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Danilo Roberti Alves De Almeida - One of the best experts on this subject based on the ideXlab platform.
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contrasting Fire Damage and Fire susceptibility between seasonally flooded forest and upland forest in the central amazon using portable profiling lidar
Remote Sensing of Environment, 2016Co-Authors: Danilo Roberti Alves De Almeida, Bruce Walker Nelson, Juliana Schietti, Eric Bastos Gorgens, Angelica Faria De Resende, Scott C Stark, Ruben ValbuenaAbstract:Abstract Fire is an increasingly important agent of forest degradation in the Amazon, but little attention has been given to the susceptibility of seasonally flooded forests to Fire. Satellite images suggest that forests flooded seasonally by nutrient-poor black waters are more susceptible to Fire and may suffer greater Fire Damage than nearby upland forests. Reasons for this difference may include the presence of a root mat, more fine fuel as litter and a drier understory in the flooded forest. We investigated this difference in the field, hypothesizing that differences in the aboveground structure of the pre-burn forest can contribute to the difference in impacts of, and susceptibility to, Fires. We employed a portable profiling LiDAR (PPL), first to compare Damage between adjacent black water seasonally flooded and upland forests that were burned by the same Fire event, and to then assess pre-Fire canopy structure attributes known to affect Fire susceptibility. For both assessments, we used PPL-derived metrics of leaf area and vertical and horizontal variation in the structure of vegetation in the canopy. Four years after the Fire, the LiDAR metrics showed greater combined effects of high Damage and slow recovery in the seasonally flooded forest; reduction of total Leaf Area Index (LAI) after burning was only 10% for upland forest but was 71% in the flood forest. Compared to unburned upland, the canopy of unburned flood forest had structural differences that increase susceptibility to Fire, including drier microclimate. It had more gaps, a more open understory and a lower upper canopy. Small patches lacking canopy closure (LAI
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Fire Damage in seasonally flooded and upland forests of the central amazon
Biotropica, 2014Co-Authors: Angelica Faria De Resende, Bruce Walker Nelson, Bernardo M Flores, Danilo Roberti Alves De AlmeidaAbstract:ABSTRACT Neighboring upland and nutrient-poor seasonally flooded Amazon forests were penetrated by a fire in 2009, providing a natural com-parative experiment of fire Damage for these widespread forest types. In upland, only 16 10% ( 2 SEM) of stems and 21 8%of basal area were lost to fire, while seasonally flooded forest lost 59 13% of stems and 57 13% of basal area. Drier understorycontributes to greater flammability. Much of the area occupied by seasonally flooded woody vegetation (>11.5 percent of the Amazonregion) is vulnerable to fire due to high flammability and slow recovery.Abstract in Portuguese is available in the online version of this article. Key words: flammability; forest structure; igapo; litter layer; relative humidity; tropical forest. O VER 11.5 PERCENT OF THE AMAZON BASIN IS OCCUPIED BY SEASON-ALLY INUNDATED WOODY VEGETATION (Melack & Hess 2010).Seasonally flooded Amazon forests are home to a high diversityof trees (Wittmann et al. 2010), endemic invertebrates (Adis et al.2010) and frugivorous fish (Goulding et al. 1988, Correa et al.2007). Although inundated for much of the year, the litter layerof a low open-canopy floodplain forest of the upper Rio Negrocan ignite when relative humidity of the understory drops below65 percent (Uhl et al. 1988).Fire also penetrates closed-canopy floodplain forests of themiddle Rio Negro. Using field inventories and high-resolutionimages Flores et al. (2014) found average tree mortality of 90 per-cent from fires associated with droughts—much higher than themortality or percent of biomass loss reported after a first burn ofupland forests (Barbosa & Fearnside 1999, Cochrane et al. 1999,Barlow & Peres 2004). Amazon forests seasonally flooded bynutrient-poor waters have an aerated root mat and accumulationof leaf litter which together comprise a stock of fine, quick-dryingfuel two to three times larger than in nearby upland forest(Kauffmann et al. 1988, Dos Santos & Nelson 2013).These prior results suggest that flooded forest is less resistantto fire Damage than upland forest. However, no experiment has yetbeen performed comparing fire resistance of these two widespreadforest types. The Rio Negro provides few situations to compareflammability; river channels act as fire breaks between the two for-est types and ignition sources differ (e.g., fishermen’s campfires aremore abundant in the floodplain). A report by Nelson (2001) com-pared fire Damage between upland and floodplain forests in closeproximity and penetrated by the same fire, but relied only on visualinspection of satellite images and air photography.Here, we use a natural experiment to address the hypothesisthat given equal ignition opportunity and identical recent rainfallhistory, fire will cause greater Damage to undisturbed nutrient-poor flooded forest than undisturbed upland forest (H1). Oursecond hypothesis examines cause: The unburned flooded forestunderstory has more prolonged periods of flammability than theunburned upland forest understory (H2).South of the central sector of the Amazon River are exten-sive terraces 15–20 m above the present local high water level.Irion et al. (2010) interpret these as paleo-floodplains depositedduring Pleistocene interglacial periods, such as 110,000 years ago,when the Amazon River was slightly above its present relativelevel. During the final Pleistocene low sea stand the paleo-flood-plains became upland and were weakly incised by erosion, form-ing dense dendritic networks of shallow valleys. Post-Pleistocenesea level rise back-flooded the Amazon main stem and theseshallow incised valleys. Currently, they are seasonally inundatedby a 10 m amplitude annual flood pulse and are colonized bytrees tolerant to periodic inundation. Between the seasonallyflooded valleys, the paleo-floodplain terrace forms flat narrowinterfluves covered by flood intolerant upland tree species.For three reasons, fires on this landscape provide the idealnatural experiment to address H1. First, tree cover is continuousbetween the two forest types, with no intervening open water orerosional scarp to impede passage of fire. Second, the two foresttypes are spatially intercalated because of the dense network ofseasonally flooded valleys, allowing placement of all plots in closeproximity. As a result, sites can have identical pre-burn rainfalland equal ignition opportunity when fires course through the sea-sonally flooded valley forest (Fig. S1). Finally, because ignitionsources for both forest types (swidden fields and pastures) wereabsent over much of the area until recent decades, it is easy tofind forest that has burned only once.
Angelica Faria De Resende - One of the best experts on this subject based on the ideXlab platform.
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contrasting Fire Damage and Fire susceptibility between seasonally flooded forest and upland forest in the central amazon using portable profiling lidar
Remote Sensing of Environment, 2016Co-Authors: Danilo Roberti Alves De Almeida, Bruce Walker Nelson, Juliana Schietti, Eric Bastos Gorgens, Angelica Faria De Resende, Scott C Stark, Ruben ValbuenaAbstract:Abstract Fire is an increasingly important agent of forest degradation in the Amazon, but little attention has been given to the susceptibility of seasonally flooded forests to Fire. Satellite images suggest that forests flooded seasonally by nutrient-poor black waters are more susceptible to Fire and may suffer greater Fire Damage than nearby upland forests. Reasons for this difference may include the presence of a root mat, more fine fuel as litter and a drier understory in the flooded forest. We investigated this difference in the field, hypothesizing that differences in the aboveground structure of the pre-burn forest can contribute to the difference in impacts of, and susceptibility to, Fires. We employed a portable profiling LiDAR (PPL), first to compare Damage between adjacent black water seasonally flooded and upland forests that were burned by the same Fire event, and to then assess pre-Fire canopy structure attributes known to affect Fire susceptibility. For both assessments, we used PPL-derived metrics of leaf area and vertical and horizontal variation in the structure of vegetation in the canopy. Four years after the Fire, the LiDAR metrics showed greater combined effects of high Damage and slow recovery in the seasonally flooded forest; reduction of total Leaf Area Index (LAI) after burning was only 10% for upland forest but was 71% in the flood forest. Compared to unburned upland, the canopy of unburned flood forest had structural differences that increase susceptibility to Fire, including drier microclimate. It had more gaps, a more open understory and a lower upper canopy. Small patches lacking canopy closure (LAI
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Fire Damage in seasonally flooded and upland forests of the central amazon
Biotropica, 2014Co-Authors: Angelica Faria De Resende, Bruce Walker Nelson, Bernardo M Flores, Danilo Roberti Alves De AlmeidaAbstract:ABSTRACT Neighboring upland and nutrient-poor seasonally flooded Amazon forests were penetrated by a fire in 2009, providing a natural com-parative experiment of fire Damage for these widespread forest types. In upland, only 16 10% ( 2 SEM) of stems and 21 8%of basal area were lost to fire, while seasonally flooded forest lost 59 13% of stems and 57 13% of basal area. Drier understorycontributes to greater flammability. Much of the area occupied by seasonally flooded woody vegetation (>11.5 percent of the Amazonregion) is vulnerable to fire due to high flammability and slow recovery.Abstract in Portuguese is available in the online version of this article. Key words: flammability; forest structure; igapo; litter layer; relative humidity; tropical forest. O VER 11.5 PERCENT OF THE AMAZON BASIN IS OCCUPIED BY SEASON-ALLY INUNDATED WOODY VEGETATION (Melack & Hess 2010).Seasonally flooded Amazon forests are home to a high diversityof trees (Wittmann et al. 2010), endemic invertebrates (Adis et al.2010) and frugivorous fish (Goulding et al. 1988, Correa et al.2007). Although inundated for much of the year, the litter layerof a low open-canopy floodplain forest of the upper Rio Negrocan ignite when relative humidity of the understory drops below65 percent (Uhl et al. 1988).Fire also penetrates closed-canopy floodplain forests of themiddle Rio Negro. Using field inventories and high-resolutionimages Flores et al. (2014) found average tree mortality of 90 per-cent from fires associated with droughts—much higher than themortality or percent of biomass loss reported after a first burn ofupland forests (Barbosa & Fearnside 1999, Cochrane et al. 1999,Barlow & Peres 2004). Amazon forests seasonally flooded bynutrient-poor waters have an aerated root mat and accumulationof leaf litter which together comprise a stock of fine, quick-dryingfuel two to three times larger than in nearby upland forest(Kauffmann et al. 1988, Dos Santos & Nelson 2013).These prior results suggest that flooded forest is less resistantto fire Damage than upland forest. However, no experiment has yetbeen performed comparing fire resistance of these two widespreadforest types. The Rio Negro provides few situations to compareflammability; river channels act as fire breaks between the two for-est types and ignition sources differ (e.g., fishermen’s campfires aremore abundant in the floodplain). A report by Nelson (2001) com-pared fire Damage between upland and floodplain forests in closeproximity and penetrated by the same fire, but relied only on visualinspection of satellite images and air photography.Here, we use a natural experiment to address the hypothesisthat given equal ignition opportunity and identical recent rainfallhistory, fire will cause greater Damage to undisturbed nutrient-poor flooded forest than undisturbed upland forest (H1). Oursecond hypothesis examines cause: The unburned flooded forestunderstory has more prolonged periods of flammability than theunburned upland forest understory (H2).South of the central sector of the Amazon River are exten-sive terraces 15–20 m above the present local high water level.Irion et al. (2010) interpret these as paleo-floodplains depositedduring Pleistocene interglacial periods, such as 110,000 years ago,when the Amazon River was slightly above its present relativelevel. During the final Pleistocene low sea stand the paleo-flood-plains became upland and were weakly incised by erosion, form-ing dense dendritic networks of shallow valleys. Post-Pleistocenesea level rise back-flooded the Amazon main stem and theseshallow incised valleys. Currently, they are seasonally inundatedby a 10 m amplitude annual flood pulse and are colonized bytrees tolerant to periodic inundation. Between the seasonallyflooded valleys, the paleo-floodplain terrace forms flat narrowinterfluves covered by flood intolerant upland tree species.For three reasons, fires on this landscape provide the idealnatural experiment to address H1. First, tree cover is continuousbetween the two forest types, with no intervening open water orerosional scarp to impede passage of fire. Second, the two foresttypes are spatially intercalated because of the dense network ofseasonally flooded valleys, allowing placement of all plots in closeproximity. As a result, sites can have identical pre-burn rainfalland equal ignition opportunity when fires course through the sea-sonally flooded valley forest (Fig. S1). Finally, because ignitionsources for both forest types (swidden fields and pastures) wereabsent over much of the area until recent decades, it is easy tofind forest that has burned only once.
Bruce Walker Nelson - One of the best experts on this subject based on the ideXlab platform.
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contrasting Fire Damage and Fire susceptibility between seasonally flooded forest and upland forest in the central amazon using portable profiling lidar
Remote Sensing of Environment, 2016Co-Authors: Danilo Roberti Alves De Almeida, Bruce Walker Nelson, Juliana Schietti, Eric Bastos Gorgens, Angelica Faria De Resende, Scott C Stark, Ruben ValbuenaAbstract:Abstract Fire is an increasingly important agent of forest degradation in the Amazon, but little attention has been given to the susceptibility of seasonally flooded forests to Fire. Satellite images suggest that forests flooded seasonally by nutrient-poor black waters are more susceptible to Fire and may suffer greater Fire Damage than nearby upland forests. Reasons for this difference may include the presence of a root mat, more fine fuel as litter and a drier understory in the flooded forest. We investigated this difference in the field, hypothesizing that differences in the aboveground structure of the pre-burn forest can contribute to the difference in impacts of, and susceptibility to, Fires. We employed a portable profiling LiDAR (PPL), first to compare Damage between adjacent black water seasonally flooded and upland forests that were burned by the same Fire event, and to then assess pre-Fire canopy structure attributes known to affect Fire susceptibility. For both assessments, we used PPL-derived metrics of leaf area and vertical and horizontal variation in the structure of vegetation in the canopy. Four years after the Fire, the LiDAR metrics showed greater combined effects of high Damage and slow recovery in the seasonally flooded forest; reduction of total Leaf Area Index (LAI) after burning was only 10% for upland forest but was 71% in the flood forest. Compared to unburned upland, the canopy of unburned flood forest had structural differences that increase susceptibility to Fire, including drier microclimate. It had more gaps, a more open understory and a lower upper canopy. Small patches lacking canopy closure (LAI
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Fire Damage in seasonally flooded and upland forests of the central amazon
Biotropica, 2014Co-Authors: Angelica Faria De Resende, Bruce Walker Nelson, Bernardo M Flores, Danilo Roberti Alves De AlmeidaAbstract:ABSTRACT Neighboring upland and nutrient-poor seasonally flooded Amazon forests were penetrated by a fire in 2009, providing a natural com-parative experiment of fire Damage for these widespread forest types. In upland, only 16 10% ( 2 SEM) of stems and 21 8%of basal area were lost to fire, while seasonally flooded forest lost 59 13% of stems and 57 13% of basal area. Drier understorycontributes to greater flammability. Much of the area occupied by seasonally flooded woody vegetation (>11.5 percent of the Amazonregion) is vulnerable to fire due to high flammability and slow recovery.Abstract in Portuguese is available in the online version of this article. Key words: flammability; forest structure; igapo; litter layer; relative humidity; tropical forest. O VER 11.5 PERCENT OF THE AMAZON BASIN IS OCCUPIED BY SEASON-ALLY INUNDATED WOODY VEGETATION (Melack & Hess 2010).Seasonally flooded Amazon forests are home to a high diversityof trees (Wittmann et al. 2010), endemic invertebrates (Adis et al.2010) and frugivorous fish (Goulding et al. 1988, Correa et al.2007). Although inundated for much of the year, the litter layerof a low open-canopy floodplain forest of the upper Rio Negrocan ignite when relative humidity of the understory drops below65 percent (Uhl et al. 1988).Fire also penetrates closed-canopy floodplain forests of themiddle Rio Negro. Using field inventories and high-resolutionimages Flores et al. (2014) found average tree mortality of 90 per-cent from fires associated with droughts—much higher than themortality or percent of biomass loss reported after a first burn ofupland forests (Barbosa & Fearnside 1999, Cochrane et al. 1999,Barlow & Peres 2004). Amazon forests seasonally flooded bynutrient-poor waters have an aerated root mat and accumulationof leaf litter which together comprise a stock of fine, quick-dryingfuel two to three times larger than in nearby upland forest(Kauffmann et al. 1988, Dos Santos & Nelson 2013).These prior results suggest that flooded forest is less resistantto fire Damage than upland forest. However, no experiment has yetbeen performed comparing fire resistance of these two widespreadforest types. The Rio Negro provides few situations to compareflammability; river channels act as fire breaks between the two for-est types and ignition sources differ (e.g., fishermen’s campfires aremore abundant in the floodplain). A report by Nelson (2001) com-pared fire Damage between upland and floodplain forests in closeproximity and penetrated by the same fire, but relied only on visualinspection of satellite images and air photography.Here, we use a natural experiment to address the hypothesisthat given equal ignition opportunity and identical recent rainfallhistory, fire will cause greater Damage to undisturbed nutrient-poor flooded forest than undisturbed upland forest (H1). Oursecond hypothesis examines cause: The unburned flooded forestunderstory has more prolonged periods of flammability than theunburned upland forest understory (H2).South of the central sector of the Amazon River are exten-sive terraces 15–20 m above the present local high water level.Irion et al. (2010) interpret these as paleo-floodplains depositedduring Pleistocene interglacial periods, such as 110,000 years ago,when the Amazon River was slightly above its present relativelevel. During the final Pleistocene low sea stand the paleo-flood-plains became upland and were weakly incised by erosion, form-ing dense dendritic networks of shallow valleys. Post-Pleistocenesea level rise back-flooded the Amazon main stem and theseshallow incised valleys. Currently, they are seasonally inundatedby a 10 m amplitude annual flood pulse and are colonized bytrees tolerant to periodic inundation. Between the seasonallyflooded valleys, the paleo-floodplain terrace forms flat narrowinterfluves covered by flood intolerant upland tree species.For three reasons, fires on this landscape provide the idealnatural experiment to address H1. First, tree cover is continuousbetween the two forest types, with no intervening open water orerosional scarp to impede passage of fire. Second, the two foresttypes are spatially intercalated because of the dense network ofseasonally flooded valleys, allowing placement of all plots in closeproximity. As a result, sites can have identical pre-burn rainfalland equal ignition opportunity when fires course through the sea-sonally flooded valley forest (Fig. S1). Finally, because ignitionsources for both forest types (swidden fields and pastures) wereabsent over much of the area until recent decades, it is easy tofind forest that has burned only once.
Ruben Valbuena - One of the best experts on this subject based on the ideXlab platform.
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contrasting Fire Damage and Fire susceptibility between seasonally flooded forest and upland forest in the central amazon using portable profiling lidar
Remote Sensing of Environment, 2016Co-Authors: Danilo Roberti Alves De Almeida, Bruce Walker Nelson, Juliana Schietti, Eric Bastos Gorgens, Angelica Faria De Resende, Scott C Stark, Ruben ValbuenaAbstract:Abstract Fire is an increasingly important agent of forest degradation in the Amazon, but little attention has been given to the susceptibility of seasonally flooded forests to Fire. Satellite images suggest that forests flooded seasonally by nutrient-poor black waters are more susceptible to Fire and may suffer greater Fire Damage than nearby upland forests. Reasons for this difference may include the presence of a root mat, more fine fuel as litter and a drier understory in the flooded forest. We investigated this difference in the field, hypothesizing that differences in the aboveground structure of the pre-burn forest can contribute to the difference in impacts of, and susceptibility to, Fires. We employed a portable profiling LiDAR (PPL), first to compare Damage between adjacent black water seasonally flooded and upland forests that were burned by the same Fire event, and to then assess pre-Fire canopy structure attributes known to affect Fire susceptibility. For both assessments, we used PPL-derived metrics of leaf area and vertical and horizontal variation in the structure of vegetation in the canopy. Four years after the Fire, the LiDAR metrics showed greater combined effects of high Damage and slow recovery in the seasonally flooded forest; reduction of total Leaf Area Index (LAI) after burning was only 10% for upland forest but was 71% in the flood forest. Compared to unburned upland, the canopy of unburned flood forest had structural differences that increase susceptibility to Fire, including drier microclimate. It had more gaps, a more open understory and a lower upper canopy. Small patches lacking canopy closure (LAI
Luc Taerwe - One of the best experts on this subject based on the ideXlab platform.
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Ultrasonic pulse velocity to assess the Fire Damage of concrete
2012Co-Authors: Emmanuel Annerel, Luc TaerweAbstract:During a Fire, concrete structures behave in most cases very well. Therefore, it could be of economic interest to repair the Damaged structure, as costs for demolition and rebuilding can be avoided and the building can be reused faster. The extent of Damage can be assessed with a visual inspection, aided by non destructive techniques. This paper describes ultrasonic pulse velocity as such a method to assess the Fire Damage. Differences in velocity are expected as function of temperature, since cracks will occur in the cement matrix and in the interfacial transition zone due to thermal incompatibilities of the concrete constituents. Also, an increase of the porosity can be found, because of depletion of the hydration products. Furthermore, due to decrease of flexural and shear strength, structural cracks will occur. UPV can be used as a non destructive technique to assess the Fire Damage near the concrete surface.
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methods to quantify the colour development of concrete exposed to Fire
Construction and Building Materials, 2011Co-Authors: Emmanuel Annerel, Luc TaerweAbstract:Abstract In this paper two techniques are discussed to measure the colour of concrete samples after Fire exposure, namely a spectrophotometer and a calibrated flatbed scanner. These techniques are used to trace the temperature history of the concrete, from which the corresponding Fire Damage can be assessed. A spectrophotometer allows to measure colours in a fast and device independent way, resulting in absolute colours usable as a reference in both laboratory and field explorations. A flatbed scanner is less portable, but can be coupled to image analysis software by which focus is possible solely on the cement matrix. The alteration of the colour of traditional and self-compacting concrete is studied in both HSI and CIE Lab colour space. With increasing temperature not only a shift to red is considered, but also the development of a colour path.