We consider Miami-Dade County’s Environmentally Endangered Lands (EEL) network of reserves as a means to conserve rare plant species in urban and suburban forest fragments. In this rapidly urbanizing landscape, pine rockland and hardwood hammock upland forests are at particularly high risk of development. In the absence of fire, broad-leaved trees invade pine rocklands. We examined the number of rare plant species present in reserves based on the site area, ecosystem type and management practices using the EEL database maintained by the county and data bases of plant species inventories collected by the Institute for Regional Conservation.
Results/Conclusions
The EEL program has acquired 25,067 hectares of conservation land through both fee simple purchase and conservation partner agreements. About 99% of the area of the EEL system is located in southern Miami-Dade. Pine rockland forests are primarily in the outer suburbs of the county where fire can be used most effectively for management. Hardwood hammock forests are distributed throughout the county including within the urban core. All 55 EEL forested sites under study contained at least one rare plant species, with a mean of 15.4 (s = 9.3). Species federally designated as endangered, threatened, or candidates for future listing occur at 30 sites. The size of EEL forested sites is positively associated with the richness of rare plant species, but the relationship, while statistically significant, only explains a small amount of variation. Small sites often contained high numbers of rare species per unit area, but presumably at lower population sizes. Fragmentation of pine rocklands is a major conservation concern and the mean distance between fragments was about four kilometers. Sites without public access had greater mean numbers of rare species. Pine rocklands had more rare plant species on average than hardwood hammocks, but fire management makes pine rocklands less appealing than hardwood hammocks for new reserves within the urban core.