Overstory tree mortality resulting from reintroducing fire to long-unburned longleaf pine forests: the importance of duff moisture

2007 ◽  
Vol 37 (8) ◽  
pp. 1349-1358 ◽  
Author(s):  
J. Morgan Varner ◽  
J. Kevin Hiers ◽  
Roger D. Ottmar ◽  
Doria R. Gordon ◽  
Francis E. Putz ◽  
...  
Keyword(s):  
Moisture Content ◽  
Tree Mortality ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Pine Forests ◽  
Control Treatment ◽  
Crown Scorch ◽  
Fire Effect ◽  
Minimal Reduction ◽  
Overstory Tree

In forests historically maintained by frequent fire, reintroducing fire after decades of exclusion often causes widespread overstory mortality. To better understand this phenomenon, we subjected 16 fire-excluded (ca. 40 years since fire) 10 ha longleaf pine ( Pinus palustris Mill.) stands to one of four replicated burning treatments based on volumetric duff moisture content (VDMC): wet (115% VDMC); moist (85% VDMC); dry (55% VDMC); and a no-burn control. During the first 2 years postfire, overstory pines in the dry burns suffered the greatest mortality (mean 20.5%); pine mortality in the wet and moist treatments did not differ from the control treatment. Duff reduction was greatest in the dry burns (mean 46.5%), with minimal reduction in the moist and wet burns (14.5% and 5%, respectively). Nested logistic regression using trees from all treatments revealed that the best predictors of individual pine mortality were duff consumption and crown scorch (P < 0.001; R2 = 0.34). Crown scorch was significant only in dry burns, whereas duff consumption was significant across all treatments. Duff consumption was related to moisture content in lower duff (Oa; R2 = 0.78, P < 0.001). Restoring fire to long-unburned forests will require development of burn prescriptions that include the effects of duff consumption, an often overlooked fire effect.

scholarly journals Diurnal Pine Bark Structure Dynamics Affect Properties Relevant to Firebrand Generation

2020 ◽  
Author(s):  
Scott Pokswinski ◽  
Michael R. Gallagher ◽  
Nicholas S. Skowronski ◽  
E. Louise Loudermilk ◽  
Joseph J. O'Brien ◽  
...  
Keyword(s):  
Moisture Content ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Time Of Day ◽  
Diurnal Changes ◽  
Solar Exposure ◽  
Structure Changes ◽  
Pitch Pine ◽  
Pine Trees ◽  
Bark Structure

Firebrands are an important agent of wildfire spread and structure fire ignitions at the wildland urban interface. Bark flake morphology has been highlighted as an important, yet poorly characterized factor in firebrand generation, transport, deposition, and ignition of unburned material. Using pine species where bark flakes are the documented source of embers, we conducted experiments to investigate how bark structure changes in response to diurnal drying. Over a 3-day period in a longleaf pine (Pinus palustris Mill.) stand in Florida, we recorded changes in temperature, moisture content and structure of bark across different facing aspects of mature pine trees to examine the effects of varying solar exposure on bark moisture. We further compared results to bark drying in a pitch pine (Pinus rigida Mill.) plantation in New Jersey. Under all conditions, bark peeled and lifted away from the tree trunk over the study periods. Tree bole aspect and the time of day interacted to significantly affect bark peeling. General temperature increases and moisture content decreases were significantly different between east and west aspects in pitch pine, and with time of day and aspect in longleaf pine. These results illustrate that bark moisture and flakiness is highly dynamic on short time scales, driven largely by solar exposure. These diurnal changes likely influence the probability of firebrand production during fire events via controls on moisture (ignition) and peeling (lofting).

Foliar litter position and decomposition in a fire-maintained longleaf pine – wiregrass ecosystem

2002 ◽  
Vol 32 (6) ◽  
pp. 928-941 ◽  
Author(s):  
Joseph J Hendricks ◽  
Carlos A Wilson ◽  
Lindsay R Boring
Keyword(s):  
Mass Loss ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Soil Surface ◽  
Fire Regimes ◽  
Pine Forests ◽  
N Losses ◽  
Surface Mass ◽  
Decay Constants ◽  
P Immobilization

Foliar litter position and decomposition were assessed in longleaf pine (Pinus palustris Mill.) - wiregrass (Aristida beyrichiana Trin. & Rupr.) woodlands during a 3-year burn interval. Position assessments revealed 57.7 and 67.4% of foliar litter was elevated in wiregrass crowns 1 and 2 years, respectively, following burning. Decomposition assessments revealed soil-surface mass loss decay constants (range 0.097–0.282) similar to those measured in comparable pine forests. However, elevated longleaf pine and wiregrass litter exhibited decay constants (0.052 and 0.074, respectively) 50% lower than corresponding soil-surface rates and among the lowest values in the literature. With the exception of wiregrass, which did not exhibit an immobilization of the nutrients (N, P, Ca, K, and Mg) assessed, foliar litter exhibited either extensive P immobilization with minimal N immobilization or minimal, short-lived immobilization of N, P, or both N and P. The percentage of original N and P remaining after 3 years varied widely among the soil surface (N range 6.3–56.3%; P range 3.4–204.7%) and elevated (N range 76.8–94.9%; P range 52.0–99.2%) litter. These results suggest that fire regimes typically employed in longleaf pine – wiregrass woodlands may balance N losses via volatilization with P limitations via litter immobilization.

Measuring moisture dynamics to predict fire severity in longleaf pine forests

2002 ◽  
Vol 11 (4) ◽  
pp. 267 ◽  
Author(s):  
Sue A. Ferguson ◽  
Julia E. Ruthford ◽  
Steven J. McKay ◽  
David Wright ◽  
Clint Wright ◽  
...  
Keyword(s):  
Forest Floor ◽  
Meteorological Data ◽  
Fire Severity ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Pine Forests ◽  
Fuel Load ◽  
Fuel Moisture ◽  
Weather Stations ◽  
Moisture Conditions

To understand the combustion limit of biomass fuels in a longleaf pine (Pinus palustris) forest, an experiment was conducted to monitor the moisture content of potentially flammable forest floor materials (litter and duff) at Eglin Air Force Base in the Florida Panhandle. While longleaf pine forests are fire dependent ecosystems, a long history of fire exclusion has allowed large amounts of pine litter and duff to accumulate. Reintroducing fire to remove excess fuel without killing the longleaf pine trees requires care to burn under litter and duff moisture conditions that alternately allow fire to carry while preventing root exposure or stem girdle. The study site was divided into four blocks that were burned under litter and duff moisture conditions of wet, moist, dry, and very dry. Throughout the 4-month experiment, portable weather stations continuously collected meteorological data, which included continuous measurements of water content in the forest floor material from in situ, time-domain reflectometers. In addition, volumetric moisture samples were collected almost weekly, and pre-burn fuel load and subsequent consumption were measured for each burn. Meteorological variables from the weather stations compared with trends in fuel moisture showed the influence of relative humidity and precipitation on the drying and wetting rates of the litter and duff. Fuel moisture conditions showed significant influence on patterns of fuel consumption and could lead to an understanding of processes that govern longleaf pine mortality.

Differential impacts of the southern pine beetle, Dendroctonus frontalis, on Pinus palustris and Pinus taeda

2007 ◽  
Vol 37 (8) ◽  
pp. 1427-1437 ◽  
Author(s):  
Nicholas A. Friedenberg ◽  
Brenda M. Whited ◽  
Daniel H. Slone ◽  
Sharon J. Martinson ◽  
Matthew P. Ayres
Keyword(s):  
Pinus Taeda ◽  
Loblolly Pine ◽  
Tree Mortality ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Dendroctonus Frontalis ◽  
Southern Pine Beetle ◽  
Thanasimus Dubius ◽  
Southern Pine ◽  
Pine Beetle

Patterns of host use by herbivore pests can have serious consequences for natural and managed ecosystems but are often poorly understood. Here, we provide the first quantification of large differential impacts of the southern pine beetle, Dendroctonus frontalis Zimmermann, on loblolly pine, Pinus taeda L., and longleaf pine, Pinus palustris P. Mill., and evaluate putative mechanisms for the disparity. Spatially extensive survey data from recent epidemics indicate that, per square kilometre, stands of loblolly versus longleaf pine in four forests (380–1273 km2) sustained 3–18 times more local infestations and 3–116 times more tree mortality. Differences were not attributable to size or age structure of pine stands. Using pheromone-baited traps, we found no differences in the abundance of dispersing D. frontalis or its predator Thanasimus dubius Fabricius between loblolly and longleaf stands. Trapping triggered numerous attacks on trees, but the pine species did not differ in the probability of attack initiation or in the surface area of bark attacked by growing aggregations. We found no evidence for postaggregation mechanisms of discrimination or differential success on the two hosts, suggesting that early colonizers discriminate between host species before a pheromone plume is present.

scholarly journals The impact of Hurricane Michael on longleaf pine habitats in Florida

2019 ◽  
Author(s):  
Nicole E. Zampieri ◽  
Stephanie Pau ◽  
Daniel K. Okamoto
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Tree Mortality ◽  
Size Structure ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Climate Change Impacts ◽  
The North ◽  
Integral Role ◽  
The Impact

AbstractThe longleaf pine (Pinus palustris) ecosystem of the North American Coastal Plain (NACP) is a global biodiversity hotspot. Disturbances such as tropical storms play an integral role in ecosystem maintenance in these systems. However, altered disturbance regimes as a result of climate change may be outside the historical threshold of tolerance. Hurricane Michael impacted the Florida panhandle as a Category 5 storm on October 10th, 2018. In this study, we estimate the extent of Florida longleaf habitat that was directly impacted by Hurricane Michael. We then quantify the impact of Hurricane Michael on tree density and size structure using a Before-After study design at four sites (two wet flatwood and two upland pine communities). Finally, we identify the most common type of tree damage at each site and community type. We found that 39% of the total remaining extent of longleaf pine habitat was affected by the storm in Florida alone. Tree mortality ranged from 1.3% at the site furthest from the storm center to 88.7% at the site closest. Most of this mortality was in mature sized trees (92% mortality), upon which much of the biodiversity in this habitat depends. As the frequency and intensity of extreme events increases, management plans that mitigate for climate change impacts need to account for large-scale stochastic mortality events in order to effectively preserve critical habitats.

scholarly journals Millennial-Scale Carbon Storage in Natural Pine Forests of the North Carolina Lower Coastal Plain: Effects of Artificial Drainage in a Time of Rapid Sea Level Rise

Land ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1294
Author(s):  
Maricar Aguilos ◽  
Charlton Brown ◽  
Kevan Minick ◽  
Milan Fischer ◽  
Omoyemeh J. Ile ◽  
...  
Keyword(s):  
North Carolina ◽  
Sea Level ◽  
Coastal Plain ◽  
Aboveground Biomass ◽  
Tree Mortality ◽  
Coastal Wetland ◽  
Accumulation Rate ◽  
Pine Forests ◽  
Lower Coastal Plain ◽  
Overstory Tree

Coastal forested wetlands provide important ecosystem services along the southeastern region of the United States, but are threatened by anthropogenic and natural disturbances. Here, we examined the species composition, mortality, aboveground biomass, and carbon content of vegetation and soils in natural pine forests of the lower coastal plain in eastern North Carolina, USA. We compared a forest clearly in decline (termed “ghost forest”) adjacent to a roadside canal that had been installed as drainage for a road next to an adjacent forest subject to “natural” hydrology, unaltered by human modification (termed “healthy forest”). We also assessed how soil organic carbon (SOC) accumulation changed over time using 14C radiocarbon dating of wood sampled at different depths within the peat profile. Our results showed that the ghost forest had a higher tree density at 687 trees ha−1, and was dominated by swamp bays (Persea palustric), compared to the healthy forest, which had 265 trees ha−1 dominated by pond pine (Pinus serotina Michx). Overstory tree mortality of the ghost forest was nearly ten times greater than the healthy forest (p < 0.05), which actually contributed to higher total aboveground biomass (55.9 ± 12.6 Mg C ha−1 vs. 27.9 ± 8.7 Mg ha−1 in healthy forest), as the dead standing tree biomass (snags) added to that of an encroaching woody shrub layer during ecosystem transition. Therefore, the total aboveground C content of the ghost forest, 33.98 ± 14.8 Mg C ha−1, was higher than the healthy forest, 24.7 ± 5.2 Mg C ha−1 (p < 0.05). The total SOC stock down to a 2.3 m depth in the ghost forest was 824.1 ± 46.2 Mg C ha−1, while that of the healthy forest was 749.0 ± 170.5 Mg C ha−1 (p > 0.05). Carbon dating of organic sediments indicated that, as the sample age approaches modern times (surface layer year 2015), the organic soil accumulation rate (1.11 to 1.13 mm year−1) is unable to keep pace with the estimated rate of recent sea level rise (2.1 to 2.4 mm year−1), suggesting a causative relationship with the ecosystem transition occurring at the site. Increasing hydrologic stress over recent decades appears to have been a major driver of ecosystem transition, that is, ghost forest formation and woody shrub encroachment, as indicated by the far higher overstory tree mortality adjacent to the drainage ditch, which allows the inland propagation of hydrologic/salinity forcing due to SLR and extreme storms. Our study documents C accumulation in a coastal wetland over the past two millennia, which is now threatened due to the recent increase in the rate of SLR exceeding the natural peat accumulation rate, causing an ecosystem transition with unknown consequences for the stored C; however, much of it will eventually be returned to the atmosphere. More studies are needed to determine the causes and consequences of coastal ecosystem transition to inform the modeling of future coastal wetland responses to environmental change and the estimation of regional terrestrial C stocks and flux.

scholarly journals Diurnal Pine Bark Structure Dynamics Affect Properties Relevant to Firebrand Generation

Fire ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 55 ◽  
Author(s):  
Scott Pokswinski ◽  
Michael R. Gallagher ◽  
Nicholas S. Skowronski ◽  
E. Louise Loudermilk ◽  
Joseph J. O’Brien ◽  
...  
Keyword(s):  
Moisture Content ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Time Of Day ◽  
Diurnal Changes ◽  
Solar Exposure ◽  
Structure Changes ◽  
Pitch Pine ◽  
Pine Trees ◽  
Bark Structure

Firebrands are an important agent of wildfire spread and structure fire ignitions at the wildland urban interface. Bark flake morphology has been highlighted as an important yet poorly characterized factor in firebrand generation, transport, deposition, and ignition of unburned material. Using pine species where bark flakes are the documented source of embers, we conducted experiments to investigate how bark structure changes in response to diurnal drying. Over a three-day period in a longleaf pine (Pinus palustris Mill.) stand in Florida, we recorded changes in temperature, moisture content, and structure of bark across different facing aspects of mature pine trees to examine the effects of varying solar exposure on bark moisture. We further compared results to bark drying in a pitch pine (Pinus rigida Mill.) plantation in New Jersey. Under all conditions, bark peeled and lifted away from the tree trunk over the study periods. Tree bole aspect and the time of day interacted to significantly affect bark peeling. General temperature increases and moisture content decreases were significantly different between east and west aspects in pitch pine, and with time of day and aspect in longleaf pine. These results illustrate that bark moisture and flakiness is highly dynamic on short time scales, driven largely by solar exposure. These diurnal changes likely influence the probability of firebrand production during fire events via controls on moisture (ignition) and peeling (lofting).

scholarly journals Physiological Mechanisms of Foliage Recovery after Spring or Fall Crown Scorch in Young Longleaf Pine (Pinus palustris Mill.)

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 208
Author(s):  
Mary Anne S. Sayer ◽  
Michael C. Tyree ◽  
Eric A. Kuehler ◽  
John K. Jackson ◽  
Dylan N. Dillaway
Keyword(s):  
Gas Exchange ◽  
Prescribed Fire ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Growing Season ◽  
Stem Growth ◽  
Starch Accumulation ◽  
Crown Scorch ◽  
Growth Loss ◽  
Developmental Responses

We hypothesized that physiological and morphological responses to prescribed fire support the post-scorch foliage recovery and growth of young longleaf pine. Two studies conducted in central Louisiana identified three means of foliage regrowth after fire that included an increase in the gas exchange rate of surviving foliage for 3 to 4 months after fire. Saplings also exhibited crown developmental responses to repeated fire that reduced the risk of future crown scorch. Starch reserves were a source of carbon for post-scorch foliage regrowth when fire was applied in the early growing season. However, the annual dynamics of starch accumulation and mobilization restricted its effectiveness for foliage regrowth when fire was applied late in the growing season. As such, post-scorch foliage regrowth became increasingly dependent on photosynthesis as the growing season progressed. Additionally, the loss of foliage by fire late in the growing season interrupted annual starch dynamics and created a starch void between the time of late growing season fire and mid-summer of the next year. The occurrence of drought during both studies revealed barriers to foliage reestablishment and normal stem growth among large saplings. In study 1, spring water deficit at the time of May fire was associated with high crown scorch and poor foliage and stem growth among large saplings. We attribute this lag in stem growth to three factors: little surviving foliage mass, low fascicle gas exchange rates, and poor post-scorch foliage recovery. In study 2, May fire during a short window of favorable burning conditions in the tenth month of a 20-month drought also reduced stem growth among large saplings but this growth loss was not due to poor post-scorch foliage recovery. Application of this information to prescribed fire guidelines will benefit young longleaf pine responses to fire and advance efforts to restore longleaf pine ecosystems.

Pine cones facilitate ignition of forest floor duff

2013 ◽  
Vol 43 (5) ◽  
pp. 512-516 ◽  
Author(s):  
Jesse K. Kreye ◽  
J. Morgan Varner ◽  
Christopher J. Dugaw ◽  
Jing Cao ◽  
Jonathan Szecsei ◽  
...  
Keyword(s):  
Forest Floor ◽  
Mineral Content ◽  
Tree Mortality ◽  
Pinus Palustris ◽  
Relative Effect ◽  
Coniferous Forests ◽  
Fuel Moisture ◽  
Ignition And Combustion ◽  
Pine Cones ◽  
Overstory Tree

The ignition and combustion of forest floor duff are poorly understood yet have been linked to soil heating and overstory tree mortality in many temperate coniferous forests. Research to date has focused on the characteristics of duff that facilitate ignition and spread, including fuel moisture, mineral content, and depth. Field observations suggest that the presence of pine cones on and within the forest floor might facilitate ignition of intermixed forest floor fuels. We investigated the effect of cone fuel additions on the ignition of underlying forest floor from fuels collected in long-unburned longleaf pine (Pinus palustris Mill.) forests in northern Florida, USA. Fuels were wetted to threshold gravimetric moisture contents to evaluate the relative effect on ignition. In stark contrast to fuel beds without cones, in which duff ignition only occurred in 17% of samples, those with cones added ignited the underlying duff 94% of the time. Flame heights were 40% taller and flaming duration was 47% longer in fuel beds with cones. Where present, pine cones act as vectors of ignition for forest floor fuels, and their role in fires deserves more attention to enhance our understanding of forest floor combustion.

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