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Donald A Falk - One of the best experts on this subject based on the ideXlab platform.

  • Macroanatomy and compartmentalization of recent Fire Scars in three North American conifers
    Canadian Journal of Forest Research, 2016
    Co-Authors: Kevin T. Smith, Estelle Arbellay, Donald A Falk, Elaine Kennedy Sutherland
    Abstract:

    Fire Scars are initiated by cambial necrosis caused by localized lethal heating of the tree stem. Scars develop as part of the linked survival processes of compartmentalization and wound closure. The position of Scars within dated tree ring series is the basis for dendrochronological reconstruction of Fire history. Macroanatomical features were described for western larch (Larix occidentalis Nutt.), ponderosa pine (Pinus ponderosa Douglas ex P. Lawson & C. Lawson), and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) injured by Fire in 2003 and harvested in 2011 at the Lolo National Forest near Missoula, Montana, USA. Bark scorch did not necessarily indicate the formation of a scar. Wound-initiated discoloration inward from the scar face was bounded tangentially by reaction zones. In western larch, the transition between earlywood and latewood was much less abrupt in woundwood rings than in rings formed the same year but not associated with a scar. Wood formed the year after injury contained tangential ...

  • Resin duct size and density as ecophysiological traits in Fire Scars of Pseudotsuga menziesii and Larix occidentalis
    Annals of botany, 2014
    Co-Authors: Estelle Arbellay, Elaine Kennedy Sutherland, Kevin T. Smith, Markus Stoffel, Donald A Falk
    Abstract:

    Resin ducts (RDs) are features present in most conifer species as defence structures against pests and pathogens; however, little is known about RD expression in trees following Fire injury. This study investigates changes in RD size and density in Fire Scars of Douglas fir (Pseudotsuga menziesii) and western larch (Larix occidentalis) as a means to evaluate the ecophysiological significance of traumatic resinosis for tree defence and survival.

  • changes in tracheid and ray traits in Fire Scars of north american conifers and their ecophysiological implications
    Annals of Botany, 2014
    Co-Authors: Estelle Arbellay, Elaine Kennedy Sutherland, Kevin T. Smith, Markus Stoffel, Donald A Falk
    Abstract:

    †BackgroundandAims Fire Scars have been widely used as proxies for the reconstruction of Fire history; however, little is known about the impact of Fire injury on wood anatomy. This study investigates changes in tracheid and ray traits in Fire Scars of Douglas fir (Pseudotsuga menziesii), western larch (Larix occidentalis) and ponderosa pine (Pinus ponderosa), and discusses their ecophysiological implications for tree recovery from Fire. †Methods Transverse and tangential microsections were prepared for light microscopy and image analysis. Measurements of tracheids and rays were made in the three spatial dimensions: axially (at different section heights), radially (in different rings) and tangentially (with increasing distance from the wound margin). †KeyResults Changes were strongest in the first year after Fire injury, with a decrease in tracheid size (by 25 ‐30 %) and an increase in tracheid density (by 21 ‐53 %) for the three species. In addition, an increase in ray size (by 5 ‐27 %) and an increase in ray density (by 19‐ 36 %) were found inP.menziesii andL.occidentalis. Changes were comparable along the Fire-injured stem and were often most marked close to the Fire scar. †Conclusions The differentiation after Fire injury of narrower and more numerous tracheids expresses a trade-off between hydraulic safety and hydraulic efficiency, while that of larger and more numerous rays serves compartmentalization and wound closure, mechanical strength and defence responses. Pinus ponderosa does not generally produce more ray tissue after Fire injury and thus appears to be more adapted to Fire.

  • Macroanatomy of compartmentalization in Fire Scars of three western conifers
    2013
    Co-Authors: Kevin T. Smith, Estelle Arbellay, Elaine Kennedy Sutherland, Markus Stoffel, Donald A Falk
    Abstract:

    Fire Scars are visible evidence of compartmentalization and closure processes that contribute to tree survival after Fire injury. Preliminary observations of dissected Fire Scars from trees injured within the last decade showed centripetal development of wound-initiated discoloration (WID) through 2-3 decades of former sapwood in Larix occidentalis and Pseudotsuga menziesii. Although the WID reached and was apparently confluent with the visually similar heartwood, WID lacked the decay and insect resistance characteristics of heartwood. In contrast, development of WID in Pinus ponderosa, was limited to fewer than 5 rings of former sapwood with healthy sapwood retained between the WID and heartwood. The healthy sapwood has the potential to actively resist the spread of infection and further loss of wood function. For wound closure, all three species produced wide rings of woundwood from the margin of the killed vascular cambium in the growing season following Fire injury.

  • spatial and temporal corroboration of a Fire scar based Fire history in a frequently burned ponderosa pine forest
    Ecological Applications, 2010
    Co-Authors: Calvin A Farris, Donald A Falk, Christopher H. Baisan, Stephen R Yool, Thomas W. Swetnam
    Abstract:

    Fire Scars are used widely to reconstruct historical Fire regime parameters in forests around the world. Because Fire Scars provide incomplete records of past Fire occurrence at discrete points in space, inferences must be made to reconstruct Fire frequency and extent across landscapes using spatial networks of Fire-scar samples. Assessing the relative accuracy of Fire-scar Fire history reconstructions has been hampered due to a lack of empirical comparisons with independent Fire history data sources. We carried out such a comparison in a 2780-ha ponderosa pine forest on Mica Mountain in southern Arizona (USA) for the time period 1937–2000. Using documentary records of Fire perimeter maps and ignition locations, we compared reconstructions of key spatial and temporal Fire regime parameters developed from documentary Fire maps and independently collected Fire-scar data (n = 60 plots). We found that Fire-scar data provided spatially representative and complete inventories of all major Fire years (>100 ha) i...

B. Wyatt - One of the best experts on this subject based on the ideXlab platform.

  • Forest Fire scar detection in the boreal forest with multitemporal SPOT-VEGETATION data
    IEEE Transactions on Geoscience and Remote Sensing, 2003
    Co-Authors: F. Gerard, Heiko Balzter, S. Plummer, Richard A. Wadsworth, A. Ferreruela Sanfeliu, L. Iliffe, B. Wyatt
    Abstract:

    Disturbance events, such as Fire, have a major impact on boreal forest dynamics, succession, and the global carbon cycle. Methods using satellite imagery are well established for detecting forest Fires in real time and mapping the burned area (Fire Scars) within one year of the Fire. This paper focuses on the detection of older Fire disturbance-regeneration patterns in the boreal forests of Canada. Previous work found that shortwave-infrared image segmentation proved particularly good at creating uniform regions that were easy to associate with Fire Scars. Our findings suggest it is possible to detect Fire Scars up to ten years old using SPOT-VEGETATION data from a single year and that the use of a vegetation index based on near- and shortwave-infrared reflectance is critical to this success. We demonstrate how the use of short-term multitemporal imagery can enhance segmentation results and present a threshold-based procedure for a posteriori identification of Fire scar segments. The resulting Fire scar probability map showed a good correspondence with records of Fire Scars mapped by the Canadian Forest Service for 1980-1992 and "hot spots" from the FireM3 Information System for 1994-1998.

Markus Stoffel - One of the best experts on this subject based on the ideXlab platform.

  • Fire-scarred fossil tree from the Late Triassic shows a pre-Fire drought signal.
    Scientific reports, 2020
    Co-Authors: Bruce A. Byers, Lucía Desoto, Dan S. Chaney, Sidney R. Ash, Anya B. Byers, Jonathan B. Byers, Markus Stoffel
    Abstract:

    Exploring features of wood anatomy associated with Fire Scars found on fossil tree trunks is likely to increase our knowledge of the environmental and ecological processes that occurred in ancient forests and of the role of Fire as an evolutionary force. In Petrified Forest National Park, Arizona, where Late Triassic fossil trees are exposed, we found 13 examples of fossil logs with external features resembling modern Fire Scars. One specimen with the unambiguous external features of a Fire scar was collected for analysis of its fossilized wood. A light-colored band composed of compressed and distorted tracheids was associated with the scarring event. Cell lumen diameter and cell wall thickness in the pre-scarring fossilized wood show a response similar to that described in modern trees experiencing drought conditions. Tracheids in the post-scarring wood are initially smaller, and then become larger than average following a recovery period, as is often observed in modern conifers following Fire. The responses in external morphology and wood anatomy to drought and Fire were similar to those of some modern trees and support the view that some forests may have experienced conditions favoring the evolution of Fire-adapted traits for more than 200 million years.

  • Resin duct size and density as ecophysiological traits in Fire Scars of Pseudotsuga menziesii and Larix occidentalis
    Annals of botany, 2014
    Co-Authors: Estelle Arbellay, Elaine Kennedy Sutherland, Kevin T. Smith, Markus Stoffel, Donald A Falk
    Abstract:

    Resin ducts (RDs) are features present in most conifer species as defence structures against pests and pathogens; however, little is known about RD expression in trees following Fire injury. This study investigates changes in RD size and density in Fire Scars of Douglas fir (Pseudotsuga menziesii) and western larch (Larix occidentalis) as a means to evaluate the ecophysiological significance of traumatic resinosis for tree defence and survival.

  • changes in tracheid and ray traits in Fire Scars of north american conifers and their ecophysiological implications
    Annals of Botany, 2014
    Co-Authors: Estelle Arbellay, Elaine Kennedy Sutherland, Kevin T. Smith, Markus Stoffel, Donald A Falk
    Abstract:

    †BackgroundandAims Fire Scars have been widely used as proxies for the reconstruction of Fire history; however, little is known about the impact of Fire injury on wood anatomy. This study investigates changes in tracheid and ray traits in Fire Scars of Douglas fir (Pseudotsuga menziesii), western larch (Larix occidentalis) and ponderosa pine (Pinus ponderosa), and discusses their ecophysiological implications for tree recovery from Fire. †Methods Transverse and tangential microsections were prepared for light microscopy and image analysis. Measurements of tracheids and rays were made in the three spatial dimensions: axially (at different section heights), radially (in different rings) and tangentially (with increasing distance from the wound margin). †KeyResults Changes were strongest in the first year after Fire injury, with a decrease in tracheid size (by 25 ‐30 %) and an increase in tracheid density (by 21 ‐53 %) for the three species. In addition, an increase in ray size (by 5 ‐27 %) and an increase in ray density (by 19‐ 36 %) were found inP.menziesii andL.occidentalis. Changes were comparable along the Fire-injured stem and were often most marked close to the Fire scar. †Conclusions The differentiation after Fire injury of narrower and more numerous tracheids expresses a trade-off between hydraulic safety and hydraulic efficiency, while that of larger and more numerous rays serves compartmentalization and wound closure, mechanical strength and defence responses. Pinus ponderosa does not generally produce more ray tissue after Fire injury and thus appears to be more adapted to Fire.

  • Macroanatomy of compartmentalization in Fire Scars of three western conifers
    2013
    Co-Authors: Kevin T. Smith, Estelle Arbellay, Elaine Kennedy Sutherland, Markus Stoffel, Donald A Falk
    Abstract:

    Fire Scars are visible evidence of compartmentalization and closure processes that contribute to tree survival after Fire injury. Preliminary observations of dissected Fire Scars from trees injured within the last decade showed centripetal development of wound-initiated discoloration (WID) through 2-3 decades of former sapwood in Larix occidentalis and Pseudotsuga menziesii. Although the WID reached and was apparently confluent with the visually similar heartwood, WID lacked the decay and insect resistance characteristics of heartwood. In contrast, development of WID in Pinus ponderosa, was limited to fewer than 5 rings of former sapwood with healthy sapwood retained between the WID and heartwood. The healthy sapwood has the potential to actively resist the spread of infection and further loss of wood function. For wound closure, all three species produced wide rings of woundwood from the margin of the killed vascular cambium in the growing season following Fire injury.

Florian Siegert - One of the best experts on this subject based on the ideXlab platform.

  • Backscatter change on Fire Scars in Siberian boreal forests in ENVISAT ASAR wide-swath images
    IEEE Geoscience and Remote Sensing Letters, 2006
    Co-Authors: Shengli Huang, Florian Siegert
    Abstract:

    The objective of this letter was to investigate the performance of the C-band Advanced Synthetic Aperture Radar (ASAR) instrument onboard the European ENVISAT satellite for mapping Fire Scars in boreal forest ecosystems. The Wide Swath Mode (WSM) of the cloud and haze-penetrating ASAR instrument with a spatial resolution of 150 m would be ideal to support nearly real-time Fire monitoring and impact assessment over the vast and sparsely populated circumpolar forest belt. We found that: (1) the ASAR WSM backscatter signal was sensitive to Fire disturbance; (2) the backscatter change correlated mainly with snow-melt and rainfall; and (3) the backscatter varied as a function of the incidence angle with a higher backscatter occurring at shallower incidence angles. The results suggest ASAR WSM data could be used to support operational Fire impact monitoring in boreal forests of Siberia. Multitemporal datasets are required because environmental conditions strongly influence the backscatter signal.

Heiko Balzter - One of the best experts on this subject based on the ideXlab platform.

  • A statistical model linking Siberian forest Fire Scars with early summer rainfall anomalies
    Geophysical Research Letters, 2006
    Co-Authors: Tim E. Jupp, Christopher M. Taylor, Heiko Balzter, Charles George
    Abstract:

    [1] Forest Fires in Siberia have a significant effect on the global carbon balance. It is therefore of interest to study the environmental factors that may be responsible for their variability. Here we examine variability in the annual number of forest Fire Scars at a spatial scale of 2.5°. This is decomposed statistically into a spatio–temporal component correlated with low summer rainfall, a spatial component correlated with population density and a temporal component correlated with the Arctic Oscillation. Data come from ten years of satellite–derived data, incorporating both the number of forest Fire Scars and monthly rainfall. The expected number of Fire Scars halves for each additional 0.35 mm per day of rainfall in the period April–July. Our findings may prove useful in parameterising both Fire models within climate simulations and Fire warning systems based on numerical weather predictions of regional dry anomalies.

  • Forest Fire scar detection in the boreal forest with multitemporal SPOT-VEGETATION data
    IEEE Transactions on Geoscience and Remote Sensing, 2003
    Co-Authors: F. Gerard, Heiko Balzter, S. Plummer, Richard A. Wadsworth, A. Ferreruela Sanfeliu, L. Iliffe, B. Wyatt
    Abstract:

    Disturbance events, such as Fire, have a major impact on boreal forest dynamics, succession, and the global carbon cycle. Methods using satellite imagery are well established for detecting forest Fires in real time and mapping the burned area (Fire Scars) within one year of the Fire. This paper focuses on the detection of older Fire disturbance-regeneration patterns in the boreal forests of Canada. Previous work found that shortwave-infrared image segmentation proved particularly good at creating uniform regions that were easy to associate with Fire Scars. Our findings suggest it is possible to detect Fire Scars up to ten years old using SPOT-VEGETATION data from a single year and that the use of a vegetation index based on near- and shortwave-infrared reflectance is critical to this success. We demonstrate how the use of short-term multitemporal imagery can enhance segmentation results and present a threshold-based procedure for a posteriori identification of Fire scar segments. The resulting Fire scar probability map showed a good correspondence with records of Fire Scars mapped by the Canadian Forest Service for 1980-1992 and "hot spots" from the FireM3 Information System for 1994-1998.