Fire-maintained longleaf pine vegetation of the southeastern United States: A case study in implementation of the US National Vegetation Classification standards

The ESA Vegetation Classification Panel and the US FGDC Vegetation Subcommittee have jointly developed new standards for the floristic levels of the US National Vegetation Classification (VNC).  Full implementation of these standards requires that (1) type descriptions be based on publicly available plot data, (2) descriptions of types incorporate geographic variation, and (3) the recognized types completely tile the universe of variation. The challenges of transition to the new standards have not previously been addressed through demonstration projects. I examined and revised the existing classification for fire-maintained longleaf pine vegetation of the southeastern US as a demonstration project. Fire-maintained longleaf pine vegetation was at one time the dominant vegetation of the Coastal Plain and adjacent areas from southeastern Virginia, south through much of Florida and west into east Texas. This vegetation is often species rich and the region is a center of endemism resulting in considerable floristic turnover. The draft NVC of NatureServe contained 140 longleaf associations but lacked quantitative descriptions. I used in excess of 900 detailed vegetation plots distributed across the eastern two thirds of the range of longleaf to evaluate, revise, and describe associations for the NVC. This exercise resulted in recognition of 132 associations of which 23 were retained unchanged but were for the first time quantitatively described, 45 were retained intact for lack of plot data, 42 types recognized and described had complex relationships with one or more previous associations, and 25 entirely new associations were created.  I anticipate that full quantitative documentation and review should lead to similar levels of revision of the NVC for other regions.