Wade A. Wall ERDC-CERL Janet B. Gray Fort Bragg Endangered Species Branch Matthew G. Hohmann ERDC-CERL NMFWA Annual Meeting 14 March 2012 Atlanta, GA Courtesy Beth Evans

 Historical (1500 A.D) estimates: 1-3 years  Fire suppression, buildup of fuel loads  Prescribed fire ~ 20 years (red cockaded woodpecker  Benefits: wildfire reduction, improved habitat, species management

 Reduced competition  Increased survivorship  Increased productivity  Increased flowering  Increased germination  Reduced seed predation

 50% of rare plant species in FL exhibited positive responses (Slapcinsky et al. 2010) 9 of 18 no response  Climatic uniqueness of Florida? Fire history centerforplantconservation.org

 Determine effects of fire on study species Identify “optimal” fire return interval Model population dynamics  Interpret results in light of the climatic history of the Sandhills region.

 Astragalus michauxii Sandhills milkvetch “Pea swales” xeric sandhill scrub Fort Bragg, Gordon  Pyxidanthera brevifolia Sandhills pyxie moss xeric sandhill scrub Fort Bragg, Dix  Both species SAR, FSC

 A. michauxii Surveyed 87 pops. Tagged all identified individuals 2007 Measured survivorship, growth, reproduction  stem height  Counted viable seeds in 400 fruits  P. brevifolia Selected 24 pops. (out of 277 total pops.) Tagged 1000 individuals Measured survivorship, growth, reproduction  Major, minor axis  Estimated percent coverage  Fruit production

 Generalized linear models to analyze survivorship, growth, and reproduction.  Matrix modeling to project population growth through time t smalllarge t + 1 small large N = N ( ) = 15 (5+40) = 45

Short-term effect of fire on mortality: A. michauxii

Short-term effect of fire on mortality: P. brevifolia

Fire reduces fruit production in A. michauxii

Fire reduces fruit production in P. brevifolia

Regeneration following fire size is dependent in A. michauxii

Regeneration following fire is size dependent in P. brevifolia

Projected population growth rate lower under annual burning

 Vegetation differences during last ice age Spruce forest Exposed soil, reduced biomass  Lower competition  Adapted to colder environment?  Fire replaced climate as limiting factor Necessary for competition removal A. michauxii and P. brevifolia may not be as adapted to fire as other species. rst.gsfc.nasa.gov

 Short term consequences of fire Increases mortality Decreases seed production No increase in seedling recruitment Slow regrowth?  Long term consequences of fire Reduction of competition, woody growth Necessary for long term population persistence  “Caught between a rock and a hard place”  Current fire return interval adequate

Distribution of Astragalus michauxii and Pyxidanthera brevifolia across Fort Bragg Military Reservation

 Rare taxa may have different responses to fire Different histories  Lack of information on many plant species in fire- dependent ecosystems  412 plant SAR ~318 dependent on or influenced by fire Few have been studied

Fort Bragg Military Installation Fort Bragg Endangered Species Branch ERDC-CERL North Carolina State University