ORCID Profile
0000-0002-8587-2603
Current Organisation
Portland State University
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Publisher: Copernicus GmbH
Date: 09-03-2012
Abstract: Abstract. Fire history reconstructions are typically based on tree ages and tree-ring fire scars or on charcoal in sedimentary records from lakes or bogs, but rarely on both. In this study of fire history in western Patagonia (47–48° S) in southern South America (SSA) we compared three sedimentary charcoal records collected in bogs with tree-ring fire-scar data collected at 13 nearby s le sites. We examined the temporal and spatial correspondence between the two fire proxies and also compared them to published charcoal records from distant sites in SSA, and with published proxy reconstructions of regional climate variability and large-scale climate modes. Two of our three charcoal records record fire activity for the last 4 ka yr and one for the last 11 ka yr. For the last ca. 400 yr, charcoal accumulation peaks tend to coincide with high fire activity in the tree-ring fire scar records, but the charcoal records failed to detect some of the fire activity recorded by tree rings. Potentially, this discrepancy reflects low-severity fires that burn in herbaceous and other fine fuels without depositing charcoal in the sedimentary record. Periods of high fire activity tended to be synchronous across s le areas, across proxy types, and with proxy records of regional climatic variability as well as major climate drivers. Fire activity throughout the Holocene in western Patagonia has responded to regional climate variation affecting a broad region of southern South America that is teleconnected to both tropical- and high-latitude climate drivers-El Niño-Southern Oscillation and the Southern Annular Mode. An early Holocene peak in fire activity pre-dates any known human presence in our study area, and consequently implicates lightning as the ignition source. In contrast, the increased fire activity during the 20th century, which was concomitantly recorded by charcoal from all the s led bogs and at all fire-scar s le sites, is attributed to human-set fires and is outside the range of variability characteristic of these ecosystems over many centuries and probably millennia.
Publisher: MDPI AG
Date: 22-03-2022
DOI: 10.3390/FIRE5020041
Abstract: Nearly 0.8 million hectares of land were burned in the North American Pacific Northwest (PNW) over two weeks under record-breaking fuel aridity and winds during the extraordinary 2020 fire season, representing a rare ex le of megafires in forests west of the Cascade Mountains. We quantified the relative influence of weather, vegetation, and topography on patterns of high burn severity ( % tree mortality) among five synchronous megafires in the western Cascade Mountains. Despite the conventional wisdom in climate-limited fire regimes that regional drivers (e.g., extreme aridity, and synoptic winds) overwhelm local controls on vegetation mortality patterns (e.g., vegetation structure and topography), we hypothesized that local controls remain important influences on burn severity patterns in these rugged forested landscapes. To study these influences, we developed remotely sensed fire extent and burn severity maps for two distinct weather periods, thereby isolating the effect of extreme east winds on drivers of burn severity. Our results confirm that wind was the major driver of the 2020 megafires, but also that both vegetation structure and topography significantly affect burn severity patterns even under extreme fuel aridity and winds. Early-seral forests primarily concentrated on private lands, burned more severely than their older and taller counterparts, over the entire megafire event regardless of topography. Meanwhile, mature stands burned severely only under extreme winds and especially on steeper slopes. Although climate change and land-use legacies may prime temperate rainforests to burn more frequently and at higher severities than has been historically observed, our work suggests that future high-severity megafires are only likely to occur during coinciding periods of heat, fuel aridity, and extreme winds.
Publisher: Informa UK Limited
Date: 02-04-2016
Publisher: Wiley
Date: 28-09-2023
DOI: 10.1111/JBI.14732
Publisher: American Geophysical Union (AGU)
Date: 07-2011
DOI: 10.1029/2011GL047674
Publisher: Wiley
Date: 18-02-2011
Publisher: Springer Science and Business Media LLC
Date: 19-10-2018
DOI: 10.1038/S41467-018-06788-9
Abstract: Increasing evidence indicates that forest disturbances are changing in response to global change, yet local variability in disturbance remains high. We quantified this considerable variability and analyzed whether recent disturbance episodes around the globe were consistently driven by climate, and if human influence modulates patterns of forest disturbance. We combined remote sensing data on recent (2001–2014) disturbances with in-depth local information for 50 protected landscapes and their surroundings across the temperate biome. Disturbance patterns are highly variable, and shaped by variation in disturbance agents and traits of prevailing tree species. However, high disturbance activity is consistently linked to warmer and drier than average conditions across the globe. Disturbances in protected areas are smaller and more complex in shape compared to their surroundings affected by human land use. This signal disappears in areas with high recent natural disturbance activity, underlining the potential of climate-mediated disturbance to transform forest landscapes.
Publisher: Oxford University Press (OUP)
Date: 07-2022
DOI: 10.1093/PNASNEXUS/PGAC115
Abstract: Fire is an integral component of ecosystems globally and a tool that humans have harnessed for millennia. Altered fire regimes are a fundamental cause and consequence of global change, impacting people and the biophysical systems on which they depend. As part of the newly emerging Anthropocene, marked by human-caused climate change and radical changes to ecosystems, fire danger is increasing, and fires are having increasingly devastating impacts on human health, infrastructure, and ecosystem services. Increasing fire danger is a vexing problem that requires deep transdisciplinary, trans-sector, and inclusive partnerships to address. Here, we outline barriers and opportunities in the next generation of fire science and provide guidance for investment in future research. We synthesize insights needed to better address the long-standing challenges of innovation across disciplines to (i) promote coordinated research efforts (ii) embrace different ways of knowing and knowledge generation (iii) promote exploration of fundamental science (iv) capitalize on the “firehose” of data for societal benefit and (v) integrate human and natural systems into models across multiple scales. Fire science is thus at a critical transitional moment. We need to shift from observation and modeled representations of varying components of climate, people, vegetation, and fire to more integrative and predictive approaches that support pathways toward mitigating and adapting to our increasingly flammable world, including the utilization of fire for human safety and benefit. Only through overcoming institutional silos and accessing knowledge across erse communities can we effectively undertake research that improves outcomes in our more fiery future.
Publisher: MDPI AG
Date: 08-12-2020
DOI: 10.3390/FIRE3040070
Abstract: Characterizing wildfire regimes where wildfires are uncommon is challenged by a lack of empirical information. Moreover, climate change is projected to lead to increasingly frequent wildfires and additional annual area burned in forests historically characterized by long fire return intervals. Western Oregon and Washington, USA (westside) have experienced few large wildfires (fires greater than 100 hectares) the past century and are characterized to infrequent large fires with return intervals greater than 500 years. We evaluated impacts of climate change on wildfire hazard in a major urban watershed outside Portland, OR, USA. We simulated wildfire occurrence and fire regime characteristics under contemporary conditions (1992–2015) and four mid-century (2040–2069) scenarios using Representative Concentration Pathway (RCP) 8.5. Simulated mid-century fire seasons expanded in most scenarios, in some cases by nearly two months. In all scenarios, average fire size and frequency projections increased significantly. Fire regime characteristics under the hottest and driest mid-century scenarios illustrate novel disturbance regimes which could result in permanent changes to forest structure and composition and the provision of ecosystem services. Managers and planners can use the range of modeled outputs and simulation results to inform robust strategies for climate adaptation and risk mitigation.
Publisher: Frontiers Media SA
Date: 26-01-2018
Publisher: Past Global Changes (PAGES)
Date: 08-2010
Publisher: Wiley
Date: 26-03-2018
Publisher: Wiley
Date: 07-01-2019
Publisher: SciELO Agencia Nacional de Investigacion y Desarrollo (ANID)
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 19-06-2022
Publisher: Wiley
Date: 03-03-2020
DOI: 10.1111/GCB.15031
Publisher: Springer Science and Business Media LLC
Date: 28-10-2012
DOI: 10.1038/NGEO1613
Publisher: Elsevier BV
Date: 12-2023
Publisher: Wiley
Date: 09-2020
DOI: 10.1002/ECS2.3247
Publisher: Springer Science and Business Media LLC
Date: 24-07-2015
Publisher: MDPI AG
Date: 15-05-2021
DOI: 10.3390/FIRE4020028
Abstract: The unprecedented size of the 2017 wildfires that burned nearly 600,000 hectares of central Chile highlight a need to better understand the climatic conditions under which large fires develop. Here we evaluate synoptic atmospheric conditions at the surface and free troposphere associated with anomalously high (active) versus low (inactive) months of area burned in south-central Chile (ca. 32–41° S) from the Chilean Forest Service (CONAF) record of area burned from 1984–2018. Active fire months are correlated with warm surface temperatures, dry conditions, and the presence of a circumpolar assemblage of high-pressure systems located ca. 40°–60° S. Additionally, warm surface temperatures associated with active fire months are linked to reduced strength of cool, onshore westerly winds and an increase in warm, downslope Andean Cordillera easterly winds. Episodic warm downslope winds and easterly wind anomalies superimposed on long-term warming and drying trends will continue to create conditions that promote large fires in south-central Chile. Identifying the mechanisms responsible for easterly wind anomalies and determining whether this trend is strengthening due to synoptic-scale climatic changes such as the poleward shift in Southern Hemisphere westerly winds will be critical for anticipating future large fire activity in south-central Chile.
Publisher: Elsevier BV
Date: 03-2021
Publisher: Public Library of Science (PLoS)
Date: 22-08-2018
Publisher: Past Global Changes (PAGES)
Date: 12-2016
Publisher: Wiley
Date: 25-08-2014
DOI: 10.1111/JVS.12225
Publisher: Wiley
Date: 11-2007
DOI: 10.1890/06-1860.1
Abstract: This study investigates the influence of climatic variability on subalpine forest fire occurrence in western Colorado during the AD 1600-2003 period. Interannual and multidecadal relationships between fire occurrence and the El Niño Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), and Atlantic Multidecadal Oscillation (AMO) were examined, in addition to the effects of phase interactions among these oscillations. Fires occurred during short-term periods of significant drought and extreme cool (negative) phases of ENSO and PDO and during positive departures from mean AMO index. At longer time scales, fires exhibited 20-year periods of synchrony with the cool phase of the PDO, and 80-year periods of synchrony with extreme warm (positive) phases of the AMO. Years of combined positive AMO and negative ENSO and PDO phases represent "triple whammies" that significantly increased the occurrence of drought-induced fires. Fires were synchronous with this phase combination over 0-30 year periods and distinctly asynchronous with the opposite phase combination. Overall, because fires are synchronous at supra-annual to multidecadal time scales with warm AMO events, particularly when combined with cool ENSO and PDO phases, this suggests that we may be entering a qualitatively different fire regime in the next few decades due to the recent shift in 1998 to a likely long-term warm AMO phase. Although uncertainty remains regarding the effects of CO2-induced warming at regional scales, given the multidecadal persistence of the AMO there is mounting evidence that the recent shift to the positive phase of the AMO will promote higher fire frequencies in the region.
Publisher: Wiley
Date: 09-2017
DOI: 10.1002/ECS2.1932
Publisher: Wiley
Date: 18-08-2014
DOI: 10.1111/GCB.12674
Abstract: Athrotaxis cupressoides is a slow‐growing and long‐lived conifer that occurs in the subalpine temperate forests of Tasmania, a continental island to the south of Australia. In 1960–1961, human‐ignited wildfires occurred during an extremely dry summer that killed many A. cupressoides stands on the high plateau in the center of Tasmania. That fire year, coupled with subsequent regeneration failure, caused a loss of ca. 10% of the geographic extent of this endemic Tasmanian forest type. To provide historical context for these large‐scale fire events, we (i) collected dendroecological, floristic, and structural data, (ii) documented the postfire survival and regeneration of A. cupressoides and co‐occurring understory species, and (iii) assessed postfire understory plant community composition and flammability. We found that fire frequency did not vary following the arrival of European settlers, and that A. cupressoides populations were able to persist under a regime of low‐to‐mid severity fires prior to the 1960 fires. Our data indicate that the 1960 fires were (i) of greater severity than previous fires, (ii) herbivory by native marsupials may limit seedling survival in both burned and unburned A. cupressoides stands, and (iii) the loss of A. cupressoides populations is largely irreversible given the relatively high fuel loads of postfire vegetation communities that are dominated by resprouting shrubs. We suggest that the feedback between regeneration failure and increased flammability will be further exacerbated by a warmer and drier climate causing A. cupressoides to contract to the most fire‐proof landscape settings.
Publisher: Proceedings of the National Academy of Sciences
Date: 06-03-2023
Abstract: Increasing fire severity and warmer, drier postfire conditions are making forests in the western United States (West) vulnerable to ecological transformation. Yet, the relative importance of and interactions between these drivers of forest change remain unresolved, particularly over upcoming decades. Here, we assess how the interactive impacts of changing climate and wildfire activity influenced conifer regeneration after 334 wildfires, using a dataset of postfire conifer regeneration from 10,230 field plots. Our findings highlight declining regeneration capacity across the West over the past four decades for the eight dominant conifer species studied. Postfire regeneration is sensitive to high-severity fire, which limits seed availability, and postfire climate, which influences seedling establishment. In the near-term, projected differences in recruitment probability between low- and high-severity fire scenarios were larger than projected climate change impacts for most species, suggesting that reductions in fire severity, and resultant impacts on seed availability, could partially offset expected climate-driven declines in postfire regeneration. Across 40 to 42% of the study area, we project postfire conifer regeneration to be likely following low-severity but not high-severity fire under future climate scenarios (2031 to 2050). However, increasingly warm, dry climate conditions are projected to eventually outweigh the influence of fire severity and seed availability. The percent of the study area considered unlikely to experience conifer regeneration, regardless of fire severity, increased from 5% in 1981 to 2000 to 26 to 31% by mid-century, highlighting a limited time window over which management actions that reduce fire severity may effectively support postfire conifer regeneration.
Publisher: Science Publishers
Date: 05-01-2009
Publisher: Wiley
Date: 29-01-2013
DOI: 10.1111/GEB.12038
Publisher: Springer Science and Business Media LLC
Date: 05-2011
Publisher: Wiley
Date: 29-03-2019
DOI: 10.1111/AEC.12751
Publisher: Springer International Publishing
Date: 2017
Publisher: Informa UK Limited
Date: 09-2015
DOI: 10.2980/16-3-3262
Publisher: Oxford University Press (OUP)
Date: 12-12-2014
Publisher: Past Global Changes (PAGES)
Date: 04-2022
Publisher: American Geophysical Union (AGU)
Date: 28-05-2018
DOI: 10.1029/2018GL078294
Publisher: Public Library of Science (PLoS)
Date: 29-04-2020
Publisher: Cold Spring Harbor Laboratory
Date: 15-01-2023
DOI: 10.1101/2023.01.11.522134
Abstract: Tree mortality and partial canopy dieback are increasing in many forest ecosystems from unfavorable climate conditions. Examining how tree growth and mortality are affected by climate variability can help identify proximate causes of tree mortality and canopy dieback. We investigated anomalously high mortality rates and partial canopy dieback of western redcedar ( Thuja plicata , WRC), a culturally, ecologically, and economically important species in the Pacific Northwest (USA), using tree-ring methods. We s led trees in three tree status groups—no canopy dieback, partial canopy dieback, and trees that died (0-30 years ago)—from 11 sites in coastal (maritime climate) and interior (continental climate) populations of WRC trees. In our study, WRC tree mortality was portended by on average 4-5 years of declining radial growth. Warmer and drier climate conditions in May and June that extend the annual July-September dry season reduced radial growth in 9 of 11 sites (1975-2020). Defining drought events as warm, dry May-June climate, we found that WRC trees recovered radial growth to pre-drought rates within three years when post-drought climate conditions were average or cooler and wetter than average. However, radial growth recovery from drought was slower or absent when conditions were warmer and drier during the post-drought recovery period, which appeared to lead to the widespread mortality event across coastal populations. Annually resolved tree mortality in coastal populations predominately occurred in 2017-2018 (80% of s led trees) and coincided with exceedingly hot temperatures and the longest regionally dry period for May to September (1970-2020). In interior populations, tree mortality was associated with warmer, drier conditions from August to September. Our findings forewarn that a warming climate and more frequent and severe seasonal droughts will likely increase the vulnerability of WRC to canopy dieback and mortality and possibly other drought-sensitive trees in one of the world’s largest carbon sinks.
Publisher: Proceedings of the National Academy of Sciences
Date: 21-08-2017
Abstract: Fire is a key ecological process affecting ecosystem dynamics and services, driven primarily by variations in fuel amount and condition, ignition patterns, and climate. In the Southern Hemisphere, current warming conditions are linked to the upward trend in the Southern Annular Mode (SAM) due to ozone depletion. Here we use tree ring fire scar data obtained from erse biomes ranging from subtropical dry woodlands to sub-Antarctic rainforests to assess the effect of the SAM on regional fire activity over the past several centuries. Our findings reveal a tight coupling between fire activity and the SAM at all temporal scales and in all biomes, with increased wildfire synchrony and activity during the 20th century compared with previous centuries.
Publisher: American Geophysical Union (AGU)
Date: 19-10-2016
DOI: 10.1002/2016GL070572
Publisher: Wiley
Date: 06-2020
DOI: 10.1002/FEE.2190
Publisher: Wiley
Date: 25-03-2018
DOI: 10.1111/JBI.13199
Publisher: Elsevier BV
Date: 10-2011
Publisher: Wiley
Date: 05-2013
DOI: 10.1890/ES12-00378.1
Abstract: Despite important recent advances in modeling current and future global fire activity in relation to biophysical predictors there remain important uncertainties about finer‐scale spatial heterogeneity of fire and especially about human influences which are typically assessed at coarse‐spatial resolutions. The purpose of the current study is to quantify the influence of biophysical and anthropogenic variables on the spatial distribution of wildfire activity between 1984 and 2010 over an extensive southern Patagonian‐Andean region from ca. 43° to 53° S extending from coastal rainforests to xeric woodland and steppe. We used satellite imagery to map all detectable fires ha from 1984 to 2010 in four study areas (each of 13,100 to 36,635 km 2 ) and field checked 65 of these burns for accuracy of burned vegetation class and fire perimeters. Then, we used the MaxEnt modeling technique to assess the relationships of wildfire distributions to biophysical and human environmental variables in each of the four regions. The 232 fires ha mapped in the four study areas accounted for an area of 1,314 km 2 indicating that at least 1.8% of the total area burned between 1984 and 2010. In general, areas with intermediate productivity levels (e.g., shrublands) have higher fire probability compared with areas of low and high productivity levels, such as steppe and wet forests, respectively. There is a marked contrast in the flammability of broad vegetation classes in determining fire activity at a regional scale, as well as a strong spatial relationship of wildfires to anthropogenic variables. The juxtaposition of fire‐resistant tall forests with fire‐prone shrublands and woodlands creates the potential for positive feedbacks from human‐set fires to gradually increase the flammability of extensive landscapes through repeated burning. Distance to roads and settlements were also strong predictors, suggesting that fire in all regions is ignition‐limited. However, these anthropogenic predictors influenced probability of fire differently among study regions depending on their main land‐use practices and their past and present socioeconomic contexts.
Publisher: Wiley
Date: 14-06-2022
DOI: 10.1111/GEB.13555
Abstract: Historically, wildfire regimes produced important landscape‐scale disturbances in many regions globally. The “pyro ersity begets bio ersity” hypothesis suggests that wildfires that generate temporally and spatially heterogeneous mosaics of wildfire severity and post‐burn recovery enhance bio ersity at landscape scales. However, river management has often led to channel incision that disconnects rivers from their floodplains, desiccating floodplain habitats and depleting groundwater. In conjunction with predicted increases in frequency, intensity and extent of wildfires under climate change, this increases the likelihood of deep, uniform burns that reduce bio ersity. Recent focus on floodplain re‐wetting and restoration of successional floodplain habitat mosaics, developed for river management and flood prevention, could reduce wildfire intensity in restored floodplains and make the burns less uniform, increasing climate‐change resilience an important synergy. According to theory, this would also enhance bio ersity. However, this possibility is yet to be tested empirically. We suggest potential research avenues. We illustrate the interaction between wildfire and river restoration using a restoration project in Oregon, USA. A project to reconnect the South Fork McKenzie River and its floodplain suffered a major burn (“Holiday Farm” wildfire, 2020), offering a rare opportunity to study the interaction between this type of river restoration and wildfire specifically, the predicted increases in pyro ersity and bio ersity. Given the importance of river and wetland ecosystems for bio ersity globally, a research priority should be to increase our understanding of potential mechanisms for a “triple win” of flood reduction, wildfire alleviation and bio ersity promotion.
Publisher: Wiley
Date: 25-02-2021
DOI: 10.1111/GCB.15539
Abstract: Globally, collapse of ecosystems—potentially irreversible change to ecosystem structure, composition and function—imperils bio ersity, human health and well‐being. We examine the current state and recent trajectories of 19 ecosystems, spanning 58° of latitude across 7.7 M km 2 , from Australia's coral reefs to terrestrial Antarctica. Pressures from global climate change and regional human impacts, occurring as chronic ‘presses’ and/or acute ‘pulses’, drive ecosystem collapse. Ecosystem responses to 5–17 pressures were categorised as four collapse profiles—abrupt, smooth, stepped and fluctuating. The manifestation of widespread ecosystem collapse is a stark warning of the necessity to take action. We present a three‐step assessment and management framework (3As Pathway Awareness , Anticipation and Action ) to aid strategic and effective mitigation to alleviate further degradation to help secure our future.
Publisher: Public Library of Science (PLoS)
Date: 02-10-2018
Publisher: Wiley
Date: 07-2022
DOI: 10.1002/ECS2.4159
Abstract: Fire regimes in North American forests are erse and modern fire records are often too short to capture important patterns, trends, feedbacks, and drivers of variability. Tree‐ring fire scars provide valuable perspectives on fire regimes, including centuries‐long records of fire year, season, frequency, severity, and size. Here, we introduce the newly compiled North American tree‐ring fire‐scar network (NAFSN), which contains 2562 sites, ,000 fire‐scarred trees, and covers large parts of North America. We investigate the NAFSN in terms of geography, s le depth, vegetation, topography, climate, and human land use. Fire scars are found in most ecoregions, from boreal forests in northern Alaska and Canada to subtropical forests in southern Florida and Mexico. The network includes 91 tree species, but is dominated by gymnosperms in the genus Pinus . Fire scars are found from sea level to ‐m elevation and across a range of topographic settings that vary by ecoregion. Multiple regions are densely s led (e.g., fire‐scarred trees), enabling new spatial analyses such as reconstructions of area burned. To demonstrate the potential of the network, we compared the climate space of the NAFSN to those of modern fires and forests the NAFSN spans a climate space largely representative of the forested areas in North America, with notable gaps in warmer tropical climates. Modern fires are burning in similar climate spaces as historical fires, but disproportionately in warmer regions compared to the historical record, possibly related to under‐s ling of warm subtropical forests or supporting observations of changing fire regimes. The historical influence of Indigenous and non‐Indigenous human land use on fire regimes varies in space and time. A 20th century fire deficit associated with human activities is evident in many regions, yet fire regimes characterized by frequent surface fires are still active in some areas (e.g., Mexico and the southeastern United States). These analyses provide a foundation and framework for future studies using the hundreds of thousands of annually‐ to sub‐annually‐resolved tree‐ring records of fire spanning centuries, which will further advance our understanding of the interactions among fire, climate, topography, vegetation, and humans across North America.
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/WF10121
Abstract: Increased wildfire activity in relation to future climate warming is likely for temperate rainforest biomes where fire depends on anomalously dry fuel conditions. Tree-ring fire history records were developed from fires scars in western Patagonia, and synchrony in fire activity was examined to determine the role of regional climate variability in promoting fires. Interannual variability in the multicentury fire history records was related to El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and the Southern Annular Mode (SAM). Interannual fire synchrony and decadal-scale trends in wildfires document a strong influence of broad-scale climatic variability on wildfires in western Patagonia. SAM is above average during years of regional drought that coincide with widespread fires. Analyses of contingent interactions of ENSO, PDO and SAM revealed that fire frequencies were greater than expected only when SAM was in its positive phase, regardless of the phase of ENSO and PDO. The fire-enhancing influence of SAM was greatest when PDO was also positive, which indicates Pacific-wide warmer conditions. There is a strong increase in wildfire activity coincident with warming and drying trends during the 20th century and with variability in SAM, which is predicted to continue to be in this fire-conducive phase for the 21st century.
Publisher: Public Library of Science (PLoS)
Date: 10-04-2020
Publisher: Frontiers Media SA
Date: 20-05-2022
Abstract: Infrequent stand-replacing wildfires are characteristic of mesic and/or cool conifer forests in western North America, where forest recovery within high-severity burn patch interiors can be slow, yet successful over long temporal periods (decades to centuries). Increasing fire frequency and high-severity burn patch size, under a warming climate, however, may challenge post-fire forest recovery, promoting landscape-level shifts in forest structure, composition, and distribution of non-forest patches. Crucial to a delay and/or impediment to this shift, fire refugia (i.e., remnant seed sources) may determine forest recovery trajectories and potential forest state-transitions. To examine how fire refugia attributes (i.e. extent, composition, and structure) interact with local climate and environmental conditions to determine post-fire forest recovery responses, we developed fine-grain maps of fire refugia via remote sensing and conducted field-based assessment of post-fire conifer tree establishment largely originating (i.e., dispersed) from fire refugium in the Central Cascade Range of the Pacific Northwest United States. We found that limitations on seed availability, represented by the distance 2 -weighted density (D 2 WD) of fine-grain refugia extent, largely explained post-fire tree establishment responses within our relatively mesic and cool subalpine study sites. Interactions between seed availability, climate, and environmental conditions indicated that the structural attributes of refugia (e.g., tree height) and site abiotic/biotic environmental controls (e.g., climate water deficit, canopy cover, and coarse woody debris cover) interplayed to constrain or enhance species-specific tree establishment responses. Importantly, these interactions illustrate that when seed availability is critically low for a given area, climate-environment conditions may strongly determine whether forests recover following fire(s). Toward modelling and predicting tree establishment responses and potential forest state-transitions after large stand-replacing fires(s), our study demonstrates the importance of accurately quantifying seed availability via the fine-grain extent, configuration, and attributes of remnant seed source legacies.
Publisher: Springer Science and Business Media LLC
Date: 04-06-2023
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/WF07152
Abstract: The present synthesis addresses key questions about several extreme fire events that occurred in the Nothofagus forest region of southern Argentina and Chile in the late 1990s and early 2000s: (1) are there historical precedents for the extent and severity of these recent wildfires? (2) To what extent can large, severe fires be attributed to influences from modern humans, either indirectly through land-use practices or directly through ignition? (3) What are the relationships of these fire events to interannual climatic variability and trends? (4) What are the medium-term ecological consequences of these fire events, particularly in terms of the resiliency of the burned ecosystems? Historic fire regimes vary greatly across the different ecosystem types in the southern Andean region, and the tree-ring record shows that before the 20th century, large severe fires also played a significant ecological role in shaping even the wettest forests. Recent severe droughts at an annual time scale have been facilitated by a trend towards higher temperatures since the mid-1970s. In large parts of the region, the risk of wildfire ignition and spread has been exacerbated by increases in lightning associated with higher temperatures, increased ignitions associated with exurban development, and conversion of less flammable native vegetation to more flammable plantations of exotic conifers.
Publisher: Wiley
Date: 11-2012
DOI: 10.1890/ES12-00234.1
Publisher: Elsevier BV
Date: 08-2022
Start Date: 2018
End Date: 2020
Funder: Directorate for Social, Behavioral & Economic Sciences
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Funder: Directorate for Social, Behavioral & Economic Sciences
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Funder: Directorate for Social, Behavioral & Economic Sciences
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Funder: Directorate for Geosciences
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