Search Results: %2525257Bsearch_term_string%2525257D
View article.
This study suggests that both prescribed fire and its mechanical surrogates are generally successful in meeting short-term fuel-reduction objectives in seasonally dry forests in the western and southern United States, making treated stands more resilient to high-intensity wildfire. Although mechanical treatments do not serve as complete surrogates for fire, their application can help mitigate costs and liability in some areas. Desired treatment effects on fire hazards are transient, which indicates that after fuel-reduction management starts, managers need to be persistent with repeated treatment.
View article
We propose an integrated fire management approach in which all management activities before, during, and after wildfire are synergistic and improve long-term ecosystem response to fire. Harney County Wildfire Collaborative is adapting the Potential Operational Delineations (PODs) framework to improve fire outcomes and promote values at risk in the Stinkingwater Mountains pilot project area. The PODs framework serves to promote a broader geographic strategy for addressing the underlying causes of frequent and severe wildfires in the sagebrush ecosystem.
Access brief.
Forest Service researchers Becky Kerns and Michelle Day conducted a long-term experiment in the Malheur National Forest, Oregon, to assess how season and time between prescribed burns affect understory plant communities in ponderosa pine forests. They found that some native plants persisted and recovered from fire but didn’t respond vigorously, while invasive species tended to spread. These findings may help forest managers design more effective prescribed-fire treatments and avoid unintended consequences.
View fact sheet.
This longer-term study essentially shows that native seed mixes do well in suppressing cheatgrass in the Great Basin, even when compared to familiar conventional mixes that include the highly competitive nonnative crested and Siberian wheatgrass. The conventional seed mixes lived up to their reputation and were effective at keeping cheatgrass cover below 2 percent, but the native seed mixes were not far behind, with cheatgrass cover of 3 percent to 6 percent–in contrast to unseeded control treatments where cheatgrass cover reached 9 percent to 15 percent. And using native seed mixes may not be cost-prohibitive anymore—the scientists found that the price of native species seed has come down over the years to be much closer to that of introduced mixes.
Read article.
This study assessed plant community succession following prescribed fire on ungrazed Wyoming big sagebrush steppe, eastern Oregon. Herbaceous yield, vegetation canopy cover and density were compared between treatments after fire (2003–18). Herbaceous yield in the Burn treatment was about double the control for most of the study period. Prior to fire, native perennials comprised 90–95% of herbaceous yield. After fire, native perennials represented 78% (range 67–93%) and exotic annuals 22% (range 7–33%) of total yield. Exotic annuals increased after fire and responded in two stages. In the first 8 years after fire, desert alyssum dominated the annual plant composition. In the last half of the study, cheatgrass co-dominated the annual component with alyssum. Sagebrush recovery was slow and we estimated sagebrush cover would return to pre-burn levels, at the earliest, in 115 years. Burning Wyoming big sagebrush steppe would be detrimental to sagebrush-obligate wildlife for an extended time period, because of lost cover and structure provided by sagebrush. The additional forage provided on burned areas may give livestock manager’s greater flexibility to rest or defer unburned habitat for wildlife species of critical concern.
View article.
This study asked whether success in restoration seedings of the foundational species big sagebrush was related to estimated water deficit in previously burned areas in the western United States. Standardized precipitation-evapotranspiration index (SPEI), a widely used drought index, was not predictive of whether sagebrush had reestablished. In contrast, wet-warm days elicited a critical drought threshold response, with successfully reestablished sites having experienced 7 more wet-warm days than unsuccessful sites during the first March following summer wildfire and restoration. Thus, seemingly small-scale and short-term changes in water availability and temperature can contribute to major ecosystem shifts, as many of these sites remained shrubless two decades later. These findings help clarify the definition of ecological drought for a foundational species and its imperiled semi-arid ecosystem. Drought is well known to affect the occurrence of wildfires, but drought in the year(s) after fire can determine whether fire causes long-lasting, negative impacts on ecosystems.
Access summary and report.
The primary objective of this study was to explore the application of a dynamic global vegetation model (DGVM), the Ecosystem Demography (EDv2.2), to understand vegetation dynamics and ecosystem productivity in varying climate and fire scenarios. Most vegetation models do not represent sagebrush’s physical and physiological functions. Thus, we developed a sagebrush plant functional type (PFT) to use in modeling. Associated with this, the researchers performed a series of analyses and evaluations of the sagebrush and in the context of scenarios under natural (undisturbed) and disturbed (fire) environments.
- Results indicate that a number of sagebrush parameters are most sensitive to how productive the plant is (in our model). These include specific leaf area (SLA), stomatal slope, fine root turnover rate, cuticular conductance, and maximum carboxylation rate. These findings allow future sagebrush modeling efforts to further refine these parameters in different environments.
- The researchers comparisons between model runs and field data from Reynold Creek Experimental Watershed (RCEW), show good agreement. Improvements are needed to refine the model with additional PFTs representative of a range of elevations in the Great Basin.
- The researchers fire scenario modeling suggested that fire substantially reduced shrub gross primary production (GPP) and it took several decades before it was restored to pre-fire conditions. Grass GPP, however, responded more quickly in post-fire conditions. While these processes are representative of field observations and other studies, additional PFTs and improvement in fire routines in the model will provide for a better prognosis of future ecosystem dynamics of the sagebrush-steppe.
View article.
Respondents were less confident in the accuracy of wind and precipitation forecasts than relative humidity or weather forecasts more generally. The influence of weather information on the decision depended on the framing used in the choice experiment; specifically, whether respondents were told the initial strategy had been to directly or indirectly attack the fire. Across conditions, fire managers generally preferred to indirectly attack the fire. Decisions about the tactics to apply going forward were more sensitive to time in season when the fire was occurring and wind and precipitation forecasts than to other attributes.
Read the study.
This study compared seeding and not seeding mountain big sagebrush after juniper control (partial cutting followed with burning) in fully developed juniper woodlands (i.e., sagebrush had been largely excluded) at five sites, 7 and 8 yr after seeding. Sagebrush cover averaged ~ 30% in sagebrush seeded plots compared with ~ 1% in unseeded plots 8 yr after seeding, thus suggesting that sagebrush recovery may be slow without seeding after juniper control. Total herbaceous vegetation, perennial grass, and annual forb cover was less where sagebrush was seeded. Thus, there is a trade-off with herbaceous vegetation with seeding sagebrush. Our results suggest that seeding sagebrush after juniper control can accelerate the recovery of sagebrush habitat characteristics, which is important for sagebrush-associated wildlife. We suggest land manager and restoration practitioners consider seeding sagebrush and possibly other shrubs after controlling encroaching trees where residual shrubs are lacking after control.
This study found that mulch did not influence understory plant diversity, species richness, or fractional ground cover. However, on mulched plots, tree seedlings grew taller faster, especially on north-facing aspects, and there was slightly more graminoid cover. Mulch did not affect overall tree seedling density, but there were fewer ponderosa pine (Pinus ponderosa Lawson & C. Lawson) and more Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) in mulched areas, especially on south-facing slopes.