10 results on '"Kolden CA"'
Search Results
2. Projected increases in western US forest fire despite growing fuel constraints
- Author
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Abatzoglou, JT, Abatzoglou, JT, Battisti, DS, Williams, AP, Hansen, WD, Harvey, BJ, Kolden, CA, Abatzoglou, JT, Abatzoglou, JT, Battisti, DS, Williams, AP, Hansen, WD, Harvey, BJ, and Kolden, CA
- Abstract
Escalating burned area in western US forests punctuated by the 2020 fire season has heightened the need to explore near-term macroscale forest-fire area trajectories. As fires remove fuels for subsequent fires, feedbacks may impose constraints on the otherwise climate-driven trend of increasing forest-fire area. Here, we test how fire-fuel feedbacks moderate near-term (2021–2050) climate-driven increases in forest-fire area across the western US. Assuming constant fuels, climate–fire models project a doubling of forest-fire area compared to 1991–2020. Fire-fuel feedbacks only modestly attenuate the projected increase in forest-fire area. Even models with strong feedbacks project increasing interannual variability in forest-fire area and more than a two-fold increase in the likelihood of years exceeding the 2020 fire season. Fuel limitations from fire-fuel feedbacks are unlikely to strongly constrain the profound climate-driven broad-scale increases in forest-fire area by the mid-21st century, highlighting the need for proactive adaptation to increased western US forest-fire impacts.
- Published
- 2021
3. Vegetation fires in the Anthropocene
- Author
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Bowman, DMJS, Kolden, CA, Abatzoglou, JT, Johnston, FH, van der Werf, Guido, Flannigan, M, Bowman, DMJS, Kolden, CA, Abatzoglou, JT, Johnston, FH, van der Werf, Guido, and Flannigan, M
- Abstract
Vegetation fires are an essential component of the Earth system but can also cause substantial economic losses, severe air pollution, human mortality and environmental damage. Contemporary fire regimes are increasingly impacted by human activities and climate change, but, owing to the complex fire–human–climate interactions and incomplete historical or long-term datasets, it is difficult to detect and project fire-regime trajectories. In this Review, we describe recent global and regional trends in fire activity and examine projections for fire regimes in the near future. Although there are large uncertainties, it is likely that the economic and environmental impacts of vegetation fires will worsen as a result of anthropogenic climate change. These effects will be particularly prominent in flammable forests in populated temperate zones, the sparsely inhabited flammable boreal zone and fire-sensitive tropical rainforests, and will contribute to greenhouse gas emissions. The impacts of increased fire activity can be mitigated through effective stewardship of fire regimes, which should be achieved through evidence-based fire management that incorporates indigenous and local knowledge, combined with planning and design of natural and urban landscapes. Increasing transdisciplinary research is needed to fully understand how Anthropocene fire regimes are changing and how humans must adapt.
- Published
- 2020
- Full Text
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4. Climatic influences on interannual variability in regional burn severity across western US forests
- Author
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Abatzoglou, JT, Abatzoglou, JT, Kolden, CA, Williams, AP, Lutz, JA, Smith, AMS, Abatzoglou, JT, Abatzoglou, JT, Kolden, CA, Williams, AP, Lutz, JA, and Smith, AMS
- Abstract
Interannual variability in burn severity is assessed across forested ecoregions of the western United States to understand how it is influenced by variations in area burned and climate during 1984-2014. Strong correlations (r>0.6) between annual area burned and climate metrics were found across many of the studied regions. The burn severity of individual fires and fire seasons was weakly, but significantly (P<0.05), correlated with burned area across many regions. Interannual variability in fuel dryness evaluated with fuel aridity metrics demonstrated weak-to-moderate (r >0.4) relationships with regional burn severity, congruent with but weaker than those between climate and area burned for most ecoregions. These results collectively suggest that irrespective of other factors, long-term increases in fuel aridity will lead to increased burn severity in western United States forests for existing vegetation regimes.
- Published
- 2017
5. Death from hunger or thirst? Phloem death, rather than xylem hydraulic failure, as a driver of fire-induced conifer mortality.
- Author
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Partelli-Feltrin R, Smith AMS, Adams HD, Thompson RA, Kolden CA, Yedinak KM, and Johnson DM
- Subjects
- Phloem, Carbohydrates, Xylem physiology, Trees physiology, Water, Plant Stems, Hunger, Thirst
- Abstract
Disruption of photosynthesis and carbon transport due to damage to the tree crown and stem cambial cells, respectively, can cause tree mortality. It has recently been proposed that fire-induced dysfunction of xylem plays an important role in tree mortality. Here, we simultaneously tested the impact of a lethal fire dose on nonstructural carbohydrates (NSCs) and xylem hydraulics in Pinus ponderosa saplings. Saplings were burned with a known lethal fire dose. Nonstructural carbohydrates were assessed in needles, main stems, roots and whole plants, and xylem hydraulic conductivity was measured in the main stems up to 29 d postfire. Photosynthesis and whole plant NSCs declined postfire. Additionally, all burned saplings showed 100% phloem/cambium necrosis, and roots of burned saplings had reduced NSCs compared to unburned and defoliated saplings. We further show that, contrary to patterns observed with NSCs, water transport was unchanged by fire and there was no evidence of xylem deformation in saplings that experienced a lethal dose of heat from fire. We conclude that phloem and cambium mortality, and not hydraulic failure, were probably the causes of death in these saplings. These findings advance our understanding of the physiological response to fire-induced injuries in conifer trees., (© 2022 The Authors. New Phytologist © 2022 New Phytologist Foundation.)
- Published
- 2023
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6. Adapting western North American forests to climate change and wildfires: 10 common questions.
- Author
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Prichard SJ, Hessburg PF, Hagmann RK, Povak NA, Dobrowski SZ, Hurteau MD, Kane VR, Keane RE, Kobziar LN, Kolden CA, North M, Parks SA, Safford HD, Stevens JT, Yocom LL, Churchill DJ, Gray RW, Huffman DW, Lake FK, and Khatri-Chhetri P
- Subjects
- Climate Change, Forests, North America, Fires, Wildfires
- Abstract
We review science-based adaptation strategies for western North American (wNA) forests that include restoring active fire regimes and fostering resilient structure and composition of forested landscapes. As part of the review, we address common questions associated with climate adaptation and realignment treatments that run counter to a broad consensus in the literature. These include the following: (1) Are the effects of fire exclusion overstated? If so, are treatments unwarranted and even counterproductive? (2) Is forest thinning alone sufficient to mitigate wildfire hazard? (3) Can forest thinning and prescribed burning solve the problem? (4) Should active forest management, including forest thinning, be concentrated in the wildland urban interface (WUI)? (5) Can wildfires on their own do the work of fuel treatments? (6) Is the primary objective of fuel reduction treatments to assist in future firefighting response and containment? (7) Do fuel treatments work under extreme fire weather? (8) Is the scale of the problem too great? Can we ever catch up? (9) Will planting more trees mitigate climate change in wNA forests? And (10) is post-fire management needed or even ecologically justified? Based on our review of the scientific evidence, a range of proactive management actions are justified and necessary to keep pace with changing climatic and wildfire regimes and declining forest heterogeneity after severe wildfires. Science-based adaptation options include the use of managed wildfire, prescribed burning, and coupled mechanical thinning and prescribed burning as is consistent with land management allocations and forest conditions. Although some current models of fire management in wNA are averse to short-term risks and uncertainties, the long-term environmental, social, and cultural consequences of wildfire management primarily grounded in fire suppression are well documented, highlighting an urgency to invest in intentional forest management and restoration of active fire regimes., (© 2021 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of Ecological Society of America. This article has been contributed to by US Government employees and their work is in the public domain in the USA.)
- Published
- 2021
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7. The Fire and Tree Mortality Database, for empirical modeling of individual tree mortality after fire.
- Author
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Cansler CA, Hood SM, Varner JM, van Mantgem PJ, Agne MC, Andrus RA, Ayres MP, Ayres BD, Bakker JD, Battaglia MA, Bentz BJ, Breece CR, Brown JK, Cluck DR, Coleman TW, Corace RG 3rd, Covington WW, Cram DS, Cronan JB, Crouse JE, Das AJ, Davis RS, Dickinson DM, Fitzgerald SA, Fulé PZ, Ganio LM, Grayson LM, Halpern CB, Hanula JL, Harvey BJ, Kevin Hiers J, Huffman DW, Keifer M, Keyser TL, Kobziar LN, Kolb TE, Kolden CA, Kopper KE, Kreitler JR, Kreye JK, Latimer AM, Lerch AP, Lombardero MJ, McDaniel VL, McHugh CW, McMillin JD, Moghaddas JJ, O'Brien JJ, Perrakis DDB, Peterson DW, Prichard SJ, Progar RA, Raffa KF, Reinhardt ED, Restaino JC, Roccaforte JP, Rogers BM, Ryan KC, Safford HD, Santoro AE, Shearman TM, Shumate AM, Sieg CH, Smith SL, Smith RJ, Stephenson NL, Stuever M, Stevens JT, Stoddard MT, Thies WG, Vaillant NM, Weiss SA, Westlind DJ, Woolley TJ, and Wright MC
- Subjects
- Databases as Topic, United States, Fires, Forestry, Forests, Trees
- Abstract
Wildland fires have a multitude of ecological effects in forests, woodlands, and savannas across the globe. A major focus of past research has been on tree mortality from fire, as trees provide a vast range of biological services. We assembled a database of individual-tree records from prescribed fires and wildfires in the United States. The Fire and Tree Mortality (FTM) database includes records from 164,293 individual trees with records of fire injury (crown scorch, bole char, etc.), tree diameter, and either mortality or top-kill up to ten years post-fire. Data span 142 species and 62 genera, from 409 fires occurring from 1981-2016. Additional variables such as insect attack are included when available. The FTM database can be used to evaluate individual fire-caused mortality models for pre-fire planning and post-fire decision support, to develop improved models, and to explore general patterns of individual fire-induced tree death. The database can also be used to identify knowledge gaps that could be addressed in future research.
- Published
- 2020
- Full Text
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8. Human-environmental drivers and impacts of the globally extreme 2017 Chilean fires.
- Author
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Bowman DMJS, Moreira-Muñoz A, Kolden CA, Chávez RO, Muñoz AA, Salinas F, González-Reyes Á, Rocco R, de la Barrera F, Williamson GJ, Borchers N, Cifuentes LA, Abatzoglou JT, and Johnston FH
- Subjects
- Chile, Droughts, Humans, Weather, Fires, Pinus
- Abstract
In January 2017, hundreds of fires in Mediterranean Chile burnt more than 5000 km
2 , an area nearly 14 times the 40-year mean. We contextualize these fires in terms of estimates of global fire intensity using MODIS satellite record, and provide an overview of the climatic factors and recent changes in land use that led to the active fire season and estimate the impact of fire emissions to human health. The primary fire activity in late January coincided with extreme fire weather conditions including all-time (1979-2017) daily records for the Fire Weather Index (FWI) and maximum temperature, producing some of the most energetically intense fire events on Earth in the last 15-years. Fire activity was further enabled by a warm moist growing season in 2016 that interrupted an intense drought that started in 2010. The land cover in this region had been extensively modified, with less than 20% of the original native vegetation remaining, and extensive plantations of highly flammable exotic Pinus and Eucalyptus species established since the 1970s. These plantations were disproportionally burnt (44% of the burned area) in 2017, and associated with the highest fire severities, as part of an increasing trend of fire extent in plantations over the past three decades. Smoke from the fires exposed over 9.5 million people to increased concentrations of particulate air pollution, causing an estimated 76 premature deaths and 209 additional admissions to hospital for respiratory and cardiovascular conditions. This study highlights that Mediterranean biogeographic regions with expansive Pinus and Eucalyptus plantations and associated rural depopulation are vulnerable to intense wildfires with wide ranging social, economic, and environmental impacts, which are likely to become more frequent due to longer and more extreme wildfire seasons.- Published
- 2019
- Full Text
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9. Hazards in Motion: Development of Mobile Geofences for Use in Logging Safety.
- Author
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Zimbelman EG, Keefe RF, Strand EK, Kolden CA, and Wempe AM
- Subjects
- Algorithms, Computer Simulation, Equipment Safety, Geographic Information Systems, Humans, Occupational Health, Radio Waves, Safety, United States, Motion
- Abstract
Logging is one of the most hazardous occupations in the United States. Real-time positioning that uses global navigation satellite system (GNSS) technology paired with radio frequency transmission (GNSS-RF) has the potential to reduce fatal and non-fatal accidents on logging operations through the use of geofences that define safe work areas. Until recently, most geofences have been static boundaries. The aim of this study was to evaluate factors affecting mobile geofence accuracy in order to determine whether virtual safety zones around moving ground workers or equipment are a viable option for improving situational awareness on active timber sales. We evaluated the effects of walking pace, transmission interval, geofence radius, and intersection angle on geofence alert delay using a replicated field experiment. Simulation was then used to validate field results and calculate the proportion of GNSS error bearings resulting in early alerts. The interaction of geofence radius and intersection angle affected safety geofence alert delay in the field experiment. The most inaccurate alerts were negative, representing early warning. The magnitude of this effect was largest at the greatest intersection angles. Simulation analysis supported these field results and also showed that larger GNSS error corresponded to greater variability in alert delay. Increasing intersection angle resulted in a larger proportion of directional GNSS error that triggered incorrect, early warnings. Because the accuracy of geofence alerts varied greatly depending on GNSS error and angle of approach, geofencing for occupational safety is most appropriate for general situational awareness unless real-time correction methods to improve accuracy or higher quality GNSS-RF transponders are used.
- Published
- 2017
- Full Text
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10. Modeling the impacts of wildfire on runoff and pollutant transport from coastal watersheds to the nearshore environment.
- Author
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Morrison KD and Kolden CA
- Subjects
- Models, Theoretical, Oceans and Seas, Ecosystem, Fires, Water Movements, Water Pollutants, Chemical chemistry
- Abstract
Wildfire is a common disturbance that can significantly alter vegetation in watersheds and affect the rate of sediment and nutrient transport to adjacent nearshore oceanic environments. Changes in runoff resulting from heterogeneous wildfire effects are not well-understood due to both limitations in the field measurement of runoff and temporally-limited spatial data available to parameterize runoff models. We apply replicable, scalable methods for modeling wildfire impacts on sediment and nonpoint source pollutant export into the nearshore environment, and assess relationships between wildfire severity and runoff. Nonpoint source pollutants were modeled using a GIS-based empirical deterministic model parameterized with multi-year land cover data to quantify fire-induced increases in transport to the nearshore environment. Results indicate post-fire concentration increases in phosphorus by 161 percent, sediments by 350 percent and total suspended solids (TSS) by 53 percent above pre-fire years. Higher wildfire severity was associated with the greater increase in exports of pollutants and sediment to the nearshore environment, primarily resulting from the conversion of forest and shrubland to grassland. This suggests that increasing wildfire severity with climate change will increase potential negative impacts to adjacent marine ecosystems. The approach used is replicable and can be utilized to assess the effects of other types of land cover change at landscape scales. It also provides a planning and prioritization framework for management activities associated with wildfire, including suppression, thinning, and post-fire rehabilitation, allowing for quantification of potential negative impacts to the nearshore environment in coastal basins., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
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