Abstract Detail

The North American Coastal Plain: a Global Biodiversity Hotspot

Platt, William [1], Noss, Reed F [2].

Introduction: The North American Coastal Plain is Global biodiversity hotspot #36.

Biodiversity hotspots, threatened areas where endemic species are concentrated, are priorities for conservation. Globally, 35 hotspots have been designated, 90% of which are in the tropics. Biodiversity in all but one hotspot is strongly associated with geodiversity as a result of large ranges of elevation (2000-8000 m). We now have a solid scientific basis for designating the North American Coastal Plain as Global Biodiversity Hotspot #36. The geological coastal plain extends from 24 to 42o N and from -70 to -99o W along the eastern coast of North America. This subtropical-temperate region extends eastward along the Gulf of Mexico from eastern Tamaulipas, Mexico to the Florida Keys, north along the Atlantic coast to southeastern Massachusetts, USA, and inland within the Mississippi River embayment. The coastal plain is comprised of sedimentary, mostly marine deposits, with little bedrock exposure. Oldest sediments are late Cretaceous, with sediments (mostly sands and clays) progressively younger toward the coast. The maximum elevation range is 250 m, with the large majority of the coastal plain less than 100 m above sea level, making this the least geodiverse hotspot. Nonetheless, the coastal plain is crossed by many rivers, which divide it into physiographic subunits. Mean annual precipitation varies greatly across the region, from 200 mm in Mexico and southern Texas to 1600 mm in eastern Louisiana. The North American geological coastal plain meets three main criteria for biodiversity hotspots. First, it contains 6170 native vascular plant taxa, most of all geological regions in North America. Of these taxa, 1748 (28.3%) are endemic, exceeding the threshold (1500) for a hotspot. Species richness patterns are associated with a ~70 million year evolutionary history and subdivision into units with distinct set of species. Moreover, 50% of the endemism is associated with pine savannas, where a long association with fire has molded the evolution and ecology of the indigenous flora and fauna. Second, the 1133 terrestrial and freshwater vertebrates are similar in species richness to many other hotspots; of these, 18.4% and 32.4% are endemic at species and subspecies levels, respectively. Third, the Coastal Plain has <5% of primary vegetation remaining, placing it among the hotspots most threatened by habitat loss. Losses have resulted primarily from conversion to human uses and fire exclusion, with projected human population growth leading to further land conversion. The presentations in this symposium address many aspects of the biological richness of the North American Coastal Plain.

Broader Impacts:

1 - Louisiana State University, Department of Biological Sciences, 202 LSB, Baton Rouge, LA, 70803, USA, 225/578-6586
2 - University of Central Florida, Department of Biology, 4000 Central Florida Blvd, Orlando, FL, 32816-2368, USA

Keywords:
biodiversity hotspot
North American Coastal Plain
hotspot criteria
pine savanna.

Presentation Type: Symposium or Colloquium Presentation
Session: SY08
Location: Elmwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 1:30 PM
Number: SY08SUM
Abstract ID:379
Candidate for Awards:None