Contingent resistance in longleaf pine (Pinus palustris) growth and defense 10 years following smoldering fires

Abstract

In many fire-prone woodlands and forests, fire exclusion has resulted in substantial litter and duff accumulations capable of long-duration smoldering once fire is reintroduced. While previous research has shown that the soil heating from smoldering fires resulted in short-term reductions in coarse root non-structural carbohydrates and latewood growth, information on the long-term effects of smoldering fire is lacking. Our study compared the effects of three smoldering fire treatments (root only, stem only, root and stem) and two control treatments (no fire and surface fire only) on longleaf pine (Pinus palustris) growth and defense ten years after treatments. We cored 17 to 29 similar sized trees per treatment and measured growth as basal area increment and defense as resin duct properties (e.g., resin duct size, % resin duct area). We

Quantifying carbon and species dynamics under different fire regimes in a southeastern U.S. pineland

“…This is certainly important in low-intensity surface fire regimes (Mitchell et al 2009, Hurteau andBrooks 2011) for estimating carbon and species dynamics through time. These are difficult to estimate because when burn intervals are short (1-to 3-yr return time), post-fire understory and midstory re-growth and regeneration are quick (Starr et al 2015), and overstory survival is high (Glitzenstein et al 1995), though long-term implications exist if fire return intervals increase to within a decade or more (Hartnett and Krofta 1989, Kirkman et al 2004, Slack et al 2016). The longleaf pine (Pinus palustris) ecosystem of the southeastern coastal plain of the United States is an archetype of a forest with a frequent surface fire regime ).…”

Contrasting Impacts of Climate and Competition on Large Sugar Pine Growth and Defense in a Fire-Excluded Forest of the Central Sierra Nevada

“…Climate and competition relationships with growth have been well established [34][35][36], but their influence on defense structures has received markedly less attention [37,38]. Our results suggest that annual carbon allocation to defense structures is not fixed and that both climate and competition influence resin duct characteristics even when incorporating changes in growth.…”

“…All growth and defense models included a log link function in the gamma distribution family to accommodate the non-normal and positively skewed distribution of the response data. Gamma regression has been successfully used in previous tree growth modeling studies in temperate forests [22,57] and longleaf pine resin duct defense models [38]. The previous year's growth (previous BAI) was included as a covariate in the growth models to account for temporal autocorrelation, and current BAI was included in the resin duct models because of its high correlations with growth.…”

“…The relationship between climate and resin duct defense characteristics has been observed in both ponderosa pine and longleaf pine (P. palustris); however, the strength of the relationships and variables of importance were not consistent with our findings. One study in Montana found that ponderosa pine resin duct total area was greater when temperatures were warmer and precipitation was higher during the month of July [30], while another study examining longleaf pine in Florida found that resin duct total area was lower following a dry winter and did not show a significant relationship with temperature [38]. These differences indicate that the relationship between resin duct defense and climate likely varies depending on the species and the climatic regions examined.…”

“…Greater competition has been shown to limit growth for many species [33][34][35], but these relationships can vary depending on tree species [36]. The role of climate and competition on resin duct defenses has generally been less well studied, though some have found more allocation to resin ducts with higher precipitation and temperature [30,[37][38][39].…”