Influence of Wildland Fire Along a Successional Gradient in Sagebrush Steppe and Western Juniper Woodlands

Strand, Eva K.; Bunting, Stephen C.; Keefe, Robert F.

doi:10.2111/rem-d-13-00051.1

Cited by 22 publications

(18 citation statements)

References 42 publications

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“…Estimates of burn severity across large spatial extents are usually achieved using the differenced Normalized Burn Ratio (dNBR; Key and Benson 2006) or relativized dNBR (RdNBR; Miller and Thode 2007), spectral indices applied to satellite sensor imagery. Spectral indices have been shown to correlate with the loss of biomass, duff consumption, and mortality of shrubs and trees induced immediately by fire, as well as with delayed mortality of trees within the first year post fire Lentile et al 2007;Lentile et al 2009;Strand et al 2013;Miller et al 2016;Weiner et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Does burn severity affect plant community diversity and composition in mixed conifer forests of the United States Intermountain West one decade post fire?

et al. 2019

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Background: Wildfire is an important ecological process in mixed conifer forests of the Intermountain West region of the USA. However, researchers and managers are concerned because climate warming has led to increased fire activity in recent decades. More area burned will result in larger land areas in early successional stages and will potentially limit tree establishment; therefore, evaluating long-term forest understory response to fire is important. We evaluate the impact of burn severity, overstory canopy cover, topography, and climate on understory plant community diversity and composition in seven wildfires, 9 to 12 years post fire, along a broad climate gradient from dry to moist mixed conifer forests in Idaho, Montana, and Washington, USA. Results: Climate was the most important driver for species diversity and composition, but a burn severity gradient was detectable in the species data one decade post fire. A strong overlap in species composition between burn severity levels was documented, but dispersion was lower for high burn severity sites, indicating that those sites are still recovering. Local species richness and diversity had a nonlinear relationship with the burn severity index dNBR, with a maximum at low to moderate burn severity; the relationship was stronger in moist climates. Functional trait analysis revealed higher grass and forb cover in high-severity burns, higher cover of tree seedlings, residual and off-site colonizers in burned areas, and more shade-tolerant species in unburned areas. Of the 270 species recorded, 10% were introduced; however, only three were of noxious status and two were invasive annual grasses, generally occurring on dry sites. Conclusions: The understory plant community was not fundamentally altered by these fires and fire contributed to increased species diversity both locally and regionally, suggesting that low to moderate burn severity fire is a treatment that contributes to long-term maintenance of a diverse and productive understory. Individual species traits were significant drivers of understory species assemblages and, as future change in climate and fire regimes leads to shifts in species composition, anticipation of consequences will be important. Although invasive species occurred at low cover levels, noxious weeds and invasive annual grasses will continue to be management challenges, particularly in dry regions of mixed conifer forests.

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Section: Introductionmentioning

confidence: 99%

Does burn severity affect plant community diversity and composition in mixed conifer forests of the United States Intermountain West one decade post fire?

et al. 2019

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“…The conditional parameters used to model post-fire land cover composition in the decision model include broad assumptions, yet these parameters may be modified to simulate return to more ecologically complex land cover types. For example, sagebrush return in restored burned pinyonjuniper habitats may not occur, especially if disturbance thresholds associated with transitions from Phase 2 to Phase 3 woodlands have been surpassed , Strand et al 2013. Factors such as restoration method efficacy , seed source (Eiswerth et al 2009), and site evaluation of disturbance severity (e.g., perennial grass mortality; Miller et al 2008, Condon et al 2011 can also be incorporated into the conditional parameters provided they are spatially explicit.…”

Section: June 2018mentioning

confidence: 99%

“…Moreover, higher loadings of coarse woody fuels resulting from pinyon–juniper expansion can lead to more severe wildfires that also burn underlying or adjacent fire‐intolerant sagebrush (Strand et al. ). Following these high severity wildfires, invasive annual grasses that primarily include cheatgrass ( Bromus tectorum ) can form homogeneous and competitively dominant stands (Miller et al.…”

Section: Introductionmentioning

confidence: 99%

“…Dominance of sagebrush and perennial grasses, which contribute strongly to sagebrush ecosystem resilience to disturbance and resistance to invasion (hereafter RR; Chambers et al 2014a), declines concomitantly as pinyon-juniper canopy increases . Moreover, higher loadings of coarse woody fuels resulting from pinyon-juniper expansion can lead to more severe wildfires that also burn underlying or adjacent fire-intolerant sagebrush (Strand et al 2013). Following these high severity wildfires, invasive annual grasses that primarily include cheatgrass (Bromus tectorum) can form homogeneous and competitively dominant stands , 2011, Condon et al 2011, especially at lower elevations with warmer and drier climates.…”

Section: Introductionmentioning

confidence: 99%

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A conservation planning tool for Greater Sage‐grouse using indices of species distribution, resilience, and resistance

Ricca

Coates

Gustafson

et al. 2018

Ecological Applications

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Managers require quantitative yet tractable tools that identify areas for restoration yielding effective benefits for targeted wildlife species and the ecosystems they inhabit. As a contemporary example of high national significance for conservation, the persistence of Greater Sage-grouse (Centrocercus urophasianus) in the Great Basin is compromised by strongly interacting stressors of conifer expansion, annual grass invasion, and more frequent wildfires occurring in sagebrush ecosystems. Associated restoration treatments to a sagebrush-dominated state are often costly and may yield relatively little ecological benefit to sage-grouse if implemented without estimating how Sage-grouse may respond to treatments, or do not consider underlying processes influencing sagebrush ecosystem resilience to disturbance and resistance to invasive species. Here, we describe example applications of a spatially explicit conservation planning tool (CPT) to inform prioritization of: (1) removal of conifers (i.e., pinyon-juniper); and (2) wildfire restoration aimed at improving habitat conditions for the Bi-State Distinct Population Segment of Sage-grouse along the California-Nevada state line. The CPT measures ecological benefits to sage-grouse for a given management action through a composite index comprised of resource selection functions and estimates of abundance and space use. For pinyon-juniper removal, we simulated changes in land-cover composition following the removal of sparse trees with intact understories, and ranked treatments on the basis of changes in ecological benefits per dollar-unit of cost. For wildfire restoration, we formulated a conditional model to simulate scenarios for land cover changes (e.g., sagebrush to annual grass) given estimated fire severity and underlying ecosystem processes influencing resilience to disturbance and resistance to invasion by annual grasses. For both applications, we compared CPT rankings to land cover changes along with sagebrush resistance and resilience metrics. Model results demonstrated how the CPT can be an important step in identifying management projects that yield the highest quantifiable benefit to Sage-grouse while avoiding costly misallocation of resources, and highlight the importance of considering changes in sage-grouse ecological response and factors influencing sagebrush ecosystem resilience to disturbance and resistance to invasion. This unique framework can be adopted to help inform other management questions aimed at improving habitat for other species across sagebrush and other ecosystems.

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“…The expansion of juniper woodlands has also influenced the continuity and availability of wildland fuels (Miller et al 2013, Young et al 2015 and increased accumulation of litter and duff resulting from juniper leaf-fall (Weiner et al 2016). A fuel bed characterized by sparse vegetation, down woody debris, litter, and duff significantly increases fire return interval, but when fires do occur, they tend to be more severe (Miller et al 2013, Strand et al 2013. For clarity, fuel is defined as the live and dead biomass that can contribute to the spread, intensity, and severity of a fire (Rothermel 1983).…”

Section: Introductionmentioning

confidence: 99%

Fuel bed response to vegetation treatments in juniper-invaded sagebrush steppe

2018

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Background: Expansion of juniper (Juniperus spp. L.) and pinyon (Pinus spp. L.) into sagebrush steppe habitats has been occurring for over a century across western United States. Vegetation and fuel treatments, with the goal of increasing landscape diversity and herbaceous productivity, and reducing woody fuels are commonly implemented to mitigate effects of woodland encroachment in sagebrush ecosystems. This study was conducted in conjunction with the Sagebrush Steppe Treatment Evaluation Project (SageSTEP) and was designed to determine the impact of vegetation treatments on fuel variables two years post treatment in sagebrush steppe with an expanding juniper or pinyon −juniper woodland component. Ten locations that characterize common sagebrush steppe sites with an expanding woodland component in the Intermountain West were chosen for analysis. These woodland sites, covering a gradient of juniper development phases, were treated with mechanical (cut and leave) and prescribed fire treatments. Results: Two years post treatment, prescribed fire increased herbaceous biomass and reduced shrub biomass and down woody debris, but was not as effective in woodlands with higher juniper densities. Mechanical treatments increased herbaceous biomass and were effective in preserving the shrub biomass but increased down woody debris, which could lead to severe fire effects in the future. Conclusions: We conclude that both prescribed fire and mechanical treatments are important management tools for maintenance and restoration of sagebrush steppe in areas that support juniper woodland expansion, but the differences in effects on shrub biomass and woody debris must be considered. A combination of the two treatments could lead to desirable effects in many areas.

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Influence of Wildland Fire Along a Successional Gradient in Sagebrush Steppe and Western Juniper Woodlands

Cited by 22 publications

References 42 publications

Does burn severity affect plant community diversity and composition in mixed conifer forests of the United States Intermountain West one decade post fire?

Does burn severity affect plant community diversity and composition in mixed conifer forests of the United States Intermountain West one decade post fire?

A conservation planning tool for Greater Sage‐grouse using indices of species distribution, resilience, and resistance

Fuel bed response to vegetation treatments in juniper-invaded sagebrush steppe

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