scholarly journals Fire Scars Negatively Affect Hydraulic Conductivity in White Oak (Quercus alba)

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 812
Author(s):  
Justin R. Dee ◽  
Michael C. Stambaugh ◽  
Kevin T. Smith ◽  
Daniel C. Dey
Keyword(s):  
Hydraulic Conductivity ◽  
Cross Sections ◽  
Stand Structure ◽  
Analysis Tool ◽  
White Oak ◽  
Fire Scars ◽  
Fire Scar ◽  
Vessel Area ◽  
Forest Stand Structure ◽  
The Mean

Fire management is increasingly used to manage forest stand structure and dynamics. Relatively intense fires can injure the tree stem and induce fire scar formation, affecting subsequent tree growth and wood quality. Here, we consider the physiological effects of fire scarring in white oak. Potential hydraulic conductivity, estimated from the mean vessel area and vessel number, was determined for growth rings formed before, during, and after the year of injury. We measured vessel anatomy using the ROXAS image analysis tool on the cross-sections of 14 white oaks of various ages with fire scars originating in different years through the late 19th and early 20th century. We found that the mean vessel area and potential hydraulic conductivity were significantly reduced for the year of and the year immediately following fire injury. After this two-year period, mean vessel area returned to levels present in wood formed prior to the injury. Age when scarred, radius from the pith when scarred, scar height above ground, and percentage of circumference scarred did not explain the degree to which potential hydraulic conductivity was lost in the fire scar year compared to the year prior. Overall, the magnitude of reduction in potential hydraulic conductivity was small but significant. An earlier study on the same cross-sections verified no reductions in radial growth after fire injury. Thus, it is likely that the conductance of older rings is adequate to sustain conductance. Nonetheless, we recommend further investigation, in particular, the ability to predict how tree size, age, position along a slope, and other variables may influence the degree of wounding and possible losses of potential hydraulic conductivity after the fire. Information like this for white oak and other common tree species may help elucidate the physiological impacts fire injuries have on trees existing in forest stands with periodic fire.

A cross-dated fire history from coast redwood near Redwood National Park, California

1994 ◽  
Vol 24 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Peter M. Brown ◽  
Thomas W. Swetnam
Keyword(s):  
Cross Sections ◽  
National Park ◽  
Fire History ◽  
Fire Frequency ◽  
Fire Scars ◽  
Coast Redwood ◽  
Complete Representation ◽  
Fire Scar ◽  
Redwood National Park ◽  
The Mean

Cross sections from coast redwood trees (Sequoiasempervirens (D.Don.)Endl.) in and near Redwood National Park were dendrochronologically cross-dated and used to develop a fire history from 1714 to 1985. A master chronology for the study area was first developed from old-growth trees and provided dating control for fire-scarred samples. Redwood offers a challenge for dendrochronology owing to partially absent rings (ring wedging) and uniform ring widths (complacency). Cross dating was successful in portions of 12 of 24 fire-scarred trees. Fire events were dated by noting the position of fire scars and other fire-associated ring structures (resin ducts, double latewood, growth releases, and ring separations) in the cross-dated ring series. Using only dates of fire scars, the mean fire interval (MFI) was 9.9 years from the first recorded fire in 1714 to the last in 1962. The MFI was 8.0 years for the best represented (greatest sample depth) presettlement period from 1714 to 1881. Using dates for all fire-associated ring features, the MFI from 1714 to 1962 was 7.0 years and from 1714 to 1881 was 6.0 years. Use of all fire-associated ring characteristics is argued to be a more complete representation of past fire frequency due to possible under-representation of fire-scar records from stump-top samples. Based upon scar positions within annual rings, fires occurred predominately late in the growing season or after growth ceased for the year. The mean fire intervals determined are shorter than those reported in all except one other fire history study from coast redwood and suggest that fire frequency in redwood may have been underestimated in many past studies.

Anatomical changes induced by fire-damaged cambium in two native tree species of the Chaco Region, Argentina

IAWA Journal ◽  
2010 ◽  
Vol 31 (3) ◽  
pp. 283-292 ◽  
Author(s):  
Sandra Bravo
Keyword(s):  
Cross Sections ◽  
Wood Quality ◽  
Cambial Activity ◽  
Wood Formation ◽  
Vessel Diameter ◽  
Fire Damage ◽  
Fire Scars ◽  
Fire Scar ◽  
Chaco Region ◽  
Altered Zone

This study examined anatomical responses to fire damage of the cambium in Schinopsis lorentzii and Aspidosperma quebracho-blanco. Bole cross sections were extracted from specimens with external signs of fire damage. Samples were taken from zones designated normal, discoloured and wound altered. The vessel, fibre, axial and ray parenchyma percentages, tangential vessel diameter, vessels per mm2, rays per mm, and ray width and height of these zones were compared. Fire scars and fire marks were identified on cross sections of S. lorentzii and A. quebracho-blanco. The fire marks reflect minor wounds that did not affect wood formation. The fire scars, on the other hand, are the result of wounds that interrupted cambial activity thus affecting the shape of the bole and causing discolouration of pre-existing wood adjacent to wounds. The wood formed after fire damage included callus, barrier zones at fire scar edges and the formation of ribs of wound wood. The wound altered zone was characterised by a decrease in the percentage of vessels and fibres, an increase in the percentage of axial parenchyma, the formation of grouped rays, a decrease in vessel tangential diameter, and occurrence of fibres with atypical structure. Disorientation in the axial xylem system was observed in the barrier zone. The anatomical responses to cambium damage and formation of discoloured wood and woundwood ribs suggest that wood quality and utilisable volume of bole in the studied species is affected by fire.

An experimental evaluation of fire history reconstruction using dendrochronology in white oak (Quercus alba)

2007 ◽  
Vol 37 (4) ◽  
pp. 806-816 ◽  
Author(s):  
Ryan W. McEwan ◽  
Todd F. Hutchinson ◽  
Robert D. Ford ◽  
Brian C. McCarthy
Keyword(s):  
Tree Ring ◽  
Cross Sections ◽  
Fire History ◽  
Management Practices ◽  
Fire Regimes ◽  
Prescribed Fires ◽  
White Oak ◽  
Fire Scars ◽  
Treatment Unit ◽  
Dendrochronological Analysis

Dendrochronological analysis of fire scars on tree cross sections has been critically important for understanding historical fire regimes and has influenced forest management practices. Despite its value as a tool for understanding historical ecosystems, tree-ring-based fire history reconstruction has rarely been experimentally evaluated. To examine the efficacy of dendrochronological analysis for detecting fire occurrence in oak forests, we analyzed tree cross sections from sites in which prescribed fires had been recently conducted. The first fire in each treatment unit created a scar in at least one sample, but the overall percentage of samples containing scars in fire years was low (12%). We found that scars were created by 10 of the 15 prescribed fires, and the five undetected fires all occurred in sites where fire had occurred the previous year. Notably, several samples contained scars from known fire-free periods. In summary, our data suggest that tree-ring analysis is a generally effective tool for reconstructing historical fire regimes, although the following points of uncertainty were highlighted: (i) consecutive annual burns may not create fire scars and (ii) wounds that are morphologically indistinguishable from fire scars may originate from nonfire sources.

scholarly journals Assessing Wood and Soil Carbon Losses from a Forest-Peat Fire in the Boreo-Nemoral Zone

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 880
Author(s):  
Andrey Sirin ◽  
Alexander Maslov ◽  
Dmitry Makarov ◽  
Yakov Gulbe ◽  
Hans Joosten
Keyword(s):  
Soil Carbon ◽  
Stand Structure ◽  
Peat Soil ◽  
Burned Area ◽  
Tree Biomass ◽  
Carbon Loss ◽  
Forest Stand Structure ◽  
Peat Fire ◽  
Peat Fires ◽  
Carbon Losses

Forest-peat fires are notable for their difficulty in estimating carbon losses. Combined carbon losses from tree biomass and peat soil were estimated at an 8 ha forest-peat fire in the Moscow region after catastrophic fires in 2010. The loss of tree biomass carbon was assessed by reconstructing forest stand structure using the classification of pre-fire high-resolution satellite imagery and after-fire ground survey of the same forest classes in adjacent areas. Soil carbon loss was assessed by using the root collars of stumps to reconstruct the pre-fire soil surface and interpolating the peat characteristics of adjacent non-burned areas. The mean (median) depth of peat losses across the burned area was 15 ± 8 (14) cm, varying from 13 ± 5 (11) to 20 ± 9 (19). Loss of soil carbon was 9.22 ± 3.75–11.0 ± 4.96 (mean) and 8.0–11.0 kg m−2 (median); values exceeding 100 tC ha−1 have also been found in other studies. The estimated soil carbon loss for the entire burned area, 98 (mean) and 92 (median) tC ha−1, significantly exceeds the carbon loss from live (tree) biomass, which averaged 58.8 tC ha−1. The loss of carbon in the forest-peat fire thus equals the release of nearly 400 (soil) and, including the biomass, almost 650 tCO2 ha−1 into the atmosphere, which illustrates the underestimated impact of boreal forest-peat fires on atmospheric gas concentrations and climate.

scholarly journals Forest stand structure and coarse woody debris determine the biodiversity of beetle communities in Mediterranean mountain beech forests

2021 ◽  
pp. e01637
Author(s):  
Francesco Parisi ◽  
Michele Innangi ◽  
Roberto Tognetti ◽  
Fabio Lombardi ◽  
Gherardo Chirici ◽  
...  
Keyword(s):  
Coarse Woody Debris ◽  
Stand Structure ◽  
Woody Debris ◽  
Forest Stand ◽  
Beech Forests ◽  
Forest Stand Structure

scholarly journals Aerodynamics of smooth and rough square-section prisms at incidence in very high Reynolds-number cross-flows

2021 ◽  
Vol 62 (3) ◽  
Author(s):  
Nils Paul van Hinsberg
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Surface Boundary ◽  
Experimental Proof ◽  
Surface Boundary Layer ◽  
Pitch Moment ◽  
The Mean ◽  
High Reynolds

Abstract The aerodynamics of smooth and slightly rough prisms with square cross-sections and sharp edges is investigated through wind tunnel experiments. Mean and fluctuating forces, the mean pitch moment, Strouhal numbers, the mean surface pressures and the mean wake profiles in the mid-span cross-section of the prism are recorded simultaneously for Reynolds numbers between 1$$\times$$ × 10$$^{5}$$ 5 $$\le$$ ≤ Re$$_{D}$$ D $$\le$$ ≤ 1$$\times$$ × 10$$^{7}$$ 7 . For the smooth prism with $$k_s$$ k s /D = 4$$\times$$ × 10$$^{-5}$$ - 5 , tests were performed at three angles of incidence, i.e. $$\alpha$$ α = 0$$^{\circ }$$ ∘ , −22.5$$^{\circ }$$ ∘ and −45$$^{\circ }$$ ∘ , whereas only both “symmetric” angles were studied for its slightly rough counterpart with $$k_s$$ k s /D = 1$$\times$$ × 10$$^{-3}$$ - 3 . First-time experimental proof is given that, within the accuracy of the data, no significant variation with Reynolds number occurs for all mean and fluctuating aerodynamic coefficients of smooth square prisms up to Reynolds numbers as high as $$\mathcal {O}$$ O (10$$^{7}$$ 7 ). This Reynolds-number independent behaviour applies to the Strouhal number and the wake profile as well. In contrast to what is known from square prisms with rounded edges and circular cylinders, an increase in surface roughness height by a factor 25 on the current sharp-edged square prism does not lead to any notable effects on the surface boundary layer and thus on the prism’s aerodynamics. For both prisms, distinct changes in the aerostatics between the various angles of incidence are seen to take place though. Graphic abstract

scholarly journals Extension of Pin-Based Point-Wise Energy Slowing-Down Method for VHTR Fuel with Double Heterogeneity

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2179
Author(s):  
Tae-Young Han ◽  
Jin-Young Cho ◽  
Chang-Keun Jo ◽  
Hyun-Chul Lee
Keyword(s):  
Cross Sections ◽  
Cell Model ◽  
Unit Cell ◽  
Moderation Effect ◽  
Slowing Down ◽  
Matrix Layer ◽  
The Mean ◽  
Dancoff Factor ◽  
Double Heterogeneity ◽  
Very High

For the resonance treatment of a very high temperature reactors (VHTR) fuel with the double heterogeneity, an extension of the pin-based pointwise energy slowing-down method (PSM) was developed and implemented into DeCART. The proposed method, PSM-double heterogeneity (DH), has an improved spherical unit cell model with an explicit tri-structural isotropic (TRISO) model, a matrix layer, and a moderator for reflecting the moderation effect. The moderator volume was analytically derived using the relation of the Dancoff factor and the mean chord length. In the first step, the pointwise homogenized cross-sections for the compact was obtained after solving the slowing down equation for the spherical unit cell. Then, the shielded cross-section for the homogenized fuel compact was generated using the original PSM. The verification calculations were performed for the fuel pins with various packing fractions, compact sizes, TRISO sizes, and fuel temperatures. Additionally, two fuel block problems with very different sizes were examined and the depletion calculation was carried out for investigating the accuracy of the proposed method. They revealed that the PSM-DH has a good performance in the VHTR problems.

Stand-Level Forest Structure and Avian Habitat: Scale Dependencies in Predicting Occurrence in a Heterogeneous Forest

2008 ◽  
Vol 54 (1) ◽  
pp. 36-46
Author(s):  
Katherine Manaras Smith ◽  
William S. Keeton ◽  
Therese M. Donovan ◽  
Brian Mitchell
Keyword(s):  
Forest Structure ◽  
Stand Structure ◽  
Site Occupancy ◽  
Territory Size ◽  
Weight Of Evidence ◽  
Habitat Models ◽  
Point Counts ◽  
Forest Stand Structure ◽  
Habitat Scale

Abstract We explored the role of stand-level forest structure and spatial extent of forest sampling in models of avian occurrence in northern hardwood-conifer forests for two species: black-throated blue warbler (Dendroica caerulescens) and ovenbird (Seiurus aurocapillus). We estimated site occupancy from point counts at 20 sites and characterized the forest structure at these sites at three spatial extents (0.2, 3.0, and 12.0 ha). Weight of evidence was greatest for habitat models using forest stand structure at the 12.0-ha extent and diminished only slightly at the 3.0-ha extent, a scale that was slightly larger than the average territory size of both species. Habitat models characterized at the 0.2-ha extent had low support, yet are the closest in design to those used in many of the habitat studies we reviewed. These results suggest that the role of stand-level vegetation may have been underestimated in the past, which will be of interest to land managers who use habitat models to assess the suitability of habitat for species of concern.

Evaluation of Single-Hole Hydraulic Tests in Fractured Crystalline Rock by Steady-State and Transient Methods: A Comparison

1985 ◽  
Vol 50 ◽  
Author(s):  
J-E. Andersson ◽  
O. Persson
Keyword(s):  
Steady State ◽  
Hydraulic Conductivity ◽  
Flow Pattern ◽  
Transient Analysis ◽  
Crystalline Rock ◽  
Steady State Analysis ◽  
Single Hole ◽  
The Mean ◽  
Transient Methods ◽  
State Analysis

AbstractThe results from a large number of single-hole packer tests in crystalline rock from three test sites in Sweden have been analysed statistically. Average hydraulic conductivity values for 25 m long test intervals along boreholes with a maximal length of about 700 m are used in this study. A comparison between steady state and transient analysis of the same test data has been performed.The mean vaule of the hydraulic conductivity determined from steady state analysis was found to be about two to three times higher compared to transient analysis. However, in some cases the steady state analysis resulted in 10 to 20 times higher values compared to the transient analysis. Such divergence between the two analysis methods may be caused by deviations from the assumed flow pattern, borehole skin effects and influence of hydraulic boundaries.

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