Short-term stem mortality of 10 deciduous broadleaved species following prescribed burning in upland forests of the Southern US

Abstract

In upland forests of the Southern US, management is increasingly focussed on the restoration and maintenance of resilient structures and species compositions, with prescribed burning being the primary tool used to achieve these goals and objectives. In this study, we utilised an extensive dataset comprising 91 burn units and 210 plots across 13 National Park Service lands to examine the relationships between the probability of stem mortality (P(m)) 2 years after prescribed fire and stem size and direct fire effects for 10 common deciduous broadleaved species. Post-fire stem mortality ranged from 6.9% for Quercus alba to 58.9% for Sassafras albidum. The probability of stem mortality was positively associated with maximum bole char height (CHAR) and inversely related to diameter at breast height (DBH) for all 10 deciduous broadleaved species. Model goodness-of-fit varied, with the poorest fit generally associated with firetolerant species and best fit generally associated with fire sensitive species. The information presented contributes to our understanding of post-fire stem mortality and may contribute to the development of fire-related stem mortality models following prescribed burning for eastern tree species. Models should be validated with independent datasets across upland forests types to test for spatial relationships before widespread application.Additional keywords: logistic regression, oak-hickory forests, mixed pine-hardwood forests, post-fire stem mortality. of mesophytic and fire-sensitive species (e.g. Acer rubrum, A. saccharum, Nyssa sylvatica) (Brose et al. 2014). Quantitative data related to the factors associated with species-specific postfire stem mortality in the forests of this region are particularly

Fire and tree death: understanding and improving modeling of fire-induced tree mortality

“…The former predictor is problematic for deciduous species, as crown scorch cannot be assessed during the leafless dormant season. Therefore, some models use bole char in lieu of crown scorch (Brando et al 2012, Keyser et al 2018), but unlike crown scorch, bole char cannot be predicted by standard wildland fire behavior models. In addition, surface fuel consumption at the base of trees is not typically included in models, but may be of particular importance for shallow-rooted species, seedlings, and in longunburned areas (see below).…”

Managing Mixed Stands: Reassessing a Forgotten Stand Type in the Southeastern United States

“…A number of studies examining oak (Quercus spp.) regeneration have shown fire sensitivity decreases with increasing stem size [52][53][54]. Strong sprouting responses to prescribed fire can be expected from species that store large amounts of carbohydrates in their roots such as oak, hickory (Carya spp.…”

“…Sprouting also tends to be promoted more consistently in dormant-season burns [55,58]. Alternatively, prescribed fire has not been shown to be effective at controlling larger advanced regeneration of mesophytic species [54,57,59] In short, while questions regarding the use of prescribed fire in mixed stands remain, research demonstrates that prescribed fire is capable of altering species composition early in stand development, prior to sprouting species gaining sufficient size to escape the effective range of prescribed fire [60].…”

Reversing Mesophication Effects on Understory Woody Vegetation in Mid-Southern Oak Forests

“…To illustrate, stands burned for >60 years had dense midstories if fires occurred every 4 years, but virtually no midstory if fires occurred annually (Knapp et al 2015). Controlling understory densification is often a more immediate concern (Hanberry et al 2014), but maintaining overstories dominated by disturbance-adapted trees will eventually require an understanding of how pauses in fire recurrence influence recruitment (Keyser et al 2017) and subtle differences in how fire affects individual tree species (Keyser et al 2018). Our study lacked a substantial fire-free period, and should be interpreted accordingly.…”

“…Yellow poplar can be similarly described where light is not limiting (Iverson et al 2017). Blackgum and sourwood are shadetolerant and intermediately fire-tolerant, and this pairing makes a xero-or meso-phytic designation difficult (Abrams 2007, Keyser et al 2018). Regardless, both increased in understory density with increasing disturbance.…”