What fire frequency is appropriate for shortleaf pine regeneration and survival

—Shortleaf pine community restoration requires an answer to the question, “What fi re frequency is appropriate for shortleaf pine regeneration and survival? ” The answer to this question is one of the most critical to successful restoration through fi re management. We used three sources of information from Missouri to determine appropriate burning frequencies: a 400-yr historic shortleaf pine growth and fi re-scar database, fi re effects data from prescribed burning sites, and a vegetation dynamics prediction model that is widely used for characterizing fi re regimes. The historic shortleaf pine and fi re scar database provides actual past scenarios of regeneration dates, growth, survival, and associated fi re events. Shortleaf pine regeneration established most commonly during the 4 years following fi re events and generally decreased in abundance with years since fi re. Surviving seedlings were those that were not fi re scarred the year following establishment, and the mean number of years to a subsequent fi re was about 7 years. Fire effects data from prescribed burn sites revealed that both hardwood and pine regeneration showed substantially increased mortality after four consecutive dormant season burns, but oak and hickory species were more likely to survive frequent fi re. Mortality of advance regeneration was generally low in all hardwood species after one burn, while shortleaf pine seedlings had high mortality rates. The model showed 8 to 15 yr intervals are likely best for balancing both continual regeneration and recruitment. Model prediction runs for 500 years showed a signifi cantly decreased pine component in the absence of burning. Conversely, long-term frequent burning (1to 3-yr intervals) resulted in abundant regeneration, but poor survival and ultimately decreased abundance in midand late-successional forests. In summary, all three sources support the effi cacy of frequent burning (1 to 4 yrs) in promoting pine regeneration, but survival and continued recruitment require longer fi re intervals (8 to 15 yrs). Fire management prescriptions that incorporate both frequent burning and longer intervals will likely provide for the most long-term regeneration and recruitment success. 1Senior Research Specialist (MCS), Department of Forestry, University of Missouri-Columbia, Columbia, MO 65211; Research Associate Professor (RPG), Department of Forestry, University of Missouri-Columbia, Columbia, MO 65211; and Research Forester (DCD), U.S. Forest Service, Northern Research Station, Columbia, MO 65211. MCS is corresponding author: to contact, call (573)-8828841 or email at stambaughm@missouri.edu INTRODUCTION It is widely recognized that fi re is critical to shortleaf pine forest ecosystems (Cooper 1989, Bukenhofer and others 1994, Masters and others 1996, Stanturf and others 2002, Rimer 2003, USDA 2003). However, shortleaf pine restoration through fi re management begs the answers to questions such as “What fi re frequency is appropriate for shortleaf pine regeneration and survival? ” Much of the information about shortleaf pine and fi re comes from fi eld trials and lies with experienced individuals while relatively little is published about experimental fi ndings. Because of the dynamic conditions of fi re events (due to fuels, weather and climate, vegetation, topography, burning technique, etc.), it is diffi cult to relate single experimental results to the management of large and different forested landscapes. The historic role of fi re within shortleaf pine communities of the Ozark Highlands has been well established and described (Guyette and others 2002, Guyette and others 2006) (Fig. 1). The pre-Euro-American dominance of shortleaf pine in the region was negatively related to historic mean fi re intervals (Batek and others 1999). Wildfi res likely maintained many of the presettlement shortleaf pine communities and, though at times severe, were predominantly non-stand-replacing surface fi res resulting from anthropogenic ignitions. Mixed severity fi res resulting in small stand-replacement events likely occurred within the region about every 20 years (Guyette and others 2006). Today, wildfi res typically consist of small-scale, low severity surface fi res (Westin 1992, Stambaugh and others in press) that are rarely stand-replacing events.