Decay of Fire-Caused snags in Ocala Sand Pine

Abstract

Sand pine (Pinus clausa) scrub is adapted to, and regenerated by, periodic stand-replacement wildfire, which consumes the understory and kills the overstory. The heat of the fire opens the serotinous cones of Ocala sand pine (P. clausa var. clausa), releasing quantities of seed that reestablish the overstory, while the understory regenerates by sprouting or from soil-stored seed. Resource managers attempt to mimic this process by clear cutting and direct seeding, which seems to work quite well. However, this method results in far fewer snags, which may have important functions in the sand pine scrub ecosystem. Because sand pine is a short-lived species with very little heartwood, it is believed that these snags would be a temporary feature of the system, and thus were not that critical. My study tests this assumption by documenting the lift of snags following a stand-replacement fire in sand pine scrub on the Ocala National Forest, Florida. Three stands were burned, one by a prescribed burn in May 1993 and two by natural fire in August 1993. Prior to the fire, there were 520 Ocala sand pine/ha, 96 oaks/ha, and 137 snags/ha. The fire killed all of the sand pine and most of the oaks. Decay proceeded more slowly than expected in the resulting snags. After 2 years 69% retained most of the hark. 27% had lost all bark and most of the limbs, and only 4% had visible sapwood decay. The first snags fell between 12 and 18 months following the tire, but it took 5 years for 50%, of the snags to fall. At the end of 7 years following the fire, 32% of the sand pine snags were still standing. Thus, the snags in sand pine scrub occur as part of the structure of the sand pine ecosystem for much longer than expected. Managers may need to consider more prescribed fire in wilderness areas to generate these snags.

Citation

Outcalt, Kenneth W. 2003. Decay of Fire-Caused snags in Ocala Sand Pine. Pages 50-54 in K.E.M. Galley, R.C. Klinger, and N.G. Sugihara (eds.). Proceedings of Fire Conference 2000: The First National Congress on Fire Ecology, Prevention, and Management. Miscellaneous Publication No. 13. Tall Timbers Research Station. Tallahassee. FL.