Fire Survival of Longleaf Pine (Pinus palustris) Grass Stage Seedlings: The Role of Seedling Size, Root Collar Position, and Resprouting

Abstract

Longleaf pine (Pinus palustris Mill.) forest is a well-known fire-dependent ecosystem. The historical dominance of longleaf pine in the southeast United States has been attributed to its adaptation known as the grass stage, which allows longleaf pine seedlings to survive under a frequent surface fire regime. However, factors affecting post-fire survival of grass stage seedlings are not well understood. In this study, we measured live and dead longleaf pine grass stage seedlings to quantify the role of seedling size, root collar position, and sprouting in seedling survival following a wildfire in the sandhills of South Carolina. We found that fire resulted in almost 50% mortality for longleaf pine grass stage seedlings. Fire survival rate increased with seedling size, but a size threshold for fire tolerance was not supported. Fire survival depended on the position of root collar relative to the mineral soil. Seedlings with protected root collars (i.e., buried in or at the level of mineral soil) experienced <21%, while seedlings with exposed root collars (i.e., elevated above mineral soil) suffered >90% post-fire mortality. Ability to resprout contributed to 45.6% of the total fire survival, with the small seedlings (root collar diameter (RCD) < 7.6 mm) almost exclusively depending on resprouting. Our findings had significant implications for fire management in longleaf pine ecosystems, and the current frequency of prescribed fire in sandhills might need to be lengthened to facilitate longleaf pine natural regeneration.

Gap-Scale Disturbance Patterns and Processes in a Montane Pinus palustris Woodland

“…Thus, under the current disturbance regime, we suggest that P. palustris will remain the dominant species throughout the fire-maintained woodland. Recurring low intensity fires disproportionately kill shoots of fire-sensitive species thereby reducing competition for P. palustris recruitment via gap-scale processes [21,30,85].…”

“…Frequent, low-intensity surface fires help maintain P. palustris dominance and woodland or savanna structures [25,26]. Fires also enhance ground flora cover and diversity [27][28][29][30]. Pinus palustris needles are an important fuel source as the relatively monospecific canopy results in a continuous fuel bed of fine fuels with a high resin content [31].…”

Life Stage and Neighborhood-Dependent Survival of Longleaf Pine after Prescribed Fire

“…Individuals in different life-history stages might vary in their sensitivity to disturbances, often resulting in distinct demographic bottlenecks. High mortality in the early grass stage should be a key determinant of juvenile survival [31]. However, the bolt stage has long been regarded as particularly vulnerable to fire because the apical meristem is exposed and not protected by needles [32][33][34].…”

Calidad de semilla y crecimiento de planta en poblaciones y altitudes de Pinus hartwegii Lindl

“…El crecimiento cespitoso que experimentan las plántulas de P. hartwegii, se puede prolongar por varios años debido al disturbio y a la competencia con especies arbustivas invasivas, que evitan su establecimiento (Jin et al, 2019). Los taxones invasivos son favorecidos ante condiciones de disturbio y del cambio climático, por ello, el rompimiento rápido del estado cespitoso de las plantas es deseable.…”