Mapping fuels in Yosemite National Park

2013 ◽  
Vol 43 (1) ◽  
pp. 7-17 ◽  
Author(s):  
Seth H. Peterson ◽  
Janet Franklin ◽  
Dar A. Roberts ◽  
Jan W. van Wagtendonk

Decades of fire suppression have led to unnaturally large accumulations of fuel in some forest communities in the western United States, including those found in lower and midelevation forests in Yosemite National Park in California. We employed the Random Forests decision tree algorithm to predict fuel models as well as 1-h live and 1-, 10-, and 100-h dead fuel loads using a suite of climatic, topographic, remotely sensed, and burn history predictor variables. Climate variables and elevation consistently were most useful for predicting all types of fuels, but remotely sensed variables increased the kappa accuracy metric by 5%–12% age points in each case, demonstrating the utility of using disparate data sources in a topographically diverse region dominated by closed-canopy vegetation. Fire history information (time-since-fire) generally only increased kappa by 1% age point, and only for the largest fuel classes. The Random Forests models were applied to the spatial predictor layers to produce maps of fuel models and fuel loads, and these showed that fuel loads are highest in the low-elevation forests that have been most affected by fire suppression impacting the natural fire regime.

2016 ◽  
Vol 25 (8) ◽  
pp. 909
Author(s):  
Raphaël D. Chavardès ◽  
Lori D. Daniels

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.


1994 ◽  
Vol 4 (3) ◽  
pp. 143 ◽  
Author(s):  
JK Brown ◽  
LS Bradshaw

Total particulate matter (PM) emissions were estimated for recent fires (1979-1990) and the presettlement period (prior to 1935) in the Selway-Bitterroot Wilderness (SBW) in Idaho and Montana. Recent period emissions were calculated by 10-day periods for surface fire and crown fire based on estimates of percentage fuel consumption and emission factors applied to fuel models constructed for each of eight fire regime types. Presettlement emissions were derived from estimates of historical fire occurrence. The occurrence and duration of smoke episodes in a large adjoining valley were documented for a 30-year period (1960-1990). During the presettlement period, smoke emissions were 1.3 times greater than during the recent period. Dispersion modeling indicated that during presettlement, visibility averaged 25% less than during the recent period. Valley smoke episodes ranged from 2 to 10 days in length and were 1.3 times more likely to occur during the presettlement period. Regression analysis indicated that a valley smoke event was likely above a 10-day PM threshold of 1,500 Mg. Characteristics of smoke episodes were described for none, minor, moderate, and extreme smoke categories. Occurrence of smoke did not differ between periods of full fire suppression and prescribed natural fire management.


2014 ◽  
Vol 23 (6) ◽  
pp. 781 ◽  
Author(s):  
Jennifer L. Clear ◽  
Chiara Molinari ◽  
Richard H. W. Bradshaw

Natural disturbance dynamics, such as fire, have a fundamental control on forest composition and structure. Knowledge of fire history and the dominant drivers of fire are becoming increasingly important for conservation and management practice. Temporal and spatial variability in biomass burning is examined here using 170 charcoal and 15 fire scar records collated throughout Fennoscandia and Denmark. The changing fire regime is discussed in relation to local biogeographical controls, regional climatic change, anthropogenic land use and fire suppression. The region has experienced episodic variability in the dominant drivers of biomass burning throughout the Holocene, creating a frequently changing fire regime. Early Holocene biomass burning appears to be driven by fuel availability. Increased continentality during the mid-Holocene Thermal Maximum coincides with an increase in fire. The mid–late Holocene front-like spread of Picea abies (Norway spruce) and cooler, wetter climatic conditions reduce local biomass burning before the onset of intensified anthropogenic land use, and the late Holocene increase in anthropogenic activity created artificially high records of biomass burning that overshadowed the natural fire signal. An economic shift from extensive subsistence land use to agriculture and forestry as well as active fire suppression has reduced regional biomass burning. However, it is proposed that without anthropogenic fire suppression, the underlying natural fire signal would remain low because of the now widespread dominance of P. abies.


2016 ◽  
Vol 25 (4) ◽  
pp. 433 ◽  
Author(s):  
Raphaël D. Chavardès ◽  
Lori D. Daniels

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.


Fire Ecology ◽  
2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Jan W. van Wagtendonk ◽  
Peggy E. Moore ◽  
Julie L. Yee ◽  
James A. Lutz

Abstract Background The effects of climate on plant species ranges are well appreciated, but the effects of other processes, such as fire, on plant species distribution are less well understood. We used a dataset of 561 plots 0.1 ha in size located throughout Yosemite National Park, in the Sierra Nevada of California, USA, to determine the joint effects of fire and climate on woody plant species. We analyzed the effect of climate (annual actual evapotranspiration [AET], climatic water deficit [Deficit]) and fire characteristics (occurrence [BURN] for all plots, fire return interval departure [FRID] for unburned plots, and severity of the most severe fire [dNBR]) on the distribution of woody plant species. Results Of 43 species that were present on at least two plots, 38 species occurred on five or more plots. Of those 38 species, models for the distribution of 13 species (34%) were significantly improved by including the variable for fire occurrence (BURN). Models for the distribution of 10 species (26%) were significantly improved by including FRID, and two species (5%) were improved by including dNBR. Species for which distribution models were improved by inclusion of fire variables included some of the most areally extensive woody plants. Species and ecological zones were aligned along an AET-Deficit gradient from cool and moist to hot and dry conditions. Conclusions In fire-frequent ecosystems, such as those in most of western North America, species distribution models were improved by including variables related to fire. Models for changing species distributions would also be improved by considering potential changes to the fire regime.


Author(s):  
Kendra McLauchlan ◽  
Kyleen Kelly

One of the keystone tree species in subalpine forests of the western United States – whitebark pine (Pinus albicaulis, hereafter whitebark pine) – is experiencing a significant mortality event (Millar et al. 2012). Whitebark pine occupies a relatively restricted range in the high-elevation ecosystems in the northern Rockies and its future is uncertain. The current decline of whitebark pine populations has been attributed to pine beetle infestations, blister rust infections, anthropogenic fire suppression, and climate change (Millar et al. 2012). Despite the knowledge that whitebark pine is severely threatened by multiple stressors, little is known about the historic capacity of this species to handle these stressors. More specifically, it is unknown how whitebark pine has dealt with past climatic variability, particularly variation in the type of precipitation (rain vs. snow) available for soil moisture, and how differences in quantity of precipitation have influenced the establishment and growth of modern stands. We propose to study the past responses of whitebark pine to paleoclimatic conditions, which would be useful to park ecologists in developing new conservation and regeneration plans to prevent the extinction of this already severely threatened high-elevation resource. The purpose of this study is to determine in great temporal and spatial detail the demographics of the current stand of whitebark pine trees in the watershed surrounding an unnamed, high-altitude pond (known informally as Whitebark Pine Moraine Pond) located approximately 3.06 miles NW of Jenny Lake in Grand Teton National Park (GTNP). The main objectives of this study were: 1.) To obtain the precise GPS locations of the current stand of whitebark pine trees in the watershed to generate a GIS map detailing their locations. 2.) To obtain increment cores of a subset of the trees in the watershed to estimate age and date of establishment for the current stand of whitebark pines, with particular attention to fire history. 3.) To analyze ring widths from core samples to identify climatic indicators that may influence the regeneration and survival of whitebark pine.


2020 ◽  
Vol 9 (5) ◽  
pp. 333
Author(s):  
Nicole C. Inglis ◽  
Jelena Vukomanovic

Fire management in protected areas faces mounting obstacles as climate change alters disturbance regimes, resources are diverted to fighting wildfires, and more people live along the boundaries of parks. Evidence-based prescribed fire management and improved communication with stakeholders is vital to reducing fire risk while maintaining public trust. Numerous national fire databases document when and where natural, prescribed, and human-caused fires have occurred on public lands in the United States. However, these databases are incongruous and non-standardized, making it difficult to visualize spatiotemporal patterns of fire and engage stakeholders in decision-making. We created interactive decision analytics (“VISTAFiRe”) that transform fire history data into clear visualizations of the spatial and temporal dimensions of fire and its management. We demonstrate the utility of our approach using Big Cypress National Preserve and Everglades National Park as examples of protected areas experiencing fire regime change between 1980 and 2017. Our open source visualizations may be applied to any data from the National Park Service Wildland Fire Events Geodatabase, with flexibility to communicate shifts in fire regimes over time, such as the type of ignition, duration and magnitude, and changes in seasonal occurrence. Application of the tool to Everglades and Big Cypress revealed that natural wildfires are occurring earlier in the wildfire season, while human-caused and prescribed wildfires are becoming less and more common, respectively. These new avenues of stakeholder communication are allowing the National Park Service to devise research plans to prepare for environmental change, guide resource allocation, and support decision-making in a clear and timely manner.


2007 ◽  
Vol 13 (3) ◽  
pp. 177 ◽  
Author(s):  
Owen Price ◽  
Bryan Baker

A nine year fire history for the Darwin region was created from Landsat imagery, and examined to describe the fire regime across the region. 43% of the region burned each year, and approximately one quarter of the fires occur in the late dry season, which is lower than most other studied areas. Freehold land, which covers 35% of the greater Darwin region, has 20% long-unburnt land. In contrast, most publicly owned and Aboriginal owned land has very high fire frequency (60-70% per year), and only 5% long unburnt. It seems that much of the Freehold land is managed for fire suppression, while the common land is burnt either to protect the Freehold or by pyromaniacs. Generalized Linear Modelling among a random sample of points revealed that fire frequency is higher among large blocks of savannah vegetation, and at greater distances from mangrove vegetation and roads. This suggests that various kinds of fire break can be used to manage fire in the region. The overall fire frequency in the Darwin region is probably too high and is having a negative impact on wildlife. However, the relatively low proportion of late dry season fires means the regime is probably not as bad as in some other regions. The management of fire is ad-hoc and strongly influenced by tenure. There needs to be a clear statement of regional fire targets and a strategy to achieve these. Continuation of the fire mapping is an essential component of achieving the targets.


2016 ◽  
Vol 113 (48) ◽  
pp. 13684-13689 ◽  
Author(s):  
Alan H. Taylor ◽  
Valerie Trouet ◽  
Carl N. Skinner ◽  
Scott Stephens

Large wildfires in California cause significant socioecological impacts, and half of the federal funds for fire suppression are spent each year in California. Future fire activity is projected to increase with climate change, but predictions are uncertain because humans can modulate or even override climatic effects on fire activity. Here we test the hypothesis that changes in socioecological systems from the Native American to the current period drove shifts in fire activity and modulated fire–climate relationships in the Sierra Nevada. We developed a 415-y record (1600–2015 CE) of fire activity by merging a tree-ring–based record of Sierra Nevada fire history with a 20th-century record based on annual area burned. Large shifts in the fire record corresponded with socioecological change, and not climate change, and socioecological conditions amplified and buffered fire response to climate. Fire activity was highest and fire–climate relationships were strongest after Native American depopulation—following mission establishment (ca. 1775 CE)—reduced the self-limiting effect of Native American burns on fire spread. With the Gold Rush and Euro-American settlement (ca. 1865 CE), fire activity declined, and the strong multidecadal relationship between temperature and fire decayed and then disappeared after implementation of fire suppression (ca. 1904 CE). The amplification and buffering of fire–climate relationships by humans underscores the need for parameterizing thresholds of human- vs. climate-driven fire activity to improve the skill and value of fire–climate models for addressing the increasing fire risk in California.


1990 ◽  
Vol 68 (8) ◽  
pp. 1763-1767 ◽  
Author(s):  
Alan M. Masters

Time-since-fire distribution analysis is used to estimate forest fire frequency for the 1400 km2 Kootenay National Park, British Columbia, located on the west slope of the Rocky Mountains. The time-since-fire distribution indicates three periods of different fire frequency: 1988 to 1928, 1928 to 1788, and before 1788. The fire cycle for the park was > 2700 years for 1988 to 1928, 130 years between 1928 and 1788, and 60 years between 1778 and 1508. Longer fire cycles after 1788 and 1928 may be due, respectively, to cool climate associated with the Little Ice Age and a recent period of higher precipitation. Contrary to some fire history investigations in the region, neither a fire suppression policy since park establishment in 1919, nor the completion of the Windermere Highway through the park in 1923 appear to have changed the fire frequency from levels during pre-European occupation. Spatial partitioning of the time-since-fire distribution was unsuccessful. No relationship was found between elevation or aspect and fire frequency. Key words: fire cycle, Rocky Mountains, climate change.


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