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.

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.

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.

Spatial and temporal variability of forest floor duff characteristics in long-unburnedPinus palustrisforests

2014 ◽  
Vol 44 (12) ◽  
pp. 1477-1486 ◽  
Author(s):  
Jesse K. Kreye ◽  
J. Morgan Varner ◽  
Christopher J. Dugaw
Keyword(s):  
Spatial Autocorrelation ◽  
Bulk Density ◽  
Temporal Variability ◽  
Forest Floor ◽  
Humus Horizon ◽  
Fire Management ◽  
Pinus Palustris ◽  
Coniferous Forests ◽  
Spatial And Temporal Variability ◽  
In Fire

Duff fires (smouldering in fermentation and humus forest floor horizons) and their consequences have been documented in fire-excluded ecosystems but with little attention to their underlying drivers. Duff characteristics influence the ignition and spread of smouldering fires, and their spatial patterns on the forest floor may be an important link to the heterogeneity of consumption observed following fires. We evaluated fuel bed characteristics (depths, bulk densities, and moisture) of duff in a long-unburned longleaf pine (Pinus palustris Mill.) forest and corresponding spatial variation across 100to 103m scales. Fermentation and humus horizon depths both varied (∼100% coefficient of variation) but with moderate to strong spatial autocorrelation at fine scales. Fermentation bulk density varied less than humus bulk density, which varied considerably at fine scales. Fermentation horizons held more moisture (average 49%–172%) and were much more variable than humus following rainfall, which remained stable and relatively dry (average 28%–62%). Humus moisture was moderately autocorrelated at fine scales, but fermentation moisture was highly variable, showing no evidence of spatial autocorrelation under dry, intermediate, or wet conditions. Observations from this study highlight the underlying spatial variability in duff, informing future sampling and fire management efforts in these long-unburned coniferous forests.

scholarly journals Intra-Annual Variation in Soil C, N and Nutrients Pools after Prescribed Fire in a Mississippi Longleaf Pine (Pinus palustris Mill.) Plantation

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 181
Author(s):  
John R. Butnor ◽  
Kurt H. Johnsen ◽  
Christopher A. Maier ◽  
C. Dana Nelson
Keyword(s):  
Prescribed Fire ◽  
Forest Floor ◽  
Soil Chemistry ◽  
Annual Variation ◽  
Longleaf Pine ◽  
Pinus Palustris ◽  
Southern Pine ◽  
Soil C ◽  
Soil C And N ◽  
C And N

Prescribed fire is an essential tool that is widely used for longleaf pine (Pinus palustris Mill.) stand management; periodic burning serves to reduce competition from woody shrubs and fire-intolerant trees and enhance herbaceous diversity. Low-intensity, prescribed burning is thought to have minimal long-term impact on soil chemistry in southern pine forests, although few studies report the intra-annual variation in soil chemistry after burning. We monitored changes in C, N, oxidation resistant C (CR), pH and elemental nutrients in the forest floor and soil (0–5, 5–10 cm depths) before and after burning (1, 3, 6, 12 months) in a mature longleaf pine plantation at the Harrison Experimental Forest, near Saucier, Mississippi. Prescribed fire consumed much of the forest floor (11.3 Mg ha−1; −69%), increased soil pH and caused a pulse of C, N and elemental nutrients to flow to the near surface soils. In the initial one to three months post-burn coinciding with the start of the growing season, retention of nutrients by soil peaked. Most of the N (93%), Ca (88%), K (96%) and Mg (101%), roughly half of the P (48%) and Mn (52%) and 25% of the C lost from the forest floor were detected in the soil and apparently not lost to volatilization. By month 12, soil C and N pools were not different at depths of 0–5 cm but declined significantly below pre-burn levels at depths of 5–10 cm, C −36% (p < 0.0001), N −26% (p = 0.003), contrary to other examples in southern pine ecosystems. In the upper 5 cm of soil, only Cu (−49%) remained significantly lower than pre-burn contents by month 12, at depths of 5–10 cm, Cu (−76%), Fe (−22%), K (−51%), Mg (−57%), Mn (−82%) and P (−52%) remain lower at month 12 than pre-burn contents. Burning did not increase soil CR content, conversely significant declines in CR occurred. It appears that recovery of soil C and N pools post-burn will require more time on this site than other southern pine forests.

Evaluating the applicability of predicting dead fine fuel moisture based on the hourly Fine Fuel Moisture Code in the south-eastern Xing’an Mountains of China

2017 ◽  
Vol 26 (2) ◽  
pp. 167 ◽  
Author(s):  
Jili Zhang ◽  
Xiaoyang Cui ◽  
Rui Wei ◽  
Yan Huang ◽  
Xueying Di
Keyword(s):  
Scots Pine ◽  
Forest Floor ◽  
Loss Rate ◽  
Weather Data ◽  
Fuel Moisture ◽  
The South ◽  
Fire Control ◽  
South Eastern ◽  
Great Xing’An Mountains ◽  
Observation Period

To evaluate the applicability of the hourly Fine Fuel Moisture Code (FFMC) to the south-eastern Great Xing’an Mountains, dead fine fuel moisture (Mf) was observed under less-sheltered and sheltered conditions in Scots pine (Pinus sylvestris var. mongolica), larch (Larix gmelinii) and oak (Quercus mongolicus) stands during the summer and autumn of 2014. Standard FFMC and locally calibrated FFMC values calculated hourly were tested using Mf observations and weather data, and the results showed that the Mf loss rate in the less-sheltered forest floor was markedly higher than that in the sheltered forest floor (P < 0.05). The standard hourly FFMC underestimated Mf, especially in stands of larch, the dominant species in the Great Xing’an Mountains, and Mf for rainy days in Scots pine and oak stands. However, the calibrated hourly FFMC predicted Mf in all three forest stands very well (R2 ranged from 0.920 to 0.969; mean absolute errorfrom 2.93 to 6.93, and root-mean-squared errorfrom 4.09 to 7.87), which suggested that it was sufficiently robust for those stands around the observation period. This study will improve the accuracy of Mf predictions to aid fire control efforts in the Great Xing’an Mountains and provide a basis for hourly FFMC model calibration.

Nutrient cycling in Huntington Forest and Turkey Lakes deciduous stands: nitrogen and sulfur

1992 ◽  
Vol 22 (4) ◽  
pp. 457-464 ◽  
Author(s):  
M.J. Mitchell ◽  
N.W. Foster ◽  
J.P. Shepard ◽  
I.K. Morrison
Keyword(s):  
New York ◽  
Forest Floor ◽  
Sugar Maple ◽  
Tree Mortality ◽  
C:N Ratio ◽  
Mineral Soil ◽  
Stand Age ◽  
Adirondack Mountains ◽  
Contributing Factors ◽  
Turkey Lakes Watershed

Biogeochemical cycling of S and N was quantified at two hardwood sites (Turkey Lakes watershed (TLW) and Huntington Forest (HF)) that have sugar maple (Acersaccharum Marsh.) as the major overstory component and are underlain by Spodosols (Podzols). TLW and HF are located in central Ontario (Canada) and the Adirondack Mountains of New York (U.S.A), respectively. Major differences between the TLW and HF sites included stand age (300 and 100 years for TLW and HF, respectively), age of dominant trees (150–300 and 100 years for TLW and HF, respectively), and the presence of American beech (Fagusgrandifolia Ehrh.) at HF as well as lower inputs of SO42− and NO3− (differences of 99 and 31 mol ion charge (molc)•ha−1•year−1, respectively) at TLW. There was an increase in concentration of SO42− and NO3− after passage through the canopy at both sites. A major difference in the anion chemistry of the soil solution between the sites was the much greater leaching of NO3− at TLW compared with HF (1300 versus 18 molc•ha−1•year−1, respectively). At HF, but not TLW, there was a marked increase in SO42− flux (217 molc•ha−1•year−1) when water leached from the forest floor through the mineral soil. The mineral soil was the largest pool (>80%) of N and S for both sites. The mineral soil of TLW had a C:N ratio of 16:1, which is much narrower than the 34:1 ratio at HF. This former ratio should favor accumulation of NH44+ and NO3− and subsequent NO3− leaching. Laboratory measurements suggest that the forest floor of TLW may have higher N mineralization rates than HF. Fluxes of N and S within the vegetation were generally similar at both sites, except that net requirement of N at TLW was substantially lower (difference of 9.4 kg N•ha−1•year−1). The higher NO3− leaching from TLW compared with HF may be attributed mostly to stand maturity coupled with tree mortality, but the absence of slow decomposing beech leaf litter and lower C:N ratio in the soil of the former site may also be contributing factors.

Prediction of forest-floor moisture content under diverse jack pine canopy conditions

1989 ◽  
Vol 19 (11) ◽  
pp. 1483-1487 ◽  
Author(s):  
Z. Chrosciewicz
Keyword(s):  
Forest Floor ◽  
Mineral Soil ◽  
Jack Pine ◽  
Fuel Moisture ◽  
Weather Index ◽  
Fire Weather Index ◽  
Moisture Contents ◽  
Straight Line ◽  
Best Fitting ◽  
Pure Surface

Moisture contents of organic forest-floor materials were studied by strata in a semimature jack pine (Pinusbanksiana Lamb.) stand in relation to their within-stand locations and changes in both duff moisture code and fine fuel moisture code, the two weather-based components of the Canadian Forest Fire Weather Index System. The resulting best-fitting curvilinear regressions (Y = aebX) of the duff moisture code showed distinctive patterns of variation so that both the surface and subsurface forest-floor strata were consistently more moist in stand openings than under stand canopy. An initial moisture inversion between the surface and subsurface forest-floor materials manifested itself near the start of the regressions wherever live Schreber's moss (Pleuroziumschreberi (Brit.) Mitt.) and litter were the combined surface materials; otherwise, pure surface litter was consistently drier than the subsurface materials. Combinations of all these materials down to mineral soil showed intermediate moisture contents both in stand openings and under stand canopy. In contrast, the best-fitting regressions of the fine fuel moisture code just for surface forest-floor strata were of the straight line (Y = a + bX) category and had generally lower r2 values than those for the corresponding curvilinear regressions (Y = aebX) of the duff moisture code.

The contribution of competition to tree mortality in old-growth coniferous forests

2011 ◽  
Vol 261 (7) ◽  
pp. 1203-1213 ◽  
Author(s):  
Adrian Das ◽  
John Battles ◽  
Nathan L. Stephenson ◽  
Phillip J. van Mantgem
Keyword(s):  
Tree Mortality ◽  
Coniferous Forests ◽  
Old Growth
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