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Jean Claude Ruel - One of the best experts on this subject based on the ideXlab platform.
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Windthrow dynamics in boreal ontario a simulation of the vulnerability of several stand types across a range of wind speeds
Forests, 2017Co-Authors: Kenneth A Anyomi, Stephen J. Mitchell, Ajith H Perera, Jean Claude RuelAbstract:In Boreal North America, management approaches inspired by the variability in natural disturbances are expected to produce more resilient forests. Wind storms are recurrent within Boreal Ontario. The objective of this study was to simulate wind damage for common Boreal forest types for regular as well as extreme wind speeds. The ForestGALES_BC Windthrow prediction model was used for these simulations. Input tree-level data were derived from permanent sample plot (PSP) data provided by the Ontario Ministry of Natural Resources. PSPs were assigned to one of nine stand types: Balsam fir-, Jack pine-, Black spruce-, and hardwood-dominated stands, and, Jack pine-, spruce-, conifer-, hardwood-, and Red and White pine-mixed species stands. Morphological and biomechanical parameters for the major tree species were obtained from the literature. At 5 m/s, predicted Windthrow ranged from 0 to 20%, with damage increasing to 2 to 90% for winds of 20 m/s and to 10 to 100% for winds of 40 m/s. Windthrow varied by forest stand type, with lower vulnerability within hardwoods. This is the first study to provide such broad simulations of Windthrow vulnerability data for Boreal North America, and we believe this will benefit policy decisions regarding risk management and forest planning.
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potential impact of climate change on the risk of Windthrow in eastern canada s forests
Climatic Change, 2017Co-Authors: Christian Saad, Jean Claude Ruel, Yan Boulanger, Marilou Beaudet, Philippe Gachon, Sylvie GauthierAbstract:Abstract Climate change is likely to affect Windthrow risks at northern latitudes by potentially changing high wind probabilities and soil frost duration. Here, we evaluated the effect of climate change on Windthrow risk in eastern Canada’s balsam fir (Abies balsamea [L.] Mill.) forests using a methodology that accounted for changes in both wind speed and soil frost duration. We used wind speed and soil temperature projections at the regional scale from the CRCM5 regional climate model (RCM) driven by the CanESM2 global climate model (GCM) under two representative concentration pathways (RCP4.5, RCP8.5), for a baseline (1976–2005) and two future periods (2041–2070, 2071–2100). A hybrid mechanistic model (ForestGALES) that considers species resistance to uprooting and wind speed distribution was used to calculate Windthrow risk. An increased risk of Windthrow (3 to 30%) was predicted for the future mainly due to an increased duration of unfrozen soil conditions (by up to 2 to 3 months by the end of the twenty-first century under RCP8.5). In contrast, wind speed did not vary markedly with a changing climate. Strong regional variations in wind speeds translated into regional differences in Windthrow risk, with the easternmost region (Atlantic provinces) having the strongest winds and the highest Windthrow risk. Because of the inherent uncertainties associated with climate change projections, especially regarding wind climate, further research is required to assess Windthrow risk from the optimum combination of RCM/GCM ensemble simulations.
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Potential impact of climate change on the risk of Windthrow in eastern Canada’s forests
Climatic Change, 2017Co-Authors: Christian Saad, Jean Claude Ruel, Yan Boulanger, Marilou Beaudet, Philippe Gachon, Sylvie GauthierAbstract:Abstract Climate change is likely to affect Windthrow risks at northern latitudes by potentially changing high wind probabilities and soil frost duration. Here, we evaluated the effect of climate change on Windthrow risk in eastern Canada’s balsam fir (Abies balsamea [L.] Mill.) forests using a methodology that accounted for changes in both wind speed and soil frost duration. We used wind speed and soil temperature projections at the regional scale from the CRCM5 regional climate model (RCM) driven by the CanESM2 global climate model (GCM) under two representative concentration pathways (RCP4.5, RCP8.5), for a baseline (1976–2005) and two future periods (2041–2070, 2071–2100). A hybrid mechanistic model (ForestGALES) that considers species resistance to uprooting and wind speed distribution was used to calculate Windthrow risk. An increased risk of Windthrow (3 to 30%) was predicted for the future mainly due to an increased duration of unfrozen soil conditions (by up to 2 to 3 months by the end of the twenty-first century under RCP8.5). In contrast, wind speed did not vary markedly with a changing climate. Strong regional variations in wind speeds translated into regional differences in Windthrow risk, with the easternmost region (Atlantic provinces) having the strongest winds and the highest Windthrow risk. Because of the inherent uncertainties associated with climate change projections, especially regarding wind climate, further research is required to assess Windthrow risk from the optimum combination of RCM/GCM ensemble simulations.
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Modeling Windthrow at Stand and Landscape Scales
Simulation Modeling of Forest Landscape Disturbances, 2015Co-Authors: Stephen J. Mitchell, Jean Claude RuelAbstract:Windthrow results when the wind loads acting on individual trees exceed their stem or anchorage resistance, leading to stem breakage or uprooting. While recurrent Windthrow is an important natural disturbance process, it also affects management planning, and can pose a threat to human safety and infrastructure. Empirical approaches to Windthrow susceptibility modeling can represent the full range of site, stand, and management conditions across windy landscapes, but provide limited insights into associated mechanisms and are of unknown accuracy in locations or scenarios not represented in the underlying observational data sets. Hybrid empirical–mechanistic approaches provide useful frameworks for integrating knowledge of component processes, but are simplified representations of the biology and mechanics of Windthrow and of the range of site and stand conditions within which Windthrow occurs. Both empirical and hybrid-mechanistic models have been integrated with forest inventories and growth and yield models within geographic information system (GIS)-based decision support systems that enable researchers to evaluate contrasting management and climate scenarios. However, these models are not yet available in formats that enable easy use by practitioners. Hybrid-mechanistic models could be improved by better representation of the interaction between wind and canopies and among trees, and the process of damage propagation during storms. As well, the models need to be validated for sites that better reflect the range of stand conditions and management regimes in forested landscapes. Wide availability of high-resolution satellite images for change detection, high-resolution spatial weather data sets, and LiDAR for characterizing terrain, soil drainage, and stand structure set the stage for rapid improvement in landscape-scale modeling of Windthrow with both empirical and hybrid-mechanistic approaches.
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Effects of post-Windthrow salvage logging on microsites, plant composition and regeneration
Applied Vegetation Science, 2013Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie Gauthier, Louis De Grandpré, Chris J. PetersonAbstract:AbstractQuestions: How does Windthrow influence plant diversity and composition aswell as regeneration and microsite characteristics? What are the consequencesofpost-Windthrowsalvageloggingonthesekeyattributes?Location:Easternblackspruce–mossforest,Quebec,Canada.Methods:Atotalof92plotsweresampled,eachwitharadiusof11.28 m;49ofthese plots were salvaged while 43 were unsalvaged. Regeneration density,plantdiversityandseedbedswerecharacterized.Wetestedtheeffectofmicroto-pography and Windthrow severity on species richness and Shannon diversityindex for salvaged and unsalvaged Windthrows using a mixed model. Partialredundancyanalysis(RDA)determinedwhichenvironmentalandstandcharac-teristicsweremostimportantinexplainingdifferencesinplantspeciesandforestfloortypesamongthetreatments.Theeffectsof treatments(salvaged and unsal-vagedWindthrows),microtopographyattributes,Windthrowseverityandregen-eration species on seedling and sapling abundance were tested using a linearmixedmodel.Results:SalvagedWindthrow,withalargeproportionofskidtrails,deadmossesand Sphagnum, had a lower degree of seedbed heterogeneity. Also, some under-storey species present in the unsalvaged ecosystem were absent from the sal-vaged Windthrow. Sphagnum and other moss species were clearly associatedwith the unsalvaged treatment. White birches were positively associated withmoundmicrotopographyintheunsalvagedWindthrow.Conclusion: From an ecosystem-based forest management perspective, naturalpost-Windthrow understorey conditions and microsite heterogeneity can be inpart maintained in salvaged cut blocks by incorporating retention patches thatinclude downed and standing dead wood and living trees of diverse sizes. Thesestepsshouldfavourplantregenerationandaugmentdiversityforsalvageloggingafterwinddisturbance.IntroductionIn many parts of the world, major disturbance episodesoften lead to salvage logging (often called sanitary loggingin Europe; Lindenmayer et al. 2004, 2008). Functionally,salvage logging can be distinguished from other harvestoperations in that, with salvaging after natural distur-bance, the ecosystem is subjected to two sequential distur-bances within a short period (Lindenmayer et al. 2008).Peterson & Leach (2008) suggest that multiple disturbanceimpacts need to be understood on the basis of cumulativeseverity. Indeed, recent conceptual advances (e.g. the cuspmodel of Frelich & Reich 1999; the three-axis model ofRoberts 2004, 2007) have begun to address the potentialfor multiple disturbances to change the trajectory of com-munity development, sometimes in undesirable directions(Paine et al. 1998). Because of the potential for thecombined severity of natural disturbance followed bysalvaging to yield unwanted ‘ecological surprises’ (Paineet al. 1998), guidelines are needed for the planning of
Stephen J. Mitchell - One of the best experts on this subject based on the ideXlab platform.
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Windthrow dynamics in boreal ontario a simulation of the vulnerability of several stand types across a range of wind speeds
Forests, 2017Co-Authors: Kenneth A Anyomi, Stephen J. Mitchell, Ajith H Perera, Jean Claude RuelAbstract:In Boreal North America, management approaches inspired by the variability in natural disturbances are expected to produce more resilient forests. Wind storms are recurrent within Boreal Ontario. The objective of this study was to simulate wind damage for common Boreal forest types for regular as well as extreme wind speeds. The ForestGALES_BC Windthrow prediction model was used for these simulations. Input tree-level data were derived from permanent sample plot (PSP) data provided by the Ontario Ministry of Natural Resources. PSPs were assigned to one of nine stand types: Balsam fir-, Jack pine-, Black spruce-, and hardwood-dominated stands, and, Jack pine-, spruce-, conifer-, hardwood-, and Red and White pine-mixed species stands. Morphological and biomechanical parameters for the major tree species were obtained from the literature. At 5 m/s, predicted Windthrow ranged from 0 to 20%, with damage increasing to 2 to 90% for winds of 20 m/s and to 10 to 100% for winds of 40 m/s. Windthrow varied by forest stand type, with lower vulnerability within hardwoods. This is the first study to provide such broad simulations of Windthrow vulnerability data for Boreal North America, and we believe this will benefit policy decisions regarding risk management and forest planning.
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Modeling Windthrow at Stand and Landscape Scales
Simulation Modeling of Forest Landscape Disturbances, 2015Co-Authors: Stephen J. Mitchell, Jean Claude RuelAbstract:Windthrow results when the wind loads acting on individual trees exceed their stem or anchorage resistance, leading to stem breakage or uprooting. While recurrent Windthrow is an important natural disturbance process, it also affects management planning, and can pose a threat to human safety and infrastructure. Empirical approaches to Windthrow susceptibility modeling can represent the full range of site, stand, and management conditions across windy landscapes, but provide limited insights into associated mechanisms and are of unknown accuracy in locations or scenarios not represented in the underlying observational data sets. Hybrid empirical–mechanistic approaches provide useful frameworks for integrating knowledge of component processes, but are simplified representations of the biology and mechanics of Windthrow and of the range of site and stand conditions within which Windthrow occurs. Both empirical and hybrid-mechanistic models have been integrated with forest inventories and growth and yield models within geographic information system (GIS)-based decision support systems that enable researchers to evaluate contrasting management and climate scenarios. However, these models are not yet available in formats that enable easy use by practitioners. Hybrid-mechanistic models could be improved by better representation of the interaction between wind and canopies and among trees, and the process of damage propagation during storms. As well, the models need to be validated for sites that better reflect the range of stand conditions and management regimes in forested landscapes. Wide availability of high-resolution satellite images for change detection, high-resolution spatial weather data sets, and LiDAR for characterizing terrain, soil drainage, and stand structure set the stage for rapid improvement in landscape-scale modeling of Windthrow with both empirical and hybrid-mechanistic approaches.
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testing of windfirm forestgales_bc a hybrid mechanistic model for predicting Windthrow in partially harvested stands
Forestry, 2013Co-Authors: Kenneth E. Byrne, Stephen J. MitchellAbstract:Windthrow is a common problem in forest management, particularly in areas exposed by recent harvesting or thinning. A hybrid-mechanistic model, WindFIRM/ForestGALES_BC, which builds upon the original ForestGALES, was developed to quantify component Windthrow processes for individual trees in heterogeneous stands. The objectives of this work are to improve Windthrow predictions at the tree level, represent the spatial patterns of Windthrow and build a platform upon which new functions could be added in the future to improve the veracity of the model. This model accounts for irregular openings and is able to simulate the propagation of Windthrow during storm events. Above canopy wind speed and direction are specified by the user or derived from spatial datasets. WindFIRM/ForestGALES_BC is integrated with a growth and yield model, TASS (Tree and Stand Simulator), which supplies spatial tree-lists. WindFIRM/ForestGALES_BC was tested using field plot data from the STEMS (Silvicultural Treatments for Ecosystem Management in the Sayward) research installation on Vancouver Island. The pattern of simulated Windthrow is consistent with patterns observed in the field. Relative damage rates across tree size classes are also consistent with field plot data. Further refinements to WindFIRM/ForestGALES_BC which accounts for Windthrow factors such as tree acclimation and resistance functions which account for site variability related to soils and root structure are suggested to improve predictions. However, the current model still provides insights into the consequences of cutblock design, and is a flexible platform for integration of new research on Windthrow component processes.
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Testing of WindFIRM/ForestGALES_BC: A hybrid-mechanistic model for predicting Windthrow in partially harvested stands
Forestry, 2012Co-Authors: Kenneth E. Byrne, Stephen J. MitchellAbstract:Windthrow is a common problem in forest management, particularly in areas exposed by recent harvesting or thinning. A hybrid-mechanistic model, WindFIRM/ForestGALES_BC, which builds upon the original ForestGALES, was developed to quantify component Windthrow processes for individual trees in heterogeneous stands. The objectives of this work are to improve Windthrow predictions at the tree level, represent the spatial patterns of Windthrow and build a platform upon which new functions could be added in the future to improve the veracity of the model. This model accounts for irregular openings and is able to simulate the propagation of Windthrow during storm events. Above canopy wind speed and direction are specified by the user or derived from spatial datasets. WindFIRM/ForestGALES_BC is integrated with a growth and yield model, TASS (Tree and Stand Simulator), which supplies spatial tree-lists. WindFIRM/ForestGALES_BC was tested using field plot data from the STEMS (Silvicultural Treatments for Ecosystem Management in the Sayward) research installation on Vancouver Island. The pattern of simulated Windthrow is consistent with patterns observed in the field. Relative damage rates across tree size classes are also consistent with field plot data. Further refinements to WindFIRM/ForestGALES_BC which accounts for Windthrow factors such as tree acclimation and resistance functions which account for site variability related to soils and root structure are suggested to improve predictions. However, the current model still provides insights into the consequences of cutblock design, and is a flexible platform for integration of new research on Windthrow component processes.
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post harvest Windthrow and recruitment of large woody debris in riparian buffers on vancouver island
European Journal of Forest Research, 2012Co-Authors: Devesh Bahuguna, Stephen J. Mitchell, Grant R NishioAbstract:Large woody debris (LWD) provides structural complexity to small streams. Riparian buffers are intended to provide long-term vegetation cover and supplies of LWD, but post-harvest Windthrow often occurs. To evaluate the impacts of Windthrow in riparian buffers and identify the components for a small stream LWD recruitment model, we sampled 26 streams in immature and older stands in wind-exposed areas of southwestern and northern Vancouver Island. These treed buffer strips had been exposed following clearcut harvest of adjacent timber on both sides 1–20 years previously. For stream sections 100 m long in each buffer, all logs greater than 7.5 cm diameter that spanned at least part of stream channel were measured. A total of 658 logs were recorded. Windthrown trees were comparable in characteristics to the trees that made up the buffer. The majority of logs derived from Windthrown trees were oriented perpendicular to the stream channel and were suspended above the stream channel. Even 20 years after harvesting, two-thirds of the logs were still suspended above the stream. Logs in older buffers were more decayed, and the decay rate depended on tree species and initial diameter. Log height above stream was negatively correlated with log decay class and time since logging. Log length declined with time since harvest exposure and decay class. Sediment was exposed on upturned roots and within mineral soil pits. The volume of soil retained on upturned rootwads declined over time, but some soil remained even after 20 years. Very little of this exposed sediment was close enough to the creek to result in sediment delivery.
Sylvie Gauthier - One of the best experts on this subject based on the ideXlab platform.
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Potential impact of climate change on the risk of Windthrow in eastern Canada’s forests
Climatic Change, 2017Co-Authors: Christian Saad, Jean Claude Ruel, Yan Boulanger, Marilou Beaudet, Philippe Gachon, Sylvie GauthierAbstract:Abstract Climate change is likely to affect Windthrow risks at northern latitudes by potentially changing high wind probabilities and soil frost duration. Here, we evaluated the effect of climate change on Windthrow risk in eastern Canada’s balsam fir (Abies balsamea [L.] Mill.) forests using a methodology that accounted for changes in both wind speed and soil frost duration. We used wind speed and soil temperature projections at the regional scale from the CRCM5 regional climate model (RCM) driven by the CanESM2 global climate model (GCM) under two representative concentration pathways (RCP4.5, RCP8.5), for a baseline (1976–2005) and two future periods (2041–2070, 2071–2100). A hybrid mechanistic model (ForestGALES) that considers species resistance to uprooting and wind speed distribution was used to calculate Windthrow risk. An increased risk of Windthrow (3 to 30%) was predicted for the future mainly due to an increased duration of unfrozen soil conditions (by up to 2 to 3 months by the end of the twenty-first century under RCP8.5). In contrast, wind speed did not vary markedly with a changing climate. Strong regional variations in wind speeds translated into regional differences in Windthrow risk, with the easternmost region (Atlantic provinces) having the strongest winds and the highest Windthrow risk. Because of the inherent uncertainties associated with climate change projections, especially regarding wind climate, further research is required to assess Windthrow risk from the optimum combination of RCM/GCM ensemble simulations.
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potential impact of climate change on the risk of Windthrow in eastern canada s forests
Climatic Change, 2017Co-Authors: Christian Saad, Jean Claude Ruel, Yan Boulanger, Marilou Beaudet, Philippe Gachon, Sylvie GauthierAbstract:Abstract Climate change is likely to affect Windthrow risks at northern latitudes by potentially changing high wind probabilities and soil frost duration. Here, we evaluated the effect of climate change on Windthrow risk in eastern Canada’s balsam fir (Abies balsamea [L.] Mill.) forests using a methodology that accounted for changes in both wind speed and soil frost duration. We used wind speed and soil temperature projections at the regional scale from the CRCM5 regional climate model (RCM) driven by the CanESM2 global climate model (GCM) under two representative concentration pathways (RCP4.5, RCP8.5), for a baseline (1976–2005) and two future periods (2041–2070, 2071–2100). A hybrid mechanistic model (ForestGALES) that considers species resistance to uprooting and wind speed distribution was used to calculate Windthrow risk. An increased risk of Windthrow (3 to 30%) was predicted for the future mainly due to an increased duration of unfrozen soil conditions (by up to 2 to 3 months by the end of the twenty-first century under RCP8.5). In contrast, wind speed did not vary markedly with a changing climate. Strong regional variations in wind speeds translated into regional differences in Windthrow risk, with the easternmost region (Atlantic provinces) having the strongest winds and the highest Windthrow risk. Because of the inherent uncertainties associated with climate change projections, especially regarding wind climate, further research is required to assess Windthrow risk from the optimum combination of RCM/GCM ensemble simulations.
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Effects of post-Windthrow salvage logging on microsites, plant composition and regeneration
Applied Vegetation Science, 2013Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie Gauthier, Louis De Grandpré, Chris J. PetersonAbstract:AbstractQuestions: How does Windthrow influence plant diversity and composition aswell as regeneration and microsite characteristics? What are the consequencesofpost-Windthrowsalvageloggingonthesekeyattributes?Location:Easternblackspruce–mossforest,Quebec,Canada.Methods:Atotalof92plotsweresampled,eachwitharadiusof11.28 m;49ofthese plots were salvaged while 43 were unsalvaged. Regeneration density,plantdiversityandseedbedswerecharacterized.Wetestedtheeffectofmicroto-pography and Windthrow severity on species richness and Shannon diversityindex for salvaged and unsalvaged Windthrows using a mixed model. Partialredundancyanalysis(RDA)determinedwhichenvironmentalandstandcharac-teristicsweremostimportantinexplainingdifferencesinplantspeciesandforestfloortypesamongthetreatments.Theeffectsof treatments(salvaged and unsal-vagedWindthrows),microtopographyattributes,Windthrowseverityandregen-eration species on seedling and sapling abundance were tested using a linearmixedmodel.Results:SalvagedWindthrow,withalargeproportionofskidtrails,deadmossesand Sphagnum, had a lower degree of seedbed heterogeneity. Also, some under-storey species present in the unsalvaged ecosystem were absent from the sal-vaged Windthrow. Sphagnum and other moss species were clearly associatedwith the unsalvaged treatment. White birches were positively associated withmoundmicrotopographyintheunsalvagedWindthrow.Conclusion: From an ecosystem-based forest management perspective, naturalpost-Windthrow understorey conditions and microsite heterogeneity can be inpart maintained in salvaged cut blocks by incorporating retention patches thatinclude downed and standing dead wood and living trees of diverse sizes. Thesestepsshouldfavourplantregenerationandaugmentdiversityforsalvageloggingafterwinddisturbance.IntroductionIn many parts of the world, major disturbance episodesoften lead to salvage logging (often called sanitary loggingin Europe; Lindenmayer et al. 2004, 2008). Functionally,salvage logging can be distinguished from other harvestoperations in that, with salvaging after natural distur-bance, the ecosystem is subjected to two sequential distur-bances within a short period (Lindenmayer et al. 2008).Peterson & Leach (2008) suggest that multiple disturbanceimpacts need to be understood on the basis of cumulativeseverity. Indeed, recent conceptual advances (e.g. the cuspmodel of Frelich & Reich 1999; the three-axis model ofRoberts 2004, 2007) have begun to address the potentialfor multiple disturbances to change the trajectory of com-munity development, sometimes in undesirable directions(Paine et al. 1998). Because of the potential for thecombined severity of natural disturbance followed bysalvaging to yield unwanted ‘ecological surprises’ (Paineet al. 1998), guidelines are needed for the planning of
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Forest structural attributes after Windthrow and consequences of salvage logging
Forest Ecology and Management, 2013Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie GauthierAbstract:Abstract In the eastern boreal forest of Quebec (Canada) Windthrow is a major natural disturbance, given the long fire cycle interval. Understanding Windthrow is essential to ecosystem-based forest management. Dead wood, live trees, and pit-and-mound microtopography are major post-Windthrow attributes with known ecological importance. So far, these structural post-Windthrow attributes have not been described for this ecosystem. In addition, ecological consequences of salvage logging after Windthrow remain unknown, with no specific salvage standard being applied to maintain such attributes and biological legacies. In this study, comparisons were made between salvaged and unsalvaged Windthrow to identify which post-Windthrow attributes were more greatly affected by harvest operations and to clarify management options. Downed coarse woody debris (downed CWD), snags, live trees, and pits and mounds were characterized. We showed that downed CWD and snags diminished after salvage operations, with a more uniform distribution among decay classes. Pit and mound density was reduced after salvage logging compared to unsalvaged Windthrow, with pits being smaller in the salvaged plots. From an ecosystem management perspective, retention patches with dead wood and standing living trees should be kept in salvaged cut-blocks. To minimize salvage operation effects on microtopography, machinery trails should be reduced to a minimum. Also, a certain proportion of Windthrow should be exempted from logging operations.
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The effects of site characteristics on the landscape-level Windthrow regime in the North Shore region of Quebec, Canada
Forestry, 2012Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie GauthierAbstract:Understanding Windthrow is essential for the implementation of ecosystem management, especially in forests with long fire return intervals. Our study describes Windthrow dynamics at a landscape scale of the Quebec North Shore region, Canada, and evaluates the effect of some site (soil surface material thickness or deposit thickness, drainage, slope, topography and wind), and stand (dominant species, height and density) characteristics on Windthrow probabilities. The SIFORT database, created by the Ministry of Natural Resources and Wildlife of Quebec, the Quebec forest fire control agency and the Quebec forest pest and disease control agency, was used to perform a spatiotemporal analysis of Windthrow, according to site and stand characteristics. Windthrow probabilities were influenced by topographic exposure (topex), slope classes and deposit thickness. Windthrow probabilities increased with topographic exposure. Windthrow occurrence was highest when deposit was thick (more than 1m) and slope class was medium (from 15 to 30 per cent). Finally, this study has shown the importance of partial Windthrow at the landscape scale in the North Shore region. Thus our results suggest that from an ecosystem management perspective, clear-cutting must be partly replaced by partial cuts, in order to emulate the regional dynamics of partial Windthrow.
Kaysandra Waldron - One of the best experts on this subject based on the ideXlab platform.
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Effects of post-Windthrow salvage logging on microsites, plant composition and regeneration
Applied Vegetation Science, 2013Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie Gauthier, Louis De Grandpré, Chris J. PetersonAbstract:AbstractQuestions: How does Windthrow influence plant diversity and composition aswell as regeneration and microsite characteristics? What are the consequencesofpost-Windthrowsalvageloggingonthesekeyattributes?Location:Easternblackspruce–mossforest,Quebec,Canada.Methods:Atotalof92plotsweresampled,eachwitharadiusof11.28 m;49ofthese plots were salvaged while 43 were unsalvaged. Regeneration density,plantdiversityandseedbedswerecharacterized.Wetestedtheeffectofmicroto-pography and Windthrow severity on species richness and Shannon diversityindex for salvaged and unsalvaged Windthrows using a mixed model. Partialredundancyanalysis(RDA)determinedwhichenvironmentalandstandcharac-teristicsweremostimportantinexplainingdifferencesinplantspeciesandforestfloortypesamongthetreatments.Theeffectsof treatments(salvaged and unsal-vagedWindthrows),microtopographyattributes,Windthrowseverityandregen-eration species on seedling and sapling abundance were tested using a linearmixedmodel.Results:SalvagedWindthrow,withalargeproportionofskidtrails,deadmossesand Sphagnum, had a lower degree of seedbed heterogeneity. Also, some under-storey species present in the unsalvaged ecosystem were absent from the sal-vaged Windthrow. Sphagnum and other moss species were clearly associatedwith the unsalvaged treatment. White birches were positively associated withmoundmicrotopographyintheunsalvagedWindthrow.Conclusion: From an ecosystem-based forest management perspective, naturalpost-Windthrow understorey conditions and microsite heterogeneity can be inpart maintained in salvaged cut blocks by incorporating retention patches thatinclude downed and standing dead wood and living trees of diverse sizes. Thesestepsshouldfavourplantregenerationandaugmentdiversityforsalvageloggingafterwinddisturbance.IntroductionIn many parts of the world, major disturbance episodesoften lead to salvage logging (often called sanitary loggingin Europe; Lindenmayer et al. 2004, 2008). Functionally,salvage logging can be distinguished from other harvestoperations in that, with salvaging after natural distur-bance, the ecosystem is subjected to two sequential distur-bances within a short period (Lindenmayer et al. 2008).Peterson & Leach (2008) suggest that multiple disturbanceimpacts need to be understood on the basis of cumulativeseverity. Indeed, recent conceptual advances (e.g. the cuspmodel of Frelich & Reich 1999; the three-axis model ofRoberts 2004, 2007) have begun to address the potentialfor multiple disturbances to change the trajectory of com-munity development, sometimes in undesirable directions(Paine et al. 1998). Because of the potential for thecombined severity of natural disturbance followed bysalvaging to yield unwanted ‘ecological surprises’ (Paineet al. 1998), guidelines are needed for the planning of
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Forest structural attributes after Windthrow and consequences of salvage logging
Forest Ecology and Management, 2013Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie GauthierAbstract:Abstract In the eastern boreal forest of Quebec (Canada) Windthrow is a major natural disturbance, given the long fire cycle interval. Understanding Windthrow is essential to ecosystem-based forest management. Dead wood, live trees, and pit-and-mound microtopography are major post-Windthrow attributes with known ecological importance. So far, these structural post-Windthrow attributes have not been described for this ecosystem. In addition, ecological consequences of salvage logging after Windthrow remain unknown, with no specific salvage standard being applied to maintain such attributes and biological legacies. In this study, comparisons were made between salvaged and unsalvaged Windthrow to identify which post-Windthrow attributes were more greatly affected by harvest operations and to clarify management options. Downed coarse woody debris (downed CWD), snags, live trees, and pits and mounds were characterized. We showed that downed CWD and snags diminished after salvage operations, with a more uniform distribution among decay classes. Pit and mound density was reduced after salvage logging compared to unsalvaged Windthrow, with pits being smaller in the salvaged plots. From an ecosystem management perspective, retention patches with dead wood and standing living trees should be kept in salvaged cut-blocks. To minimize salvage operation effects on microtopography, machinery trails should be reduced to a minimum. Also, a certain proportion of Windthrow should be exempted from logging operations.
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The effects of site characteristics on the landscape-level Windthrow regime in the North Shore region of Quebec, Canada
Forestry, 2012Co-Authors: Kaysandra Waldron, Jean Claude Ruel, Sylvie GauthierAbstract:Understanding Windthrow is essential for the implementation of ecosystem management, especially in forests with long fire return intervals. Our study describes Windthrow dynamics at a landscape scale of the Quebec North Shore region, Canada, and evaluates the effect of some site (soil surface material thickness or deposit thickness, drainage, slope, topography and wind), and stand (dominant species, height and density) characteristics on Windthrow probabilities. The SIFORT database, created by the Ministry of Natural Resources and Wildlife of Quebec, the Quebec forest fire control agency and the Quebec forest pest and disease control agency, was used to perform a spatiotemporal analysis of Windthrow, according to site and stand characteristics. Windthrow probabilities were influenced by topographic exposure (topex), slope classes and deposit thickness. Windthrow probabilities increased with topographic exposure. Windthrow occurrence was highest when deposit was thick (more than 1m) and slope class was medium (from 15 to 30 per cent). Finally, this study has shown the importance of partial Windthrow at the landscape scale in the North Shore region. Thus our results suggest that from an ecosystem management perspective, clear-cutting must be partly replaced by partial cuts, in order to emulate the regional dynamics of partial Windthrow.
K. Katzensteiner - One of the best experts on this subject based on the ideXlab platform.
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Soil CO 2 efflux from mountainous Windthrow areas: dynamics over 12 years post-disturbance
Biogeosciences, 2014Co-Authors: Mathias Mayer, B. Matthews, A. Schindlbacher, K. KatzensteinerAbstract:Windthrow-driven changes in carbon (C) alloca- tion and soil microclimate can affect soil carbon dioxide (CO2) efflux (Fsoil) from forest ecosystems. Although Fsoil is the dominant C flux following stand-replacing disturbance, the effects of catastrophic Windthrow on Fsoil are still poorly understood. We measured Fsoil at a montane mixed-forest site and at a subalpine spruce forest site from 2009 un- til 2012. Each site consisted of an undisturbed forest stand and two adjacent partially cleared (stem-fraction-harvested) Windthrow areas, which differed with regard to the time since disturbance. The combination of chronosequence and direct time-series approaches enabled us to investigate Fsoil dynam- ics over 12 years post-disturbance. At both sites Fsoil rates did not differ significantly from those of the undisturbed stands in the initial phase after disturbance (1-6 years). In the later phase after disturbance (9-12 years), Fsoil rates were significantly higher than in the corresponding undis- turbed stand. Soil temperature increased significantly follow- ing Windthrow (by 2.9-4.8 C), especially in the initial phase post-disturbance when vegetation cover was sparse. A sig- nificant part (15-31 %) of Fsoil from the Windthrow areas was attributed to the increase in soil temperature. Accord- ing to our estimates, 500-700 g C m 2 year 1 are released via Fsoil from south-facing forest sites in the Austrian Cal- careous Alps in the initial 6 years after Windthrow. With a high browsing pressure suppressing tree regeneration, post- disturbance net loss of ecosystem C to the atmosphere is likely to be substantial unless forest management is proac- tive in regenerating such sites. An increase in the frequency of forest disturbance by Windthrow could therefore decrease soil C stocks and feed back positively on rising atmospheric CO2 concentrations.
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Soil CO<sub>2</sub> efflux from mountainous Windthrow areas: dynamics over 12 years post-disturbance
Biogeosciences Discussions, 2014Co-Authors: M. Mayer, B. Matthews, A. Schindlbacher, K. KatzensteinerAbstract:Abstract. Windthrow driven changes in carbon (C) allocation and soil microclimate can affect soil carbon dioxide (CO2) efflux (Fsoil) of forest ecosystems. Although Fsoil is the dominant C flux following stand-replacing disturbance, the effects of catastrophic Windthrow on Fsoil are still poorly understood. We measured Fsoil at a montane mixed forest site and at a subalpine spruce forest site from 2009 until 2012. Both sites consisted of undisturbed forest stands and two adjacent Windthrow areas which differed in time since disturbance. The combination of chronosequence and direct time-series approaches enabled us to investigate Fsoil dynamics over 12 years post-disturbance. In the initial phase after disturbance (1–6 years), Fsoil rates did not differ significantly from those of the undisturbed stands, but in the later phase (9–12 years after disturbance) Fsoil rates were significantly higher than corresponding undisturbed stand values. The higher Fsoil rates in the later phase post-disturbance are likely explained by a dense vegetation cover and correspondingly higher autotrophic respiration rates. Soil temperature increased significantly following Windthrow (by 2.9–4.8 °C) especially in the initial phase post-disturbance when vegetation cover was sparse. A significant part (20–36%) of Fsoil from the Windthrow areas was thus attributed to disturbance induced changes in soil temperature. According to our estimates, ~500 to 700 g C m−2yr−1 are released via Fsoil from south-facing forest sites in the Austrian Calcareous Alps in the initial 6 years after Windthrow. With high game pressure suppressing primary production in these areas, post-disturbance loss of ecosystem C to the atmosphere is likely to be substantial unless management is proactive in regenerating such sites. An increase in the frequency of forest disturbance by Windthrow could therefore decrease soil C stocks and positively feedback on rising atmospheric CO2 concentrations.
