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Thomas H Deluca - One of the best experts on this subject based on the ideXlab platform.
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the influence of Fire history on soil nutrients and vegetation cover in mixed severity Fire Regime forests of the eastern olympic peninsula washington usa
Forest Ecology and Management, 2018Co-Authors: Melissa R A Pingree, Thomas H DelucaAbstract:Abstract The rain shadow forests of the Olympic Peninsula exemplify a mixed-severity Fire Regime class in the midst of a highly productive landscape where spatial heterogeneity of Fire severity may have significant implications for below and aboveground post-Fire recovery. The purpose of this study was to quantify the impacts of wildFire on forest soil carbon (C) and nitrogen (N) pools and assess the relationship of pyrogenic carbon (PyC) to soil processes in this mixed-severity ecosystem. We established a 112-year Fire chronosequence with nine similar forest stands ranging in time since lastFire (TSF) from 3 to 115 years prior to site establishment. At each site, we measured understory vegetation cover, overstory composition, physical and chemical attributes of surface mineral soils to a depth of 10 cm, and forest floor organic matter. Additionally, non-ionic resin lysimeters were buried over the winter and spring (7–8 months) at the interface of organic and mineral soil to collect O-horizon leached DOC that would potentially contact PyC particles on the forest floor. Nitrogen transformations were also monitored in laboratory soil incubations for a subset of sites. The TSF gradient was significantly correlated with PyC mass in the O-horizon (r = −0.4), O-horizon C (r = 0.4), total phenol content in both O-horizon (r = 0.4) and mineral soils (r = 0.2), and potentially mineralizable N (PMN) (r = 0.4). Recent Fire sites contained higher mineral soil total N and inorganic available N, but were not correlated with TSF. Total DOC that accumulated on the non-ionic resins averaged 1.14 (SE ± 0.54) g DOC m−2 year−1 and increased with TSF (r = 0.52; p
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the influence of Fire history on soil nutrients and vegetation cover in mixed severity Fire Regime forests of the eastern olympic peninsula washington usa
Forest Ecology and Management, 2018Co-Authors: Melissa R A Pingree, Thomas H DelucaAbstract:Abstract The rain shadow forests of the Olympic Peninsula exemplify a mixed-severity Fire Regime class in the midst of a highly productive landscape where spatial heterogeneity of Fire severity may have significant implications for below and aboveground post-Fire recovery. The purpose of this study was to quantify the impacts of wildFire on forest soil carbon (C) and nitrogen (N) pools and assess the relationship of pyrogenic carbon (PyC) to soil processes in this mixed-severity ecosystem. We established a 112-year Fire chronosequence with nine similar forest stands ranging in time since lastFire (TSF) from 3 to 115 years prior to site establishment. At each site, we measured understory vegetation cover, overstory composition, physical and chemical attributes of surface mineral soils to a depth of 10 cm, and forest floor organic matter. Additionally, non-ionic resin lysimeters were buried over the winter and spring (7–8 months) at the interface of organic and mineral soil to collect O-horizon leached DOC that would potentially contact PyC particles on the forest floor. Nitrogen transformations were also monitored in laboratory soil incubations for a subset of sites. The TSF gradient was significantly correlated with PyC mass in the O-horizon (r = −0.4), O-horizon C (r = 0.4), total phenol content in both O-horizon (r = 0.4) and mineral soils (r = 0.2), and potentially mineralizable N (PMN) (r = 0.4). Recent Fire sites contained higher mineral soil total N and inorganic available N, but were not correlated with TSF. Total DOC that accumulated on the non-ionic resins averaged 1.14 (SE ± 0.54) g DOC m−2 year−1 and increased with TSF (r = 0.52; p
Jon E Keeley - One of the best experts on this subject based on the ideXlab platform.
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mapping Fire Regime ecoregions in california
International Journal of Wildland Fire, 2020Co-Authors: Alexandra D Syphard, Jon E KeeleyAbstract:The Fire Regime is a central framing concept in wildFire science and ecology and describes how a range of wildFire characteristics vary geographically over time. Understanding and mapping Fire Regimes is important for guiding appropriate management and risk reduction strategies and for informing research on drivers of global change and altered Fire patterns. Most efforts to spatially delineate Fire Regimes have been conducted by identifying natural groupings of Fire parameters based on available historical Fire data. This can result in classes with similar Fire characteristics but wide differences in ecosystem types. We took a different approach and defined Fire Regime ecoregions for California to better align with ecosystem types, without using Fire as part of the definition. We used an unsupervised classification algorithm to segregate the state into spatial clusters based on distinctive biophysical and anthropogenic attributes that drive Fire Regimes – and then used historical Fire data to evaluate the ecoregions. The Fire Regime ecoregion map corresponded well with the major land cover types of the state and provided clear separation of historical patterns in Fire frequency and size, with lower variability in Fire severity. This methodology could be used for mapping Fire Regimes in other regions with limited historical Fire data or forecasting future Fire Regimes based on expected changes in biophysical characteristics.
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abrupt climate independent Fire Regime changes
Ecosystems, 2014Co-Authors: Juli G Pausas, Jon E KeeleyAbstract:WildFires have played a determining role in distribution, composition and structure of many ecosystems worldwide and climatic changes are widely considered to be a major driver of future Fire Regime changes. However, forecasting future climatic change induced impacts on Fire Regimes will require a clearer understanding of other drivers of abrupt Fire Regime changes. Here, we focus on evidence from different environmental and temporal settings of Fire Regimes changes that are not directly attributed to climatic changes. We review key cases of these abrupt Fire Regime changes at different spatial and temporal scales, including those directly driven (i) by fauna, (ii) by invasive plant species, and (iii) by socio-economic and policy changes. All these drivers might generate non-linear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity, and thus drastically change Fire activity. Although climatic changes might contribute to some of these changes, there are also many instances that are not primarily linked to climatic shifts. Understanding the mechanism driving Fire Regime changes should contribute to our ability to better assess future Fire Regimes.
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historic Fire Regime in southern california shrublands
Conservation Biology, 2001Co-Authors: Jon E Keeley, C J FotheringhamAbstract:Historical variability in Fire Regime is a conservative indicator of ecosystem sustainability, and thus understanding the natural role of Fire in chaparral ecosystems is necessary for proper Fire management. It has been suggested that the "natural" Fire Regime was one of frequent small Fires that fragmented the land- scape into a fine-grained mixture of age classes that precluded large, catastrophic Fires. Some researchers claim that this Regime was lost because of highly effective Fire suppression and conclude that if Fire managers could "restore" a Regime of frequent Fires with widespread prescription burning, they could eliminate the haz- ard of catastrophic Fires. The primary evidence in support of this model is a study that compared contempo- rary burning patterns in southern California, U.S.A., a region subject to Fire suppression, with patterns in northern Baja California, Mexico, where there is less effective Fire suppression. We found that differences in Fire Regime between these two regions are inconclusive and could not be ascribed conclusively to differences in Fire suppression. Historical records suggest that the natural Fire Regime in southern California shrublands was rather coarse-grained and not substantively different from the contemporary Regime. There is no evi- dence that Fire-management policies have created the contemporary Fire Regime dominated by massive Santa Ana wind-driven Fires. Increased expenditures on Fire suppression and increased loss of property and lives are the result of human demographic patterns that place increasing demand on Fire-suppression forces.
Lori D. Daniels - One of the best experts on this subject based on the ideXlab platform.
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a disrupted historical Fire Regime in central british columbia
Frontiers in Ecology and Evolution, 2021Co-Authors: Wesley Brookes, Lori D. Daniels, Jennifer N. Baron, Kelsey Copesgerbitz, Allan L. CarrollAbstract:In the 2017 and 2018, 2.5 million hectares burned across British Columbia, Canada, including unanticipated large and high-severity Fires in many dry forests. To transform forest and Fire management to achieve resilience to future megaFires requires improved understanding historical Fire frequency, severity and spatial patterns. Our dendroecological reconstructions of 35 plots in a 98-hectare study area in a dry Douglas-fir forest revealed historical Fires that burned at a wide range of frequencies and severities at both the plot- and study-area scales. The 23 Fires between 1619 and 1943 burned at intervals of 10‒30 years, primarily at low- to moderate-severity that scarred trees but generated few cohorts. In contrast, current Fire-free intervals of 70‒180 years exceed historical maximum intervals. Of the six widespread Fires from 1790‒1905, the 1863 Fire affected 86% of plots and was moderate in severity with patches of higher severity that generated cohorts at fine scales only. These results indicate the severity of Fires varied at fine spatial scales, and offer little support for the common assertion that periodic, high-severity, stand-initiating events were a component of the mixed-severity Fire Regime in these forest types. Many studies consider Fires in the late 1800s relatively severe because they generated new cohorts of trees, and thus, emphasize the importance of high-severity Fires in a mixed-severity Fire Regime. In our study area, the most widespread and severe Fire was not a stand-initiating Fire. Rather, the post-1863 cohorts persisted due disruption of the Fire Regime in the 20th century when land-use shifted from Indigenous Fire stewardship and early European settler Fires to Fire exclusion and suppression. In absence of low-to-moderate severity Fires, contemporary forests are dense with closed canopies that are vulnerable to high-severity Fire. Future management should reduce forest densities and to restore stand- and landscape-level heterogeneity and increase forest resilience. The timing and size of repeat treatments such as thinning of subcanopy trees and prescribed burning, including Indigenous Fire stewardship, can be guided by our refined understanding of the mixed-severity Fire Regime that was historically dominated by low-to-moderate-severity Fires in this dry forest ecosystem.
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A Disrupted Historical Fire Regime in Central British Columbia
'Frontiers Media SA', 2021Co-Authors: Wesley Brookes, Lori D. Daniels, Kelsey Copes-gerbitz, Jennifer N. Baron, Allan L. CarrollAbstract:In the 2017 and 2018, 2.55 million hectares burned across British Columbia, Canada, including unanticipated large and high-severity Fires in many dry forests. To transform forest and Fire management to achieve resilience to future megaFires requires improved understanding historical Fire frequency, severity, and spatial patterns. Our dendroecological reconstructions of 35 plots in a 161-hectare study area in a dry Douglas-fir forest revealed historical Fires that burned at a wide range of frequencies and severities at both the plot- and study-area scales. The 23 Fires between 1619 and 1943 burned at intervals of 10–30 years, primarily at low- to moderate-severity that scarred trees but generated few cohorts. In contrast, current Fire-free intervals of 70–180 years exceed historical maximum intervals. Of the six widespread Fires from 1790 to 1905, the 1863 Fire affected 86% of plots and was moderate in severity with patches of higher severity that generated cohorts at fine scales only. These results indicate the severity of Fires varied at fine spatial scales, and offer little support for the common assertion that periodic, high-severity, stand-initiating events were a component of the mixed-severity Fire Regime in these forest types. Many studies consider Fires in the late 1800s relatively severe because they generated new cohorts of trees, and thus, emphasize the importance of high-severity Fires in a mixed-severity Fire Regime. In our study area, the most widespread and severe Fire was not a stand-initiating Fire. Rather, the post-1863 cohorts persisted due disruption of the Fire Regime in the twentieth century when land-use shifted from Indigenous Fire stewardship and early European settler Fires to Fire exclusion and suppression. In absence of low- to moderate-severity Fires, contemporary forests are dense with closed canopies that are vulnerable to high-severity Fire. Future management should reduce forest densities and to restore stand- and landscape-level heterogeneity and increase forest resilience. The timing and size of repeat treatments such as thinning of subcanopy trees and prescribed burning, including Indigenous Fire stewardship, can be guided by our refined understanding of the mixed-severity Fire Regime that was historically dominated by low- to moderate-severity Fires in this dry forest ecosystem
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monthly adaptations of the drought code reveal nuanced Fire drought associations in montane forests with a mixed severity Fire Regime
International Journal of Wildland Fire, 2019Co-Authors: Raphaël D. Chavardès, Lori D. Daniels, Bianca N.i. Eskelson, Paul D. PickellAbstract:We compared three monthly adaptations of the daily Drought Code (DC) of Canada’s Fire Weather Index System and applied them to interpret drought conditions associated with historical Fires in montane forests of south-eastern British Columbia. The three adaptations were compared with the monthly mean DC calculated from daily values for the Palliser Fire-weather station. Two adaptations improved on the existing Monthly DC calculated from monthly climate data by (1) accounting for overwinter drying and an early start to the Fire season, and (2) improving estimates of effective precipitation. Using a cross-dated Fire-scar record from 20 sites in montane forests surrounding the Palliser station, we found significant Fire–drought associations from June to August with all adaptations, and significant associations in April and May with the two new adaptations. Of the 17 Fire years from 1901 to 2013, 6 years had low initial drought conditions that increased late in the Fire season, and 5 years had high drought conditions throughout the Fire season. We conclude that variable drought within and among Fire seasons influenced Fire severity. Our findings provide a connection between modern drought indices used to rank Fire danger and drought effects on the historical mixed-severity Fire Regime in montane forests of south-eastern British Columbia.
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Human influences superseded climate to disrupt the 20th century Fire Regime in Jasper National Park, Canada
Dendrochronologia, 2018Co-Authors: Raphaël D. Chavardès, Lori D. Daniels, Ze’ev Gedalof, David W. AndisonAbstract:Abstract To enhance understanding of how climate and humans influenced historical Fire occurrence in the montane forests of Jasper National Park, we crossdated Fire-scar and tree age samples from 172 plots. We tested effects of drought and climatic variation driven by the El Nino-Southern Oscillation (ENSO) and Pacific North American (PNA) pattern on Fire occurrence. We also tested whether local droughts were associated with ENSO, PNA, Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation. We used a combination of instrumental and proxy-climate records to test whether climatic variation explained the absence of Fire scars in our study area during the 20th century. From 1646 to 1915, 18 Fires burned mainly during drier than average years. Drought years, but not Fire years, were associated with positive ENSO and PNA indices, corresponding to warmer conditions with reduced snowpacks. Fire frequency varied through time, although no Fire scars have formed since 1915. Potential recording trees present at all plots and climate conducive to Fire over multiple years provide evidence that human influences superseded climatic variation to explain the lack of Fire scars during the 20th century. Fire suppression significantly altered the Fire Regime after the formation of Jasper National Park, justifying the ongoing mechanical fuel treatments, prescribed and managed wildFires to improve forest resilience to climate change.
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altered mixed severity Fire Regime has homogenised montane forests of jasper national park
International Journal of Wildland Fire, 2016Co-Authors: Raphaël D. Chavardès, Lori D. DanielsAbstract:Fire suppression has altered the historical mixed-severity Fire Regime and homogenised forest structures in Jasper National Park, Canada. We used dendrochronology to reconstruct Fire history and assess forest dynamics at 29 sites in the montane forests. Based on Fire scars and even-aged post-Fire cohorts, we determined 18 sites had mixed-severity Fire histories through time, and 11 sites had evidence of high-severity Fires only – yielding a mixed-severity Fire Regime for the study area. Lodgepole pine, hybrid spruce and Douglas-fir established simultaneously after low- and high-severity Fires. Regardless of Fire history, forest canopies were mixed in composition and subcanopies were strongly dominated by shade-tolerant hybrid spruce. Despite their size, subcanopy trees were similar in age to the canopy trees. Current stand composition and age structures largely reflect the effects of high-severity Fires that burned ~110 years ago at 18 of 29 sites. In the absence of Fires after 1905, forests have matured simultaneously, homogenising the landscape and resulting in forest structures that are more conducive to high-severity Fire than are Fires of a range of severities. Proactive Fire management is justified to restore Fire as a vital ecological process and promote forest resilience by countering the effects of a century of Fire suppression.
Juli G Pausas - One of the best experts on this subject based on the ideXlab platform.
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Socioeconomic Factors Drive Fire-Regime Variability in the Mediterranean Basin
Ecosystems, 2018Co-Authors: Brahim Chergui, Soumia Fahd, Xavier Santos, Juli G PausasAbstract:In recent decades, Fires in Mediterranean Europe have become larger and more frequent. This trend has been driven by socioeconomic changes that have generated rural depopulation and changes in traditional land use. Within the Mediterranean Basin, the most contrasting socioeconomic conditions are found by comparing southern European with North African countries, and thus our hypothesis is that this difference generates contrasting Fire Regimes between the two regions. Specifically, we predict that current Fire Regimes in Mediterranean Africa resemble past Fire Regimes in the Mediterranean Europe when rural activities dominated the landscape. To test our hypothesis, we compared Fire statistics from the western Rif (northern Morocco, 1988–2015) and from Valencia (eastern Spain, 1880–2014). The results suggest that the Rif has a typical Mediterranean Fire Regime with Fires occurring in the hot, dry summer season. However, Fires are very small and the annual proportion of burnt area is very low, compared to the current Regime in Valencia (post-1970s). The current Rif Fire size class distribution matches the Fire Regime in Valencia prior to the 1970s before the collapse of the rural population and when Fires were fuel-limited. The shift in the recent decades in Fire Regime observed in different countries of the Mediterranean Europe (from small, fuel-limited Fires to drought-driven Fires) can be identified when moving from the southern to the northern rim of the basin. That is, most spatial and temporal variability in Fire Regimes of the Mediterranean Basin is driven by shifts in the amounts of fuel and continuity imposed by changes in socioeconomic drivers.
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bark thickness and Fire Regime
Functional Ecology, 2015Co-Authors: Juli G PausasAbstract:Summary 1. Bark is a vital and very visible part of woody plants, yet only recently has bark characteristics started to be considered as key traits structuring communities and biomes. Bark thickness is very variable among woody plants, and I hypothesize that Fire is a key factor selecting for a thick bark, and thus, at the global scale, a significant proportion of the variability in bark thickness is explained by the variability in Fire Regimes. Previous research has focused on the importance of bark thickness mainly in surface-Fire Regimes; here I generalize this idea and present a conceptual framework to explain how the different drivers that affect Fire intensity have shaped bark thickness, in conjunction with other plant traits. 2. I first review methods used to study bark thickness and then provide examples of bark thickness patterns from a wide range of ecosystems subject to different Fire Regimes (understorey Fires, grass-fuelled surface Fires, grass-fuelled crown Fires and infrequent Fires). 3. There are some Fire Regimes that select for thick barks, while some only in the base of the trunk (e.g. understorey Fires), others select for a thick bark on the whole plant (e.g. grassfuelled crown Fires). There are also Fire Regimes in which allocating resources to a thick bark is not adaptive (e.g. woody-fulled crown Fires). 4. Fire Regime can explain a large proportion of the variability of bark thickness at the global scale, and thus, this trait varies across ecosystems in a predictable manner; however, the current paucity of data limits a fully accurate analysis.
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abrupt climate independent Fire Regime changes
Ecosystems, 2014Co-Authors: Juli G Pausas, Jon E KeeleyAbstract:WildFires have played a determining role in distribution, composition and structure of many ecosystems worldwide and climatic changes are widely considered to be a major driver of future Fire Regime changes. However, forecasting future climatic change induced impacts on Fire Regimes will require a clearer understanding of other drivers of abrupt Fire Regime changes. Here, we focus on evidence from different environmental and temporal settings of Fire Regimes changes that are not directly attributed to climatic changes. We review key cases of these abrupt Fire Regime changes at different spatial and temporal scales, including those directly driven (i) by fauna, (ii) by invasive plant species, and (iii) by socio-economic and policy changes. All these drivers might generate non-linear effects of landscape changes in fuel structure; that is, they generate fuel changes that can cross thresholds of landscape continuity, and thus drastically change Fire activity. Although climatic changes might contribute to some of these changes, there are also many instances that are not primarily linked to climatic shifts. Understanding the mechanism driving Fire Regime changes should contribute to our ability to better assess future Fire Regimes.
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Fire Regime changes in the western mediterranean basin from fuel limited to drought driven Fire Regime
Climatic Change, 2012Co-Authors: Juli G Pausas, Santiago FernandezmunozAbstract:WildFires are an integral part of Mediterranean ecosystems; humans impact on landscapes imply changes in fuel amount and continuity, and thus in Fire Regime. We tested the hypothesis that Fire Regime changed in western Mediterranean Basin during the last century using time series techniques. We first compiled a 130-year Fire history for the Valencia province (Spain, Eastern Iberian Peninsula, Western Mediterranean Basin) from contemporary statistics plus old forest administration dossiers and newspapers. We also compiled census on rural population and climatic data for the same period in order to evaluate the role of climate and human-driven fuel changes on the Fire Regime change. The result suggested that there was a major Fire Regime shift around the early 1970s in such a way that Fires increased in annual frequency (doubled) and area burned (by about an order of magnitude). The main driver of this shift was the increase in fuel amount and continuity due to rural depopulation (vegetation and fuel build-up after farm abandonment) suggesting that Fires were fuel-limited during the pre-1970s period. Climatic conditions were poorly related to pre-1970s Fires and strongly related to post-1970s Fires, suggesting that Fire are currently less fuel limited and more drought-driven than before the 1970s. Thus, the Fire Regime shift implies also a shift in the main driver for Fire activity, and this has consequences in the global change agenda.
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Response of plant functional types to changes in the Fire Regime in Mediterranean ecosystems: A simulation approach
Journal of Vegetation Science, 1999Co-Authors: Juli G PausasAbstract:. In the Mediterranean basin, the climate is predicted to be warmer and effectively drier, leading to changes in fuel conditions and Fire Regime. Land abandonment in the Mediterranean basin is also changing the Fire Regime through the increase in fuel loads. In the present study, two simulation models of vegetation dynamics were tested in order to predict changes in plant functional types due to changes in Fire recurrence in eastern Spain. The two modelling approaches are the FATE-model (based on vital attributes) and the gap model BROLLA (based on the gap-phase theory). The models were arranged to simulate four functional types, based mainly on their regenerative strategies after disturbance: Quercus (resprouter), Pinus (non-resprouter with serotinous cones), Erica (resprouter), and Cistus (non-resprouter with germination stimulated by Fire). The simulation results suggested a decrease in Quercus abundance, an increase in Cistus and Erica, and a maximum of Pinus at intermediate recurrence scenarios. Despite their different approaches, both models predicted a similar response to increased Fire recurrence, and the results were consistent with field observations.
Raphaël D. Chavardès - One of the best experts on this subject based on the ideXlab platform.
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monthly adaptations of the drought code reveal nuanced Fire drought associations in montane forests with a mixed severity Fire Regime
International Journal of Wildland Fire, 2019Co-Authors: Raphaël D. Chavardès, Lori D. Daniels, Bianca N.i. Eskelson, Paul D. PickellAbstract:We compared three monthly adaptations of the daily Drought Code (DC) of Canada’s Fire Weather Index System and applied them to interpret drought conditions associated with historical Fires in montane forests of south-eastern British Columbia. The three adaptations were compared with the monthly mean DC calculated from daily values for the Palliser Fire-weather station. Two adaptations improved on the existing Monthly DC calculated from monthly climate data by (1) accounting for overwinter drying and an early start to the Fire season, and (2) improving estimates of effective precipitation. Using a cross-dated Fire-scar record from 20 sites in montane forests surrounding the Palliser station, we found significant Fire–drought associations from June to August with all adaptations, and significant associations in April and May with the two new adaptations. Of the 17 Fire years from 1901 to 2013, 6 years had low initial drought conditions that increased late in the Fire season, and 5 years had high drought conditions throughout the Fire season. We conclude that variable drought within and among Fire seasons influenced Fire severity. Our findings provide a connection between modern drought indices used to rank Fire danger and drought effects on the historical mixed-severity Fire Regime in montane forests of south-eastern British Columbia.
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Human influences superseded climate to disrupt the 20th century Fire Regime in Jasper National Park, Canada
Dendrochronologia, 2018Co-Authors: Raphaël D. Chavardès, Lori D. Daniels, Ze’ev Gedalof, David W. AndisonAbstract:Abstract To enhance understanding of how climate and humans influenced historical Fire occurrence in the montane forests of Jasper National Park, we crossdated Fire-scar and tree age samples from 172 plots. We tested effects of drought and climatic variation driven by the El Nino-Southern Oscillation (ENSO) and Pacific North American (PNA) pattern on Fire occurrence. We also tested whether local droughts were associated with ENSO, PNA, Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation. We used a combination of instrumental and proxy-climate records to test whether climatic variation explained the absence of Fire scars in our study area during the 20th century. From 1646 to 1915, 18 Fires burned mainly during drier than average years. Drought years, but not Fire years, were associated with positive ENSO and PNA indices, corresponding to warmer conditions with reduced snowpacks. Fire frequency varied through time, although no Fire scars have formed since 1915. Potential recording trees present at all plots and climate conducive to Fire over multiple years provide evidence that human influences superseded climatic variation to explain the lack of Fire scars during the 20th century. Fire suppression significantly altered the Fire Regime after the formation of Jasper National Park, justifying the ongoing mechanical fuel treatments, prescribed and managed wildFires to improve forest resilience to climate change.
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altered mixed severity Fire Regime has homogenised montane forests of jasper national park
International Journal of Wildland Fire, 2016Co-Authors: Raphaël D. Chavardès, Lori D. DanielsAbstract:Fire suppression has altered the historical mixed-severity Fire Regime and homogenised forest structures in Jasper National Park, Canada. We used dendrochronology to reconstruct Fire history and assess forest dynamics at 29 sites in the montane forests. Based on Fire scars and even-aged post-Fire cohorts, we determined 18 sites had mixed-severity Fire histories through time, and 11 sites had evidence of high-severity Fires only – yielding a mixed-severity Fire Regime for the study area. Lodgepole pine, hybrid spruce and Douglas-fir established simultaneously after low- and high-severity Fires. Regardless of Fire history, forest canopies were mixed in composition and subcanopies were strongly dominated by shade-tolerant hybrid spruce. Despite their size, subcanopy trees were similar in age to the canopy trees. Current stand composition and age structures largely reflect the effects of high-severity Fires that burned ~110 years ago at 18 of 29 sites. In the absence of Fires after 1905, forests have matured simultaneously, homogenising the landscape and resulting in forest structures that are more conducive to high-severity Fire than are Fires of a range of severities. Proactive Fire management is justified to restore Fire as a vital ecological process and promote forest resilience by countering the effects of a century of Fire suppression.
