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

Author(s):  
Scott Pokswinski ◽  
Michael R. Gallagher ◽  
Nicholas S. Skowronski ◽  
E. Louise Loudermilk ◽  
Joseph J. O'Brien ◽  
...  

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).

Fire ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 55 ◽  
Author(s):  
Scott Pokswinski ◽  
Michael R. Gallagher ◽  
Nicholas S. Skowronski ◽  
E. Louise Loudermilk ◽  
Joseph J. O’Brien ◽  
...  

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).


2020 ◽  
Vol 50 (7) ◽  
pp. 624-635
Author(s):  
Patrick J. Curtin ◽  
Benjamin O. Knapp ◽  
Steven B. Jack ◽  
Lance A. Vickers ◽  
David R. Larsen ◽  
...  

Recent interest in continuous cover forest management of longleaf pine (Pinus palustris Mill.) ecosystems raises questions of long-term sustainability because of uncertainty in rates of canopy recruitment of longleaf pine trees. We destructively sampled 130 naturally regenerated, midstory longleaf pines across an 11 300 ha, second-growth longleaf pine landscape in southwestern Georgia, United States, to reconstruct individual tree height growth patterns. We tested effects of stand density (using a competition index) and site quality (based on two site classifications: mesic and xeric) on height growth and demographics of midstory trees. We also compared height growth of paired midstory and overstory trees to infer stand regeneration and recruitment dynamics. In low-density stands, midstory trees were younger and grew at greater rates than trees within high-density stands. Midstory trees in low-density stands were mostly from a younger regeneration cohort than their paired overstory trees, whereas midstory–overstory pairs in high-density stands were mostly of the same cohort. Our results highlight the importance of releasing midstory longleaf pine trees from local competition for sustained height growth in partial-harvesting management systems. They also demonstrate patterns of long-term persistence in high-density stands, indicating flexibility in the canopy recruitment process of this shade-intolerant tree species.


2007 ◽  
Vol 31 (4) ◽  
pp. 187-191 ◽  
Author(s):  
John R. Brooks ◽  
Lichun Jiang ◽  
Alexander Clark

Abstract Outside and inside bark diameter measurements were recorded from tree disks obtained at 0-, 0.5-, 2.0-, 4.5-, 6.0-, 16.6-, and at 4-ft-height intervals above 6 ft to a 2-in. diameter outside bark top diameter on 42 longleaf pine trees selected from intensively managed longleaf pine (Pinus palustris Mill.) plantations in Dougherty and Worth Counties in southwest Georgia. Trees were sampled from unthinned, cutover stands in their 11th and 14th growing season, which are currently part of an existing growth and yield study. Sample trees ranged from 2 to 7 in. in diameter and from 18 to 40 ft in total height. Parameters for a segmented polynomial taper and compatible cubic foot volume and weight equation were simultaneously estimated using a seemingly unrelated nonlinear fitting procedure to volumes based on a generalized Newton formula and an overlapping bolt methodology. Average error was approximately 0.25 in., 0.04 ft3, and 2.5 lb for taper, volume, and weight estimation, respectively.


2008 ◽  
Vol 18 (1) ◽  
pp. 13-17 ◽  
Author(s):  
Glenn B. Fain ◽  
Charles H. Gilliam ◽  
Jeff L. Sibley ◽  
Cheryl R. Boyer

The objective of this study was to evaluate the potential for use of container substrates composed of processed whole pine trees (WholeTree). Three species [loblolly pine (Pinus taeda), slash pine (Pinus elliottii), and longleaf pine (Pinus palustris)] of 8- to 10-year-old pine trees were harvested at ground level and the entire tree was chipped with a tree chipper. Chips from each tree species were processed with a hammer mill to pass through a 0.374-inch screen. On 29 June 2005 1-gal containers were filled with substrates, placed into full sun under overhead irrigation, and planted with a single liner (63.4 cm3) of ‘Little Blanche’ annual vinca (Catharanthus roseus). The test was repeated on 27 Aug. 2005 with ‘Raspberry Red Cooler’ annual vinca. Pine bark substrate had about 50% less air space and 32% greater water holding capacity than the other substrates. At 54 days after potting (DAP), shoot dry weights were 15% greater for plants grown in 100% pine bark substrate compared with plants grown in the three WholeTree substrates. However, there were no differences in plant growth indices for any substrate at 54 DAP. Plant tissue macronutrient content was similar among all substrates. Tissue micronutrient content was similar and within sufficiency ranges with the exception of manganese. Manganese was highest for substrates made from slash pine and loblolly pine. Root growth was similar among all treatments. Results from the second study were similar. Based on these results, WholeTree substrates derived from loblolly pine, slash pine, or longleaf pine have potential as an alternative, sustainable source for producing short-term horticultural crops.


2018 ◽  
Vol 11 (1) ◽  
pp. 1 ◽  
Author(s):  
Brooke McCalip ◽  
Brian P. Oswald ◽  
Kathryn R. Kidd ◽  
Yuhui Weng ◽  
Kenneth W. Farrish

Longleaf pine (Pinus palustris) savannas were once dominant across the southeastern U.S., including East Texas and parts of western and central Louisiana. The diverse understory associated with these historical savannas may occasionally be seen today, but not often in longleaf pine ecosystems. This project aimed to define east Texas site characteristics that are necessary to support these ecosystems with a dense and diverse herbaceous understory with little to no midstory cover. Fifty-nine plots across three study sites were established to evaluate the influence of overstory cover, basal area, aspect, elevation, and slope on the number of plant genera present. Forest structure and site characteristics had significant effects on the number of plant genera found. The number of genera increased with higher elevation and slope; as elevation increased, there was a decline in basal area and overstory cover, leading to a more diverse, understory layer. In order to re-establish and maintain a diverse, herbaceous understory in longleaf pine savannas, sites with more open canopies and on slopes with the most solar exposure should be given priority, particularly when planting desired understory species.


1998 ◽  
Vol 22 (3) ◽  
pp. 175-183 ◽  
Author(s):  
Kirsten C. New ◽  
James L. Hanula

Abstract The effects of dormant and growing season prescribed burns on the potential arthropod prey of the red-cockaded woodpecker (Picoides borealis) were studied in longleaf pine (Pinus palustris Mill.) stands on the upper Coastal Plain of South Carolina. Sampling was conducted 0, 1, 2, or 3 yr post-burn. Stands were burned once during the winters of 1991, 1992, 1993, and 1994 or in the summer of 1992. Four types of traps sampled arthropods in the litter layer, the herbaceous understory, and on the bole of pine trees. Woodpecker prey abundance and biomass were sampled continuously from June 30, 1993 to June 30, 1994. Overall arthropod diversity was sampled seasonally in June, October, January, and April of the same year. The different trap types had similar arthropod diversity and evenness, but most had low faunal overlap which indicates that they effectively sampled different parts of the arthropod community. When captures from all trap and prey types were combined for each plot no significant differences were found among winter burned plots or between winter and summer burned plots. However, certain prey types were affected by burning. Among stands burned in winter, spider abundance was highest in samples from the soil/litter layer of stands burned 3 yr prior to sampling. Comparison of stands burned in winter 1992 to those burned in the summer showed that the winter 1992 burns had higher spider and ant (Hymenoptera: Formicidae) biomass on the tree boles. Spiders appeared to be the only group affected by winter burning while spiders and ants were affected by the summer burning. In general, time elapsed after the prescribed burns were applied had little effect on the primary arthropod prey of the red-cockaded woodpecker. South. J. Appl. For. 22(3):175-183.


2007 ◽  
Vol 37 (8) ◽  
pp. 1349-1358 ◽  
Author(s):  
J. Morgan Varner ◽  
J. Kevin Hiers ◽  
Roger D. Ottmar ◽  
Doria R. Gordon ◽  
Francis E. Putz ◽  
...  

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.


2009 ◽  
Vol 39 (7) ◽  
pp. 1357-1365 ◽  
Author(s):  
Thomas L. Eberhardt ◽  
Philip M. Sheridan ◽  
Jolie M. Mahfouz

Monoterpenes in exudates, phloem, and sapwood have received considerable attention relative to the active defenses of pine trees. However, little is known about the composition and function of the heartwood monoterpenes. To address this deficiency, monoterpene contents and relative compositions were determined for sapwood and heartwood samples from longleaf pine ( Pinus palustris Mill.) stumps monitored in the field for a 1 year period postharvest. Gas chromatography – mass spectrometry analysis of sapwood and heartwood sample extracts showed the total monoterpene contents for both declined at essentially the same rate. For sapwood, α-pinene continued to comprise about 75% of all compounds detected, while the proportion of β-pinene declined with time (15%–7%). For the heartwood, lower proportions of both α- and β-pinenes (64% and 10%, respectively) were offset by higher proportions of other monoterpenes (e.g., limonene, α-terpineol, borneol). The low proportion of β-pinene in very old turpentine and lightwood stump samples further suggested the lower stability of this particular monoterpene. While it has not been specifically demonstrated that the monoterpenes have an active role in the decay resistance of longleaf pine stump heartwood, these compounds do persist for a very long time and thus are available should they serve this function.


Dendrobiology ◽  
2020 ◽  
Vol 84 ◽  
pp. 30-38
Author(s):  
Xiongwen Chen ◽  
Dale G. Brockway ◽  
Qinfeng Guok

Longleaf pine is an important tree species in the southeastern United States and studying the temporal patterns of pollen shedding is crucial to a better understanding of its phenology and seed production. In this study, field observation data on the timing of pollen shedding from 1958 to 2013 were analyzed with reference to local weather conditions. Our results indicated that the time of peak pollen shedding after January 1 (TPPS) ranged from 53 days (about February 22) to 95 days (around April 5). There was no significant trend of decreasing TPPS. The number of days with the maximum air temperature above 0 °C was close to the TPPS. The accumulated maximum daily air temperature for the TPPS approximated an average of 1,342 °C. The TPPS declined with an increase in the average air temperature during winters. The time of 80% accumulated pollen density (TAPD) varied from 5 to 32 days, with an average of 13 days. Taylor’s power-law was evident in the TAPD data, with the time group of 10–15 days having an interval time of 2 years. Winter weather was not correlated with the TAPD. These results provide new information concerning the pollen phenology for longleaf pine trees.


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