Climate, lightning ignitions, and fire severity in Yosemite National Park, California, USA

2009 ◽  
Vol 18 (7) ◽  
pp. 765 ◽  
Author(s):  
James A. Lutz ◽  
Jan W. van Wagtendonk ◽  
Andrea E. Thode ◽  
Jay D. Miller ◽  
Jerry F. Franklin
Keyword(s):  
National Park ◽  
Fire Severity ◽  
Fire Spread ◽  
Yosemite National Park ◽  
Large Area ◽  
Lightning Strikes ◽  
Continental Scale ◽  
Area Burned ◽  
Large Fires ◽  
In Fire

Continental-scale studies of western North America have attributed recent increases in annual area burned and fire size to a warming climate, but these studies have focussed on large fires and have left the issues of fire severity and ignition frequency unaddressed. Lightning ignitions, any of which could burn a large area given appropriate conditions for fire spread, could be the first indication of more frequent fire. We examined the relationship between snowpack and the ignition and size of fires that occurred in Yosemite National Park, California (area 3027 km2), between 1984 and 2005. During this period, 1870 fires burned 77 718 ha. Decreased spring snowpack exponentially increased the number of lightning-ignited fires. Snowpack mediated lightning-ignited fires by decreasing the proportion of lightning strikes that caused lightning-ignited fires and through fewer lightning strikes in years with deep snowpack. We also quantified fire severity for the 103 fires >40 ha with satellite fire-severity indices using 23 years of Landsat Thematic Mapper data. The proportion of the landscape that burned at higher severities and the complexity of higher-severity burn patches increased with the log10 of annual area burned. Using one snowpack forecast, we project that the number of lightning-ignited fires will increase 19.1% by 2020 to 2049 and the annual area burned at high severity will increase 21.9%. Climate-induced decreases in snowpack and the concomitant increase in fire severity suggest that existing assumptions may be understated – fires may become more frequent and more severe.

Landscape-scale effects of fire severity on mixed-conifer and red fir forest structure in Yosemite National Park

2013 ◽  
Vol 287 ◽  
pp. 17-31 ◽  
Author(s):  
Van R. Kane ◽  
James A. Lutz ◽  
Susan L. Roberts ◽  
Douglas F. Smith ◽  
Robert J. McGaughey ◽  
...  
Keyword(s):  
Forest Structure ◽  
National Park ◽  
Scale Effects ◽  
Fire Severity ◽  
Landscape Scale ◽  
Yosemite National Park ◽  
Mixed Conifer

scholarly journals Modeling the Effects of Fire Severity and Spatial Complexity on Small Mammals in Yosemite National Park, California

Fire Ecology ◽  
2008 ◽  
Vol 4 (2) ◽  
pp. 83-104 ◽  
Author(s):  
Susan L. Roberts ◽  
Jan W. van Wagtendonk ◽  
A. Keith Miles ◽  
Douglas A. Kelt ◽  
James A. Lutz
Keyword(s):  
Small Mammals ◽  
National Park ◽  
Fire Severity ◽  
Yosemite National Park ◽  
Spatial Complexity

Quantifying the fire regime distributions for severity in Yosemite National Park, California, USA

2011 ◽  
Vol 20 (2) ◽  
pp. 223 ◽  
Author(s):  
Andrea E. Thode ◽  
Jan W. van Wagtendonk ◽  
Jay D. Miller ◽  
James F. Quinn
Keyword(s):  
Sierra Nevada ◽  
National Park ◽  
Fire Regime ◽  
Fire Severity ◽  
Fire Regimes ◽  
Montane Forest ◽  
Subalpine Forest ◽  
Yosemite National Park ◽  
Forest Zone ◽  
Frequency Distributions

This paper quantifies current fire severity distributions for 19 different fire-regime types in Yosemite National Park, California, USA. Landsat Thematic Mapper remote sensing data are used to map burn severity for 99 fires (cumulatively over 97 000 ha) that burned in Yosemite over a 20-year period. These maps are used to quantify the frequency distributions of fire severity by fire-regime type. A classification is created for the resultant distributions and they are discussed within the context of four vegetation zones: the foothill shrub and woodland zone; the lower montane forest zone; the upper montane forest zone and the subalpine forest zone. The severity distributions can form a building block from which to discuss current fire regimes across the Sierra Nevada in California. This work establishes a framework for comparing the effects of current fires on our landscapes with our notions of how fires historically burned, and how current fire severity distributions differ from our desired future conditions. As this process is refined, a new set of information will be available to researchers and land managers to help understand how fire regimes have changed from the past and how we might attempt to manage them in the future.

scholarly journals An assessment of the implementation and outcomes of recent changes to fire management in the Kruger National Park

Koedoe ◽  
2008 ◽  
Vol 50 (1) ◽  
Author(s):  
Brian W. Van Wilgen ◽  
Navashni Govender ◽  
Sandra MacFadyen
Keyword(s):  
National Park ◽  
Fire Management ◽  
Fire Regime ◽  
Kruger National Park ◽  
Fire Intensity ◽  
Target Area ◽  
Large Fires ◽  
Sufficient Degree ◽  
Burnt Areas ◽  
In Fire

This paper reviews recent changes in fire management in the Kruger National Park, and assesses the resulting fire patterns against thresholds of potential concern. In 2002, a lightning-driven approach was replaced by an approach that combined point ignitions with unplanned and lightning fires. The approach aimed to burn an annual target area, determined by rainfall and fuel conditions, in point-ignition fires of different sizes. Most of the original fire-related thresholds of potential concern (TPCs) were incorporated into the new approach. The annual target area to be burnt ranged from 12 to 24% of the park between 2002 and 2006. The total area burnt generally exceeded the targets each year, and management fires accounted for less than half of the total area burnt. The fire regime was dominated by very large fires (> 5 000 ha) which accounted for 77% of the total area burnt. New TPCs were developed to assess whether the fire regime encompassed a sufficient degree of variability, in terms of fire intensity and the spatial distribution of burnt areas. After assessment and adjustment, it appears that these TPCs have not yet been exceeded. The point-ignition approach, and its evaluation in terms of variability and heterogeneity, is based on the untested assumption that a diverse fire regime will promote biodiversity. This assumption needs to be critically assessed. We recommend that the practice of point ignitions be continued, but that greater efforts be made to burn larger areas earlier in the season to reduce large and intense dry-season fires.

The effect of fire severity level on postfire recovery of hazel and raspberry in east-central Alberta

1985 ◽  
Vol 63 (4) ◽  
pp. 672-677 ◽  
Author(s):  
Mark Johnston ◽  
Paul Woodard
Keyword(s):  
Prescribed Fire ◽  
National Park ◽  
Fire Severity ◽  
Fire Effects ◽  
Height Growth ◽  
Fuel Load ◽  
East Central ◽  
Corylus Cornuta ◽  
Number Of Leaves ◽  
In Fire

A study of the effects of fire on the regrowth of beaked hazel (Corylus cornuta Marsh.) and wild red raspberry (Rubus strigosus Michx.) was carried out in Elk Island National Park, Alberta. Shrubs growing under an aspen stand were subjected to five levels of fire severity by artificially adjusting the fuel load on small plots within a larger prescribed fire. Effects studied included mortality, number of stem sprouts, height growth of sprouts, and number of leaves per sprout, all during the first growing season, and biomass after the second season. Generally, fire killed the shrub stems at all severity levels. Variation in fire severity had little significant effect on regrowth, except that lower levels seemed to favor higher numbers of hazel sprouts and increased raspberry height growth.

Landscape heterogeneity following large fires: insights from Yellowstone National Park, USA

2008 ◽  
Vol 17 (6) ◽  
pp. 742 ◽  
Author(s):  
Tania Schoennagel ◽  
Erica A. H. Smithwick ◽  
Monica G. Turner
Keyword(s):  
Yellowstone National Park ◽  
National Park ◽  
Multiple Scales ◽  
Landscape Heterogeneity ◽  
Fire Severity ◽  
Stand Age ◽  
Northern Rocky Mountains ◽  
C Storage ◽  
Fire Patterns ◽  
Large Fires

We characterised the remarkable heterogeneity following the large, severe fires of 1988 in Yellowstone National Park (YNP), in the northern Rocky Mountains, Wyoming, USA, by focussing on spatial variation in post-fire structure, composition and ecosystem function at broad, meso, and fine scales. Ecological heterogeneity at multiple scales may enhance resilience to large, severe disturbances by providing structural, biological and functional redundancy. Post-fire heterogeneity in stand age, coarse wood abundance, microbial and understorey communities reflected interactions between existing pre-fire patterns and fire severity at different scales, suggesting that environmental context plays an important role in successional responses to large fires. In response to these post-fire patterns, heterogeneity in carbon (C) and nitrogen (N) storage, N mineralisation, decomposition, and productivity was also evident at multiple scales and may confer resiliency to large fires. For example, at broad scales, C storage in YNP appears resistant to changes in age-class structure associated with large stand-replacing fires. In summary, the YNP landscape is recovering rapidly from the 1988 fires through natural mechanisms, owing to the abundance and spatial heterogeneity of post-fire residuals, but other systems with fewer biotic legacies may be less resilient to such large, severe fires.

A computational method for optimising fuel treatment locations

2007 ◽  
Vol 16 (6) ◽  
pp. 702 ◽  
Author(s):  
Mark A. Finney
Keyword(s):  
Fire Spread ◽  
Time Algorithm ◽  
Computational Method ◽  
Fire Growth ◽  
Spread Rate ◽  
Fuel Treatment ◽  
Large Fires ◽  
Random Patterns ◽  
In Fire ◽  
Weather Scenario

Modelling and experiments have suggested that spatial fuel treatment patterns can influence the movement of large fires. On simple theoretical landscapes consisting of two fuel types (treated and untreated), optimal patterns can be analytically derived that disrupt fire growth efficiently (i.e. with less area treated than random patterns). Although conceptually simple, the application of these theories to actual landscapes is made difficult by heterogeneity (fuels, weather, and topography). Here a computational method is described for heterogeneous landscapes that identifies efficient fuel treatment units and patterns for a selected fire weather scenario. The method requires input of two sets of spatial input data: (1) the current fuel conditions; and (2) the potential fuel conditions after a treatment is conducted (if treatment is permitted in a particular location). The contrast in fire spread rate between the two landscapes under the weather scenario conditions indicates where treatments are effective at delaying the growth of fires. Fire growth from the upwind edge of the landscape is then computed using a minimum travel time algorithm. This identifies major fire travel routes (areas needing treatment) and their intersections with the areas where treatments occurred and reduced the spread rate (opportunity for treatment). These zones of treatment ‘need and opportunity’ are iteratively delineated by contiguous patches of raster cells up to a user-supplied constraint on percentage of land area to be treated. This algorithm is demonstrated for simple and for complex landscapes.

Fire-regime changes in Canada over the last half century

2019 ◽  
Vol 49 (3) ◽  
pp. 256-269 ◽  
Author(s):  
Chelene C. Hanes ◽  
Xianli Wang ◽  
Piyush Jain ◽  
Marc-André Parisien ◽  
John M. Little ◽  
...  
Keyword(s):  
Fire Regime ◽  
Fire Regimes ◽  
Fire Season ◽  
Western Canada ◽  
Half Century ◽  
Regime Changes ◽  
Area Burned ◽  
Active Fire ◽  
Large Fires ◽  
In Fire

Contemporary fire regimes of Canadian forests have been well documented based on forest fire records between the late 1950s to 1990s. Due to known limitations of fire datasets, an analysis of changes in fire-regime characteristics could not be easily undertaken. This paper presents fire-regime trends nationally and within two zonation systems, the homogeneous fire-regime zones and ecozones, for two time periods, 1959–2015 and 1980–2015. Nationally, trends in both area burned and number of large fires (≥200 ha) have increased significantly since 1959, which might be due to increases in lightning-caused fires. Human-caused fires, in contrast, have shown a decline. Results suggest that large fires have been getting larger over the last 57 years and that the fire season has been starting approximately one week earlier and ending one week later. At the regional level, trends in fire regimes are variable across the country, with fewer significant trends. Area burned, number of large fires, and lightning-caused fires are increasing in most of western Canada, whereas human-caused fires are either stable or declining throughout the country. Overall, Canadian forests appear to have been engaged in a trajectory towards more active fire regimes over the last half century.

Pathways for climate change effects on fire: Models, data, and uncertainties

2011 ◽  
Vol 35 (3) ◽  
pp. 393-407 ◽  
Author(s):  
Amy E. Hessl
Keyword(s):  
Climate Change ◽  
Fire History ◽  
Wildland Fire ◽  
Fire Severity ◽  
Empirical Studies ◽  
Large Body ◽  
Fire Regimes ◽  
Area Burned ◽  
Frequency Changes ◽  
In Fire

Fire is a global process affecting both the biosphere and the atmosphere. As a result, measuring rates of change in wildland fire and understanding the mechanisms responsible for such changes are important research goals. A large body of modeling studies projects increases in wildfire activity in future decades, but few empirical studies have documented change in modern fire regimes. Identifying generalizable pathways through which climate change may alter fire regimes is a critical next step for understanding, measuring, and modeling fire under a changing climate. In this progress report, I review recent model-, empirical-, and fire history-based studies of fire and climate change and propose three pathways along which fire regimes might respond to climate change: changes in fuel condition, fuel volume, and ignitions. Model- and empirical-based studies have largely focused on changes in fuel condition with some models projecting up to 50% increases in area burned under a 2 x CO2 climate. Fire history data derived from tree-rings, sediment charcoal, and soil charcoal have helped identify past trajectories of change in fire regimes and can point to possible future conditions. However, most fire history research has focused on changes in area burned and fire frequency. Changes in fire severity may be equally important for the earth system and require further attention. Critical research needs include next generation dynamic vegetation models (DGVMs) that consider changes in vegetation alongside changes in human activities and long fire history records from a variety of vegetation types suitable for validating these DGVMs.

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