Long-Term Effects of Fire on Vegetation Structure and Predicted Fire Behavior in Wyoming Big Sagebrush Ecosystems

Reis, Schyler Ainsworth; Ellsworth, Lisa M.; Kauffman, J. Boone; Wrobleski, David W.

doi:10.1007/s10021-018-0268-7

Cited by 8 publications

(8 citation statements)

References 24 publications

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“…Shrub and downed woody fuel remained present but was sparse throughout the 10 years after prescribed fire, while herbaceous fuel increased without increasing total fuel loads. This is consistent with two prescribed fire studies on similar sites, which showed large reductions in shrub cover following fire and slow recovery of the sagebrush canopy in the 17-18-year study periods (Reis et al, 2019;Wambolt & Payne, 1986). By contrast, both studies had large increases in perennial grass production immediately F I G U R E 5 Modeled mean reaction intensity (in kilowatts per square meter per minute) in control, control + imazapic, prescribed fire, prescribed fire + imazapic, mechanical treatment, mechanical + imazapic, tebuthiuron, and tebuthiuron + imazapic plots in SageSTEP plots across four curing scenarios (fully green, one-third cured, two-thirds cured, and fully cured) in SageSTEP plots across the Great Basin, USA, in Years 0, 1, 2, 3, 6, and 10 after treatment following burn treatments that persisted through the 17-18-year study periods, which can result in increased fire behavior metrics (Brown, 1982;Ellsworth et al, 2020).…”

Section: Discussionsupporting

confidence: 91%

Fuel reduction treatments reduce modeled fire intensity in the sagebrush steppe

et al. 2022

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Increased fire size and frequency coupled with annual grass invasion pose major challenges to sagebrush (Artemisia spp.) ecosystem conservation, which is currently focused on protecting sagebrush community composition and structure. A common strategy for mitigating potential fire is to use fuel treatments that alter the structure and amount of burnable material, thus reducing fire behavior and creating access points for fire suppression resources. While there is some recent information on the impacts of fuel treatments on ecological communities, we have little information on fuel treatment effectiveness at modifying fire behavior in sagebrush ecosystems. We present 10 years of data on fuel accumulation and the resultant modeled fire behavior in prescribed fire, mowed, herbicide (tebuthiuron or imazapic), and untreated control plots in the Sagebrush Treatment Evaluation Project (SageSTEP) network in the Great Basin, USA. Fuel data (i.e., aboveground burnable live and dead biomass) were collected in each treatment plot at Years 0 (pretreatment), 1, 2, 3, 6, and 10 posttreatment. We used the Fuel and Fire Tool fire behavior modeling program to test whether treatments impacted potential fire behavior. Prescribed fire initially removed 49% of the total fuel load and 75% of shrubs, and fuel loads remained reduced through Year 10. Mowing shifted fuels from the shrub canopy to the ground surface but did not change the total fuel amount. Prescribed fire and mowing increased herbaceous fuel by the second posttreatment year and that trend persisted through Year 10. Tebuthiuron treatments were ineffective at altering fuel loads. Imazapic suppressed herbaceous vegetation by 30% in Years 2 and 3 following treatment. The modified fuel beds in fire and mow treatments resulted in modeled flame lengths that were significantly lower than untreated control plots for the duration of the study, with shorter term reductions in reaction intensity and rate of spread. Understanding fuel treatment effectiveness will allow natural resource managers to evaluate trade‐offs between protecting wildlife habitat and reducing the potential for high‐intensity wildfire.

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Section: Discussionsupporting

confidence: 91%

Fuel reduction treatments reduce modeled fire intensity in the sagebrush steppe

et al. 2022

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“…Wyoming big sagebrush has limited means for immediately refilling these voids, due to a limited and short‐lived seed bank (Pekas & Schupp, 2013; Wijayratne & Pyke, 2012), episodic seed production, and an arid climate that often restricts germination and young plant growth (Booth et al, 2003; Perryman et al, 2001; Shriver et al, 2018). In contrast, fire can stimulate recovery and sometimes dominance of fire‐tolerant and resprouting shrubs (Miller et al, 2013; Pyke et al, 2010), such as green rabbitbrush ( Ericameria teretifolia ) (Blaisdell, 1953; Rhodes et al, 2010; Young & Evans, 1974), although we found no increase in E. teretifolia (Chambers et al, 2021; Reis et al, 2019) in our study.…”

Section: Discussioncontrasting

confidence: 58%

Ten‐year ecological responses to fuel treatments within semiarid Wyoming big sagebrush ecosystems

et al. 2022

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Sagebrush ecosystems of western North America are threatened by invasive annual grasses and wildfires that can remove fire‐intolerant shrubs for decades. Fuel reduction treatments are used ostensibly to aid in fire suppression, conserve wildlife habitat, and restore historical fire regimes, but long‐term ecological impacts of these treatments are not clear. In 2006, we initiated fuel reduction treatments (prescribed fire, mowing, and herbicide applications [tebuthiuron and imazapic]) in six Artemisia tridentata ssp. wyomingensis communities. We evaluated long‐term effects of these fuel treatments on: (1) magnitude and longevity of fuel reduction; (2) Greater Sage‐grouse habitat characteristics; and (3) ecological resilience and resistance to invasive annual grasses. Responses were analyzed using repeated‐measures linear mixed models. Response variables included plant biomass, cover, density and height, distances between perennial plants, and exposed soil cover. Prescribed fire produced the greatest reduction in woody fuel over time. Mowing initially reduced woody biomass, which recovered by year 10. Tebuthiuron did not significantly reduce woody biomass compared to controls. All woody fuel treatments reduced sagebrush cover to below 15% (recommended minimum for Greater Sage‐grouse habitat), but only prescribed fire reduced cover to below controls. Median mowed sagebrush height remained above the recommended 30 cm. Cheatgrass (Bromus tectorum) cover increased to above the recommended maximum of 10% across all treatments and controls. Ecological resilience to woody fuel treatments was lowest with fire and greatest with mowing. Low resilience over the 10 posttreatment years was identified by: (1) poor perennial plant recovery posttreatment with sustained reductions in cover and density of some perennial plant species; (2) sustained reductions in lichen and moss cover; and (3) increases in cheatgrass cover. Although 10 years is insufficient to conclusively describe final ecological responses to fuel treatments, mowing woody fuels has the greatest potential to reduce woody fuel, minimize shrub mortality and soil disturbance, maintain lichens and mosses, and minimize long‐term negative impacts on Greater Sage‐grouse habitat. However, maintaining ecological resilience and resistance to invasion may be threatened by increases in cheatgrass cover, which are occurring regionally.

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“…3B ). This pattern of native species resilience following fire in ungrazed landscapes has been reported in bunchgrass prairies (Montana; Antos et al 1983 ), Wyoming big sagebrush (Oregon and Washington; Ellsworth et al 2016 ; Reis et al 2019 ; Ponzetti et al 2007 ), Mountain big sagebrush (California and Oregon, Ellsworth and Kauffman 2010 ; Ellsworth and Kauffman 2017 ), and Basin big sagebrush ecosystems (Oregon; Ellsworth et al 2020 ). Furthermore, many native grasses and forbs that are key species in springtime diets of greater sage-grouse ( Centrocercus urophasianus ) exhibit high rates of reproduction following fires (i.e., fire-enhanced flowering) and in the absence of livestock grazing and trampling (Wroblesky and Kauffman 2003 ).…”

Section: Cessation Of Livestock Grazing Increases Carbon Storagesupporting

confidence: 56%

Livestock Use on Public Lands in the Western USA Exacerbates Climate Change: Implications for Climate Change Mitigation and Adaptation

Kauffman

Beschta

Lacy³

et al. 2022

Environmental Management

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Public lands of the USA can play an important role in addressing the climate crisis. About 85% of public lands in the western USA are grazed by domestic livestock, and they influence climate change in three profound ways: (1) they are significant sources of greenhouse gases through enteric fermentation and manure deposition; (2) they defoliate native plants, trample vegetation and soils, and accelerate the spread of exotic species resulting in a shift in landscape function from carbon sinks to sources of greenhouse gases; and (3) they exacerbate the effects of climate change on ecosystems by creating warmer and drier conditions. On public lands one cow-calf pair grazing for one month (an “animal unit month” or “AUM”) produces 875 kg CO2e through enteric fermentation and manure deposition with a social carbon cost of nearly $36 per AUM. Over 14 million AUMs of cattle graze public lands of the western USA each year resulting in greenhouse gas emissions of 12.4 Tg CO2e year−1. The social costs of carbon are > $500 million year−1 or approximately 26 times greater than annual grazing fees collected by managing federal agencies. These emissions and social costs do not include the likely greater ecosystems costs from grazing impacts and associated livestock management activities that reduce biodiversity, carbon stocks and rates of carbon sequestration. Cessation of grazing would decrease greenhouse gas emissions, improve soil and water resources, and would enhance/sustain native species biodiversity thus representing an important and cost-effective adaptive approach to climate change.

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Long-Term Effects of Fire on Vegetation Structure and Predicted Fire Behavior in Wyoming Big Sagebrush Ecosystems

Cited by 8 publications

References 24 publications

Fuel reduction treatments reduce modeled fire intensity in the sagebrush steppe

Fuel reduction treatments reduce modeled fire intensity in the sagebrush steppe

Ten‐year ecological responses to fuel treatments within semiarid Wyoming big sagebrush ecosystems

Livestock Use on Public Lands in the Western USA Exacerbates Climate Change: Implications for Climate Change Mitigation and Adaptation

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