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

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.

2012 ◽  
Vol 124 (1) ◽  
pp. 30
Author(s):  
Kevin G. Tolhurst

The Wombat Fire Effects Study was established to address a number of questions in relation to the effects of repeated low-intensity fires in mixed species eucalypt forest in the foothills of Victoria. This study has now been going for 25 years and has included the study of understorey plants, fuels, bats, terrestrial mammals, reptiles, invertebrates, fungi, birds, soils, tree growth, fire behaviour and weather. This forest system has shown a high resilience to fire that is attributed here to the patchiness and variability in the fire characteristics within a fire and the relatively small proportion of the landscape being affected. A means of comparing the level of “injury” caused by low-intensity prescribed fire with high intensity wildfire is proposed so that the debate about leverage benefits (the reduction in wildfire area compared to the area of planned burning) can be more rational. There are some significant implications for assessing the relative environmental impacts of wildfire compared with the planned burning program being implemented in Victoria since the Victorian Bushfires Royal Commission recommendations (Teague et al. 2010).


2002 ◽  
Vol 11 (1) ◽  
pp. 1 ◽  
Author(s):  
Jolie Pollet ◽  
Philip N. Omi

Fire exclusion policies have affected stand structure and wildfire hazard in north American ponderosa pine forests. Wildfires are becoming more severe in stands where trees are densely stocked with shade-tolerant understory trees. Although forest managers have been employing fuel treatment techniques to reduce wildfire hazard for decades, little scientific evidence documents the success of treatments in reducing fire severity. Our research quantitatively examined fire effects in treated and untreated stands in western United States national forests. Four ponderosa pine sites in Montana, Washington, California and Arizona were selected for study. Fuel treatments studied include: prescribed fire only, whole-tree thinning, and thinning followed by prescribed fire. On-the-ground fire effects were measured in adjacent treated and untreated forests. We developed post facto fire severity and stand structure measurement techniques to complete field data collection. We found that crown fire severity was mitigated in stands that had some type of fuel treatment compared to stands without any treatment. At all four of the sites, the fire severity and crown scorch were significantly lower at the treated sites. Results from this research indicate that fuel treatments, which remove small diameter trees, may be beneficial for reducing crown fire hazard in ponderosa pine sites.


Author(s):  
Monica Turner ◽  
Robert Gardner ◽  
William Romme

The 1988 fires that burned in Yellowstone National Park presented ecologists with a unique opportunity to investigate ecological responses to large-scale fires (Christensen et al. 1989, Knight and Wallace 1989). The Yellowstone fires created an extremely heterogeneous landscape in terms of both the overall burning patterns and the variable fire severity within burned areas. Large fires rarely consume the entire forest because of the influence of wind variations, topography, vegetation type, natural fire breaks, and the time of day that the fire passed through (Rowe and Scotter 1973, Wright and Heinselman 1973, Van Wagner 1983). Direct fire effects such as tree mortality and organic matter consumption are related to locally variable parameters such as moisture content (Brown et al. 1985, Peterson and Ryan 1986, Ryan et al. 1988), and fire severity and return intervals are often strongly influenced by topographic and edaphic variability (Habeck and Mutch 1973, Romme and Knight 1981, Hemstrom and Franklin 1982, Whitney 1986). Therefore, burned landscapes generally contain areas of low as well as high intensity fire, usually in a complex mosaic (Van Wagner 1983). These variable fire intensities result in a heterogeneous pattern of burn severities (effects of fire on the ecosystem), as well as islands of unburned vegetation. The influence of burn severity on plant reestablishment following fire is well documented (e.g., Lyon and Stickney 1976, Rowe and Scotter 1973, Viereck 1983, Ryan and Noste 1985), and the importance of the effects of limited burns and low-intensity fires on the vegetation mosaic has been recognized (Habeck and Mutch 1973, Rowe 1983). However, few studies have dealt explicitly with the spatial variation of fire effects in a systematic and quantitative way.


2013 ◽  
Vol 22 (5) ◽  
pp. 615 ◽  
Author(s):  
K. Wanthongchai ◽  
V. Tarusadamrongdet ◽  
K. Chinnawong ◽  
K. Sooksawat

Anthropogenic burning has become a common phenomenon throughout Thailand’s pine-dominated ecosystems. This study investigated fuel loads and experimental fire behaviour characteristics in a degraded pine forest (PF) and a pine–oak forest (O-PF), at Nam Nao National Park, Thailand in three replicate 50 × 50-m plots of each forest type. Pre-burn fuel loads, fire behaviour descriptors, fire and soil temperature, the residues left after burning and post-burn fuel recovery for 1 year were investigated. The aboveground fuel load in PF (1.29 kg m–2) was significantly higher than in O-PF (0.87 kg m–2). The main fuel components in the PF stand were grass (45%) and litter (44%), whereas leaf litter was the predominant fuel in the O-PF stand (55%). The fire behaviour characteristics in the PF stand were significantly greater than those in the O-PF stand. Burning at the O-PF and the PF was respectively classified as low (48 kW m–1) and medium intensity (627 kW m–1). During the burning experiment, the surface soil temperatures at all sites were higher than 250°C. However, fire did not cause temperature changes in the deeper soil layers. In the pine forest the post-burn fuel loads 1 year after the fire remained lower than the pre-burn level. These results may imply that a pine forest at Nam Nao National Park requires more than 1 year of fire-free period to recover back to the pre-burn conditions.


2019 ◽  
Vol 49 (8) ◽  
pp. 1004-1014 ◽  
Author(s):  
Calvin J. Maginel ◽  
Benjamin O. Knapp ◽  
John M. Kabrick ◽  
Rose-Marie Muzika

Landscape-scale prescribed burning may be appealing for natural community restoration due to operational efficiency and possible heterogeneity in fire effects across broad spatial scales. We monitored plant community responses for >15 years with variable prescribed fire frequencies applied across a Missouri Ozarks landscape stratified into distinct ecological site types. Through the study period, burning had no effect on the overstory tree density or basal area. Midstory stem densities decreased rapidly in periodically burned units and more gradually with annual fire. Burning increased total ground flora cover and the cover of forbs, grasses, and legumes. The effect of burning on species richness differed among site types, with increased species richness through time on exposed slopes. There was no effect of prescribed burning on species richness on two of three protected slope site types, and annual burning decreased species richness in upland waterways. Among the site types, the upland waterways had the most species associated with pre-burn communities. We conclude that (i) burning consistently increased cover of ground layer vegetation across the landscape, while decreasing the midstory stem densities, and (ii) site type moderated ground flora richness response, with more pronounced effects of prescribed burning on exposed sites than on protected sites.


Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Susan C. Loeb ◽  
Rachel V. Blakey

Abstract Background Bats are important components of forested ecosystems and are found in forests worldwide. Consequently, they often interact with fire. Previous reviews of the effects of fire on bats have focused on prescribed fire effects, in part due to the limited number of studies on bat responses to wildfire. However, over the past several years, studies on bat responses to wildfire and prescribed fire have increased considerably. We reviewed this rapidly expanding body of literature to determine whether bats respond differently to prescribed fire and wildfire, and the important factors driving those differences. We also examined regional similarities and differences in bat response to prescribed fire and wildfire and identified areas in need of further research. Results Our review included 52 studies (29 prescribed fire, 23 wildfire) from North and South America, Europe, Australia, and Africa, although studies from Europe, South America, and Africa were limited. In general, we found that bats show positive or neutral responses to prescribed fire, whereas a greater proportion of negative responses were reported for wildfire. However, some of the negative responses to wildfire are short-lived or local, suggesting that bats may be resilient to the effects of fire. Factors such as fire severity, fire frequency, time since last burn, burn extent, season of burn, and pyrodiversity were all found to be important drivers of bats’ responses to both prescribed fire and wildfire. Conclusions The importance of the spatial and temporal aspects of fire suggests that these factors need to be considered when designing future studies and interpreting results. Pyrodiversity may be a particularly important concept to further our understanding of bats’ responses to fire. We found several gaps in our knowledge including lack of information on direct effects of fire (e.g., mortality), regional and taxonomic biases, effects of wildfire on roosting habitat, and the effects of climate change. Although current studies suggest that fire may be an important management tool for improving bat habitat, the threat of more frequent, extensive, and severe wildfires may put additional stress on some bat populations, particularly those being impacted by disease, habitat loss and fragmentation, and climate change.


2009 ◽  
Vol 18 (7) ◽  
pp. 765 ◽  
Author(s):  
James A. Lutz ◽  
Jan W. van Wagtendonk ◽  
Andrea E. Thode ◽  
Jay D. Miller ◽  
Jerry F. Franklin

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.


Fire ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 37
Author(s):  
Renaud Mathieu ◽  
Russell Main ◽  
David P. Roy ◽  
Laven Naidoo ◽  
Hannah Yang

Savannahs are mixed woody-grass communities where low-intensity surface fires are common, affecting mostly the grass layer and rarely damaging trees. We investigated the effect of surface fires in a savannah system in the Kruger National Park, South Africa, on the backscatter of synthetic aperture radar (SAR) C-band Sentinel-1A images. Pre-fire and post-fire dual polarized (VH, VV) C-band backscatter values were examined for 30 burn events. For all events, a systematic backscatter decrease from pre-fire to post-fire conditions was observed, with mean backscatter decreases of 1.61 dB and 0.99 dB for VH and VV, respectively. A total of 90% and 75% of the burn events showed a decrease in VH and VV backscatter greater than 0.43 dB, the overall absolute radiometric of Sentinel-1A products. The VH data were, overall, 1.7 times more sensitive to surface fire effects than the VV data. C-band data are likely sensitive to a reduction in grass biomass typical of surface fires, as well as in grass/soil moisture levels. Early season fires had higher backscatter decreases due to greater early season moisture conditions. For region with more than 30% woody cover, the effect of fire on the C-band backscatter was reduced. Denser woody communities tend to produce lower grass fuel load and less intense surface fires, and limit the penetration of C-band microwaves to the ground where most savannah fires and associated effects occur. This research provides evidence that C-band space-borne SAR is sensitive to the effects of surface-level fires in southern African savannahs. The unique availability of frequent and spatially detailed C-band data from the Sentinel-1 SAR constellation provide new opportunities for burned area mapping and systematic monitoring in savannahs systems, for instance, for fine-scale fire propagation studies.


2015 ◽  
Author(s):  
◽  
Daniel Godwin

Savannas are thought to be bistable with forests potentially occurring above [about]650 mm / yr of Mean Annual Precipitation (MAP) due to the limiting effects of fire on tree cover. This is predicated on two assumptions: 1) fires increasingly limit woody cover in more mesic (> 650 MAP) savannas and 2) increasing tree cover produces feedbacks that reduce fire intensity. These assumptions are investigated in a spatially explicit framework. We use Kruger National Park (KNP), South Africa as our study system, in part due to the wide range of frequency of fires, the large variation in natural communities and rainfall, and the large body of previous research for comparisons and modeling efforts. To investigate whether tree cover produces feedbacks on fire intensity, we measured fire behavior as a function of grass fuel load and woody cover in experimental burns within KNP. We found weak but positive relationships (not negative, as assumed) between woody cover and fire intensity, independent of grass fuel load, and no relationship between tree cover and grass fuel load. At a landscape scale, we modeled the factors predicted to drive fire severity in KNP. We observed that fireline intensity is a strong predictor of many estimations of fire severity in small fires, but across larger fires, rainfall and woody cover likewise can predict impacts on herbaceous consumption and woody cover, respectively. Lastly, to investigate whether trees escape fire less often in more mesic savannas, we used a stochastic model parameterized with real data. After a review of published growth rates, we modeled fire escape probability using mean annual precipitation, fire frequency, and fireline intensity values across KNP. When accounting for species turnover across rainfall gradients, we found a nearly flat relationship between the probability of individuals escaping fire and rainfall. Our research challenges two key assumptions for fire-mediated bistability of mesic savannas.


Author(s):  
Kathleen Doyle ◽  
Dennis Knight

In the early 1970's, the growing awareness of the potential ecological impacts of fire suppression and the threat of more intensive fires due to fuel accumulation in fire-suppressed forests prompted the National Park Service to allow some fires to burn (Grand Teton National Park 1974). One of the first "prescribed natural fires" in a western National Park was the Waterfalls Canyon Fire (WCF) in Grand Teton National Park (GTNP). It was ignited by lightning in July 1974. Amid much public controversy (Anonymous 1974), the fire burned 1414 ha before it was extinguished by snow in December. In the following year, GTNP biologists established permanent plots within and adjacent to the WCF in forests dominated by subalpine fir, Engelmann spruce, and lodgepole pine, and which varied in fire severity and time since fire. The goal of the study was to document the effect of the 1974 fire by monitoring long-term changes in vegetation, breeding birds, and small mammals (Barmore et al. 1976). Data were collected from four study areas in 1975, 1976, 1977, and 1983 under the direction of William Barmore. In 1991 and 1992 we resampled the permanently-marked vegetation plots and breeding bird transects. Our objectives were to compile, analyze and interpret all of the data collected from the four study areas since 1975.


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