Abstract Detail

The North American Coastal Plain: a Global Biodiversity Hotspot

Palmquist, Kyle [1], Peet, Robert [2], Weakley, Alan [2].

Small-scale species richness in longleaf pine savannas: patterns and drivers.

Plant species richness at small scales in the longleaf pine (Pinus palustris L mill.) ecosystem can range from the highest reported for North America at 52 species in 1m² down to just a few or no species present in 1 m². We use three data sets that vary in spatial and temporal extent to examine variation in small-scale species richness across space (within a plot and across plots), time (between a year and across ~ 20 years), and with respect to fire frequency and environmental context. The first data set consists of 915 nested vegetation plots spanning longleaf pine sites from North Carolina through Florida. The second data set consists of 59 plots originally sampled in 1991 and re-sampled in 2009, almost 20 years later. Thirty of those 59 plots were re-sampled again in 2010 to quantify annual temporal dynamics. The last data set consists of plots located in a single species-rich savanna in the Green Swamp Preserve, NC. Plots in the Green Swamp Preserve were sampled annually between 1985-1989, with additional samples in 1994, 2011, and 2012. The most important predictors of plant species richness at small scales were soil moisture and soil texture, with richness highest on moist, silty sites (e.g. savannas) and lowest on xeric sites with coarse sand (e.g. sand barrens). Fire frequency explained additional variation in species richness, albeit less than soil properties. We detected a latitudinal trend in species richness with sites in the southern portion of the range, particularly panhandle FL, having higher species richness than northern sites. We also detected substantial changes in species richness over time, with greater short and long-term changes on silty, frequently burned sites. In addition to fire frequency, long-term fire history influenced changes in species richness over time. Sites that have experienced more frequent fire in the last 20 years relative to the original fire management regime gained species over time, whereas sites with lower frequency lost species. Most of the variation in richness over time is driven by the turnover of infrequent species, which have low abundance, yet constitute the bulk of biodiversity. Lastly, our data set from the Green Swamp Preserve suggests that both short-term and long-term drought events shape small-scale species richness, in addition to fire and environmental context. In summary, small-scale species richness in the longleaf pine ecosystem is structured by multiple ecological processes and varies over space and time.

Broader Impacts:

1 - University of North Carolina at Chapel Hill, Curriculum for the Environment and Ecology, Cb 3275, University of North Carolina, Chapel Hill, NC, 27599-3280, USA
2 - University of North Carolina at Chapel Hill, Biology, Cb 3280, University of North Carolina, Chapel Hill, NC, 27599-3280, USA

Keywords:
longleaf pine savannas
Species richness
prescribed fire
spatial and temporal scale
drought
environmental gradient.

Presentation Type: Symposium or Colloquium Presentation
Session: SY08
Location: Elmwood/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 2:45 PM
Number: SY08004
Abstract ID:564
Candidate for Awards:None