Turning up the heat: fire ecology and climate adaptive silviculture in longleaf pine forests

Abstract

Frequent fire is required to maintain the characteristic structure, function, and high biodiversity of longleaf pine woodlands. Longleaf pine regeneration is exposed to this frequent fire, yet persists as both patches and single tree regeneration. While research has shown that this regeneration within patches alters fuel composition, specific changes of fuel loads, and subsequent alterations of fire behaviour and fire effect is unknown. Results indicate that patches reduce fuel loads and fire effects compared to single tree regeneration, potentially influencing how longleaf pine trees recruit into the overstory through time. This finding may also give insight for future management in an altered climate, where models for the southeastern United States predict increased heat and drought periods over the next decade. This alteration poses a challenge to the application and control of prescribed fires. Understanding how fire may differ in drier climates and a better foundation for understanding spatial variability of fire will be key to managing with prescribed fire in future climates. To address these challenges, managers are considering climate-adaptive silviculture approaches that focus on improving ecosystem resistance or resilience and even transition for novel conditions. Experimental treatments based on these three approaches were applied in longleaf forests of southwest Georgia, where "Resistant" treatments retained drought-resistant longleaf pine, "Resilient" treatments retained longleaf pine and xeric oaks, and "Transition" treatments had the greatest reduction in stand density along with xeric oak underplantings. I evaluated changes in fuel characteristics, fire behavior, and fire effects when burning under dry conditions ([less than] 30 percent RH). I found only minor differences in fuel, fire behavior, and fire effects among treatments, likely from low fuel loads due to frequent prescribed burning. These results indicate that management options in future climates may be flexible in frequently burned longleaf pine forests.