Research and Publications
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Ventenata and medusahead are winter annuals that emerge in late fall, winter, and spring. These grasses mature early in the summer providing fine fuels for wildfires.Ventenata and medusahead are frequently found together where conditions allow. These invasive annual grasses increase wildfire danger in shrublands and woodlands of the American West.
- Fine, highly flammable fuel loads facilitate larger and more frequent fires.
- Relatively high silica content make these grasses less palatable for grazing (unlike cheatgrass which is palatable in its green phase), and creates a build-up of litter on the soil surface.
- These species can spread throughout areas that once acted as natural fire breaks.
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Co-varying disturbance and environmental gradients can shape vegetation dynamics and increase the diversity of plant communities and their features. Pinyon–juniper woodlands are widespread in semi-arid climates of western North America, encompassing extensive environmental gradients, and a knowledge gap is how the diversity in features of these communities changes across co-varying gradients in fire history and soil. In pinyon–juniper communities spanning soil parent materials (basalt, limestone) and recent fire histories (0–4 prescribed fires or managed wildfires and 5–43 years since fire) in Grand Canyon-Parashant National Monument (Arizona, USA), we examined variation at 25 sites in three categories of plant community features including fuels, tree structure, and understory vegetation. Based on ordinations, canonical correlation analysis, and permutation tests, plant community features varied primarily with the number of fires, soil coarseness and chemistry, and additionally with tree structure for understory vegetation. Fire and soil variables accounted for 33% of the variance in fuels and tree structure, and together with tree structure, 56% of the variance in understories. The cover of the non-native annual Bromus tectorum was higher where fires had occurred more recently. In turn, B. tectorum was positively associated with the percentage of dead trees and negatively associated with native forb species richness. Based on a dendroecological analysis of 127 Pinus monophylla and Juniperus osteosperma trees, only 18% of trees presently around our study sites originated before the 1870s (Euro-American settlement) and <2% originated before the 1820s. Increasing contemporary fire activity facilitated by the National Park Service since the 1980s corresponded with increasing tree mortality and open-structured stands, apparently more closely resembling pre-settlement conditions. Using physical geography, such as soil parent material, as a landscape template shows promise for (i) incorporating diversity in long-term community change serving as a baseline for vegetation management, (ii) customizing applying treatments to unique conditions on different soil types, and (iii) benchmarking monitoring metrics of vegetation management effectiveness to levels scaled to biophysical variation across the landscape.
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We leveraged work identifying sagebrush areas suitable for woody fuel treatments based on resilience to disturbance and resistance to annual grass invasion (R&R) and areas of sagebrush mapped as high conservation value. We used wildfire simulation modeling to estimate annual wildfire exposure (area burned), and identify areas where fire is transmitted to locations of high conservation value that are low R&R. We then optimized treatment location with the ForSys spatial planning system to prioritize treatment of wildfire exposure where treatments are ecologically suitable and explored how operational restrictions (e.g., distance to roads) limited the capacity to treat exposure. Overall, woody fuel treatments could be realistically implemented in only 7.6 % (2.5 million ha) of sagebrush dominated areas. We found that 24 % of the wildfire exposure across all sagebrush associations occurred where fuel treatments were ecologically suitable, but consideration of operational constraints reduced treatable exposure to 9 %. However, there was double the opportunity to reduce transmitted exposure to areas of high conservation value in the operational scenario despite restrictions. Leveraging treatment suitability and sagebrush conservation to strategically design implementable project treatment can help direct limited resources where they are likely to have the greatest ecological and risk reduction benefit.
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We created a regional-scale chronosequence of areas that burned only once from 1984 to 2017 using Landsat-derived burned area products, and collected species composition data across a gradient of 4–32 years since fire. We used linear mixed models to look for evidence of native plant recovery, and used indirect gradient analysis and joint species distribution models to examine the response of species occurrence to a) fire occurrence and timing and pre- and post-fire climate; and b) topography, grazing, and annual grass dominance.
Native diversity and perennial herbaceous cover were unrelated to time since fire and negatively associated with annual grass cover. The occurrence of a single fire had mostly negative associations with native species and mostly positive associations with non-native species. Grazing intensity did not affect the dominant post-fire annual grass, but non-native annual forbs sorted along a gradient towards two groups based on grazing intensity, annual grass cover, and topography.
Annual grass competition will likely maintain the post-fire invasive-dominated plant community even if management interventions successfully stop the grass-fire cycle.
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We showed that climate warming in southwest drylands has been associated with concurrent changes in vegetation and fuels and decreases in resistance and resilience. We provide an approach that allows managers to quantify the ongoing changes at management appropriate scales. We suggest climate smart management strategies to help direct ecosystems into conditions that can decrease fire risk, increase resistance to plant invasions, and reduce vulnerability to climate change.
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Exotic annual grasses and forbs were each reduced by herbicides and by seeding perennial grasses. The combination of herbicide and seeding reduced annuals and led to the largest increases in perennials. Although these outcomes support the intended effects of the treatments, there was high variability in outcomes among studies. Combined use of pre-emergent herbicides and seeding can increase the success of restoration interventions that are aimed at reducing the invasion of exotic annual grasses and increasing perennials after fire in sagebrush steppe. Our analysis revealed, however, that the available literature was not suited to answering more specific questions, in spite of the massive amount of post-fire herbicide and seedings that have been applied in burned sagebrush steppe. Specifically, there were too few topically relevant studies with adequate scientific reporting to properly evaluate differences among specific treatment methodologies, including specific herbicides, that affect restoration success.
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We applied indaziflam in fall 2019 to replicate plots within two sagebrush-steppe sites in the Northern Great Basin, USA: 1) a relatively intact, uninvaded, unburned “core” site and 2) a partially invaded site that burned in the 2015 Soda Wildfire. Vegetation cover, density, and growth responses of native perennials were measured annually to 2024. We asked whether our treatments “defended” and “grew” core sagebrush areas. EAG cover remained <15% in indaziflam-treated plots while increasing to >30% in control plots by the fifth year after treatment at the unburned site but did not differ with treatment at the burned site. Native perennial grasses, forbs, and big sagebrush cover and growth did not differ with indaziflam treatment at either site. Moss cover was temporarily lower in indaziflam-treated plots at the unburned site, and cover of a native annual forb was significantly lower in indaziflam-treated plots throughout the study across both sites. Despite posttreatment drought and apparent patchiness in treatment implementation, our treatments “defended the core” by preventing crossing of the 20% EAG invasion threshold in the unburned site but not did not “grow the core.” Our results provide an example of a case in which proactive protection may be easier to accomplish than reactive restoration. Herbicide treatment effects may be sensitive to weather and application details. Implementation monitoring could help explain variability and improve success.
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The Create a Cultural Burn Pathway workbook, released by the First Nations Emergency Services Society (FNESS) and the Indigenous Leadership Initiative (ILI), aims to help Indigenous Nations create cultural burn programs that reduce wildfire risk and revitalize a core part of our relationship with the land.
Indigenous Nations bring a range of current experience with cultural fire. To meet Nations where they are, FNESS and ILI launched a multi-year community-based research project, involving over 50 Elders and knowledge holders, numerous gatherings and workshops, extensive peer reviews, and multiple edits to the workbook to reflect all the input.
The result is a workbook containing seven worksheets that walk communities through the development of a strong cultural fire program—no matter what stage they are in.
Cultural fire is culture and location specific. So instead of a prescriptive approach, each worksheet poses a set of questions and prompts that can be answered collectively.
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Short-term fire risk reduction and long-term resilience objectives can be complementary within a landscape, but ecosystem resilience is not a guaranteed co-benefit when fire risk reduction is the primary objective. Rather, improving ecosystem resilience cannot be achieved quickly because many desired forest conditions require both deliberate strategic action to guide the location, character, and timing of management as a disturbance agent, as well as adequate time for landscape conditions to improve and resilience benefits to be realized.
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Fire is an ecosystem process managed in the contemporary western U.S. at great expense, but with mixed results— yet it is one that can be re-worked to positive effect by melding ancient burning practices with contemporary scientific findings.
The “natural infrastructure” elements of stone and wood are components of ecosystem processes whose contemporary application, when guided by ancient practices and recent research, can mitigate some of the negative effects of contemporary fire regimes.
The following fact sheet is a summary of our 2025 working paper which considers how scientific research and creative on-the-ground applications that merge ancient and contemporary approaches and techniques can improve both pre-event resilience, and post-event recovery outcomes.