Lightning, fire and longleaf pine: Using natural disturbance to guide management

Abstract

The importance of lightning as an ignition source for the fire adapted longleaf pine (Pinus palustris) ecosystem is widely recognized. Lightning also impacts this system on a smaller scale by causing individual tree mortality. The objective of this study was to determine mortality due to lightning and other agents in longleaf stands on the Ocala National Forest in central Florida and to quantify lightning ignited fire. Mortality from lightning was also tracked in longleaf stands on the Savannah River Site in South Carolina. Lightning killed more trees than any other agent with a mean mortality of nearly 1 tree/3 ha/yr in Florida and 1 tree/8 ha/yr in South Carolina. The probability of a tree being struck by lightning increased as a function of tree height at both sites, i.e. lightning preferentially removed the largest trees from the stand. In addition lightning strikes were clumped within stands, sometimes killed multiple trees with a single strike, and often hit trees on the edge of existing gaps. The combination of these processes means gaps suitable for regeneration within longleaf stands are created quite rapidly. This information provides guidelines for the development of selection harvest systems based on this natural disturbance. Although lightning activity was greatest during the summer months in Florida and most fires occurred in June, the probability of a strike causing a fire was highest in February to May. Published by Elsevier B.V.

Influence of reproduction cutting methods on structure, growth and regeneration of longleaf pine forests in flatwoods and uplands

“…In the absence of fire, neither selection system disturbed these stands sufficiently to impede the long-term rise of shrubs (Brockway and Outcalt, 2015). This finding underscores the importance of frequent prescribed burning for maintaining longleaf pine forests (Brockway and Lewis, 1997;Brockway et al, 2005b;Outcalt, 2008;Outcalt and Brockway, 2010).…”

“…Two additional cycles of prescribed fire decreased oak cover, thus discouraging these young hardwoods from ascending to the canopy and gaining dominance in the forest (Glitzenstein et al, 1995;Kush et al, 1999;Provencher et al, 2001). As highly-resilient disturbancedependent ecosystems (Stanturf et al, 2007;Outcalt, 2008), longleaf pine forests on both sites appear well adapted to management that includes frequent cycles of prescribed surface fire and periodic partial reduction of the forest canopy through selection systems and shelterwood methods.…”

“…Long-term application of single-tree selection results in a forest with a stable uneven-aged structure and an irregular canopy with many gaps of various sizes up to 0.1 ha. In addition to blowdown from severe storms and mortality caused by localized fires and outbreaks of insects and pathogens, lightning and timber harvest are two fairly common disturbances that can augment the size of very small gaps, thus releasing suppressed longleaf pine seedlings (Outcalt, 2008). Uneven-aged systems can be useful approaches for attaining the goals of continuous cover forestry (Mason et al, 1999;Vitkova and Ni Dhubhain, 2013) and retention forestry (Franklin et al, 2007;Gustafsson et al, 2012) by implementing silviculture that emulates natural disturbance regimes, which create and maintain complex structures, natural processes and biological legacies with sufficient recovery intervals to conserve biological diversity, maintain wildlife habitat, support primary productivity and provide ecosystem services (Coates and Burton, 1997;Palik et al, 2002;Mitchell et al, 2006).…”

Snag characteristics and dynamics following natural and artificially induced mortality in a managed loblolly pine forest

“…We observed a fairly stable snag population with offsetting recruitment and loss rates during the pretreatment period. Annual tree mortality rates in the region are known to be low for this age class of pines, with primary causes being lightning strikes, root disease, beetle kill, and, occasionally, prescribed fire (Barnard 1999;Sullivan et al 2003;Outcalt 2008). Moorman et al (1999) documented similarly low annual recruitment rates and a slight net loss over the measurement interval.…”

Analysis of lightning-induced forest fires in Austria

“…The detection efficiency since 1999 on cloud to ground flashes is 98 %. This makes it one of the best-performing LLS worldwide (ALDIS 2009;Anderson 2002;Biagi et al 2007;Castedo-Dorado et al 2011;Diendorfer 2007;Outcalt 2008;Podur et al 2003). The first detection sensor was put into operation in 1991, and archived lightning data are available since 1993.…”