management of these natural areas is a growing concern for Floridian conservation biologists and ecologists.

Florida Atlantic University (FAU) Boca Raton campus’ Nature Preserve, home for several threatened species—including gopher tortoise (Gopherus polyphemus) and the school’s beloved mascot, the burrowing owl (Athene cunicularia)—is a prime example of mismanaged, fragmented habitat. Lack of proper management has allowed the area to begin succession from a natural scrub into a dense oak hammock overrun by invasive species, such as umbrella trees, rosary pea and earleaf acacia. The process of succession is detrimental for its inhabitants, which are primarily native to scrub habitat. In this project, we characterized specific abiotic and biotic features of the FAU Preserve using on-the-ground vegetation  to measure presence/absence of vegetation types. We used stratified random sampling to conduct soil sampling. This data will assist in identifying the areas in dire need of treatment, as well as the habitat parameters of the species involved.

Results/Conclusions

We compared our vegetation and soil data to recently collected gopher tortoise burrow coordinates in an attempt to detect patterns of resource selection. We found negative correlations between burrow distribution, oak canopy presence, and woody ground vegetation abundance. We found a positive correlation between organic material in the soil and burrow distribution. These tortoises are selecting for areas with minimal shrub and canopy cover and greater herbaceous cover. Vegetation cover throughout the entire preserve was in agreement with literature values of less than 50% total cover for suitable scrub habitat. However, 23% of the preserve was covered by invasive vines. Our data suggests that the habitat is superficially healthy. The significant coverage by invasive vines illustrates potentially rapid degradation if there is no human intervention.