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ARS Home » Plains Area » Las Cruces, New Mexico » Range Management Research » Research » Publications at this Location » Publication #131599
Title: FIRE EFFECTS ON RESPROUTING OF SHRUBS IN HEADWATERS OF SOUTHEASTERN LONGLEAF PINE SAVANNAS

Author
item Drewa, Paul
item PLATT, WILLIAM - LOUISIANA STATE UNIV
item MOSER, E. - LOUISIANA STATE UNIV

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2001
Publication Date: 7/1/2002
Citation: DREWA, P.B., PLATT, W.J., MOSER, E.B. FIRE EFFECTS ON RESPROUTING OF SHRUBS IN HEADWATERS OF SOUTHEASTERN LONGLEAF PINE SAVANNAS. ECOLOGY. 2002. V. 83(3). P. 755-767.

Interpretive Summary: Different regrowth responses to the variable nature of fire may result from either fire intensity or location of carbohydrates within a plant at the time of fires. We examined effects of fire season and frequency, geography, habitat and underground organ type on regrowth of shrub stems. Areas containing upslope savanna and downslope seepage bog habitats in Louisiana and Florida were studied. Each site was burned either during the dormant or growing season and reburned 2 years later. Maximum fire temperatures were measured, and the number of shrub stems were censused before and after fires. Collectively, shrubs regrew more stems following dormant rather than growing season fires, regardless of habitat. After repeated dormant season fires, numbers of all shrub stems in seepages of both regions and stem numbers of root crown-bearing shrubs in Florida seepages were greater than those initially and after repeated growing season fires. Shrub regrowth was generally unrelated to fire temperatures supporting the idea that shrub stem regrowth may be more dependent on whether carbohydrates are contained mostly in above- or belowground plant parts at the time of fires. In Florida seepages, the number of new stems following repeated fires decreased with increasing fire temperatures for all shrub species collectively and root crown-bearing shrubs. Dormant season, human-initiated fires over many decades may have resulted in increases of shrubs in longleaf pine savannas, especially seepages. Repeated growing season fires neither increased nor reduced stem numbers of established shrubs. Long-term changes in fire characteristics may produce short-term (<10 yrs), irreversible effects by reintroducing prescribed fires resembling naturally occurring ones during the growing season.

Technical Abstract: Responses to variation in characteristics of fire regimes may be a function of plant physiological status or fire intensity. We examined effects of fire season and frequency, geography, habitat, and underground organ morphology on resprouting of shrubs in upslope savannas and downslope seepages in Louisiana and Florida. Each site contained quadrats located along transects within a 30m x 60m plot, was burned during the dormant or growing season and reburned similarly 2 years later. Maximum fire temperatures were measured and densities of shrub stems censused in quadrats before and after fires. Shrubs collectively resprouted more after dormant rather than growing season fires, regardless of habitat or geographic region. After repeated dormant season fires, collective densities in seepages of both regions and densities of root crown-bearing shrubs in Florida seepages were greater than those initially and after repeated growing season fires. Shrub responses were generally unrelated to fire temperatures, supporting the hypothesis that resprouting of shrubs may be more dependent on their physiological status at the time of fires. There was an inverse relationship between collective and root-crown bearing shrub densities following repeated fires and maximum fire temperatures in Florida seepages. Anthropogenic dormant season fires over many decades may have resulted in increases in shrub densities in longleaf pine savannas, especially seepages. Repeated growing season fires neither increased nor reduced densities of established shrubs. Long-term shifts in characteristics of fire regimes may produce short-term (<10 yrs), irreversible effects by reintroducing prescribed fires resembling naturally occurring ones during the growing season.