Invasive Species
The US Geological Survey Land Management Research Program and the Great Basin Fire Science Exchange are teaming up again to bring you updates in sagebrush, fire, invasives, wildlife, and monitoring related research.
Each 90-minute webinar will be comprised of multiple manager-focused presentations.
Dates, topics, and registration:
6/10, 1:00 PDT/2:00 MDT – Greater sage-grouse, – Register
Pete Coates – Greater sage-grouse hierarchical population monitoring framework
Shawn O’Neil – Influence of future climate scenarios on habitat and population dynamics of greater sage-grouse
Greg Wann – GRSG habitat maps, trends, and thresholds
Sara Oyler-McCance – GRSG genetic synthesis
Shawna Zimmerman – Charaterizing the environmental drivers of range-wide gene flow
Shawna Zimmerman – Characterizing Greater sage-grouse climate driven maladaptation
6/11, 1:00 PDT/2:00 MDT – Wildlife, carbon, grazing, and fuel breaks – Register
Seren Bagcilar – Decadal effects of fuel treatments and annual grass invasion on sagebrush ecosystem carbon stocks
Jason Kreitler – UAS survey of sagebrush fuel breaks
Martin Holdrege – Livestock grazing for climate adaptation in drylands leads to tradeoffs between fire and vegetation condition
Will Janousek – Patterns and practical tools: Managing the interplay of habitat quality and temperature on mule deer demographics
Robert Arkle – Effects of fire and post-fire restoration seeding treatments on mammals in sagebrush steppe
Bill Davidson – Experiments to provide guidance on post-fire grazing resumption
6/15, 10:00 PDT/11:00 MDT – Invasive species – Register
Matthew Rigge – RCMAP near-real time exotic grass mapping
Julie Heinrichs – Assessing the proliferation, connectivity, and consequences of invasive fine fuels
Morgan Roche – Vectors of annual grass invasion
Cameron Aldridge – Synthesis of indaziflam outcomes for protecting sagebrush ecosystems
Bryan Tarbox – Increase connectivity within the SCD and assessing cheatgrass treatment efficacy
Matt Germino – Landscape-scale assessment of emerging techniques for controlling exotic annual grasses and longevity of herbicides
James Meldrum – Invasive annual grass economic assessment
6/16, 2:00 PDT/3:00 MDT – Monitoring – Register
Michelle Jeffries – Rangeland Monitoring Program, tech transfer tools from NORMP, and ROAM monitoring project
Stella Copeland – Variability in post-fire non-native perennial grass seeding outcomes
Matt Germino – Adapting digital geotech to work at the scale of management
Matthew Rigge – RCMAP vegetation trend summaries
6/17, 10:00 PDT/11:00 MDT – Fire – Register
Adam Noel – PJ treatments for minimizing climate and fire vulnerability
Cara Applestein – Predicting reburn risk to restoration investments
Seth Munson – Lessons from other ecosystems: TLS and remote sensing based multi-year fuel model and evaluation of past treatments
Jake Price – New, precision approaches for prioritizing fuel treatments
Matt Germino – Effectiveness of layering treatments in response to wildfire in sagebrush
View article.
Our study demonstrates that invasive annual grasses are rapidly spreading across the study area regardless of prescribed fire. Low severity prescribed fire may not exacerbate the invasion of some annual grasses in forested areas and sagebrush patches where the canopy cover is already open. However, burning in sagebrush patches may have negative effects on important non-forest ecosystems when burning results in the loss of fire-sensitive species. This information can help aid decision making and improve species-specific management and treatment effectiveness in dry forest landscapes.
View article.
Invasive annual grasses (IAG) continue to spread within the sagebrush biome of the western United States, degrading plant communities and wildlife habitat, decreasing forage for ranching livelihoods, and heightening wildre risk. Effective management of IAGs requires action and long-term strategic planning across the sage-brush biome, but the cumulative effects of IAG treatments over time and space are not well understood, espe-cially over broad extents dened for strategies like the Sagebrush Conservation Design. We developed a simulation model and sampling framework that allow local-scale actions to be ‘scaled up’ to evaluate large-scale regional and biome-wide management strategy outcomes. We worked with natural resource managers and ex-perts to co-develop a spatially explicit state-and-transition simulation model of IAG dynamics in sagebrush landscapes that can be used to evaluate alternative management strategies. We evaluated our framework by contrasting two baseline scenarios in terms of their long-term effects on the sagebrush biome. We show that focusing management efforts on moderate to high IAG cover was effective at reducing full conversion to IAGs but failed to prevent widespread establishment of IAGs in core sagebrush areas, exposing them to increased risk of wildre and wildlife habitat degradation. The results of our model help quantify the extent of the problem that IAGs pose to sagebrush ecosystems given current knowledge and management efforts. Our framework provides a platform to explore alternative management strategy outcomes and can help managers develop informed con-servation plans with realistic expectations for return on investment of resources committed to sagebrush landscapes.
View description and access tool.
Invasive annual grasses (IAG) pose one of the most significant and rapidly expanding threats to rangeland health across the western United States. These exotic grasses include cheatgrass, medusahead, and ventenata, and when they overtake rangelands, they alter fire regimes, reduce habitat quality, and diminish long-term productivity. Developing effective management strategies and treatment prescriptions requires an understanding of the degree of invasion in an ecological context, including site potential, competitive balance with perennial grasses and forbs, and overall productivity. The Invasion Severity Index (ISI) maps and web app provide a simple, interactive platform to help conservation planners and land managers prioritize and plan invasive annual grass treatments across the sagebrush biome. Using cutting-edge Rangeland Analysis Platform (RAP) 10-meter resolution data, ISI maps depict five invasion levels linked to specific management strategies and actions. The ISI assesses the severity of annual grass invasion relative to perennial forb and grass cover and bare ground, providing an ecologically grounded framework for prioritizing management and aligning treatment techniques with site resilience and recovery potential. Other reference layers and features allow users to understand landscape context, consider trends through time, visualize specific vegetative thresholds, and generate time series charts.
View article.
Both commercial and wild mixtures suppressed B. tectorum relative to control mesocosms without native plants. The commercial mixture produced more aboveground volume than wild mixtures in both seasons, but was less effective at suppressing B. tectorum, which accumulated 67% more biomass in commercial mesocosms than in wild ones. Commercial communities shrank following invasion. In contrast, several wild communities had near-complete B. tectorum suppression, despite smaller aboveground volume, and all wild communities increased in size in the second season. Highly competitive wild mixtures are promising for restoration and suggest a potential trade-off between rapid aboveground growth and invasion resistance. Commercially available native plants selected for agronomic traits like large size and high seed yield may lack characteristics desirable in invaded dryland restoration settings, such as weed suppression and low biomass production to reduce fuel for wildfires.
View article.
Models using both field collected and remotely sensed vegetation indices estimated increases in exotic annual grass cover over time following mowed fuel break installation, and higher exotic annual grass cover closer to mowed fuel breaks. These increases in exotic annual grass occurred within, at 500 m and at 1000 m from mowed fuel breaks. However, we found variable patterns of exotic annual grass after green strip fuel break installation depending on the data source. No increase in exotic annual grass was indicated by either analysis at distances greater than 500 m from green strip fuel breaks. However, our remotely sensed and field data analyses disagreed on the direction of the association of exotic annual grass cover and green strip fuel breaks. Although fuel breaks are an important tool in managing wildland fire, our analysis underscores the importance of planting fire-resistant vegetation, rather than mowing alone, to reduce invasion by annual grasses within and around fuel breaks in sagebrush ecosystems. In addition, site characteristics that hinder the proliferation of exotic annual grasses could be evaluated when installing fuel breaks to minimize unintended effects of exotic annual grass on surrounding sagebrush habitat.
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Many non-native invasive grass species increase wildfire activity and regenerate more quickly than native species. This invasive grass-fire cycle has severe negative consequences for ecosystems, creating a need to understand how different invasive grass species alter fuel characteristics and fire behavior, as well as effective treatments to control their abundance. To address these needs and increase fire and natural resource management preparedness, we performed a review and meta-analysis of recent (1985 – 2023) scientific literature. We focused on the Intermountain West, USA, where six dominant invasive grass species have already transformed ecosystems, including winter annuals – cheatgrass, medusahead, red brome, and Mediterranean grass; and summer perennials – buffelgrass and Lehmann’s lovegrass. Of the 204 selected articles, B. tectorum was the most well-studied species, treatment effectiveness was the most common study type, and more studies addressed fuel accumulation than fire characteristics. While initial reductions in B. tectorum following wildfire were followed by large increases, P. ciliare initially increased and then steadily declined, and other invasive grass species had no significant post-fire changes over time. Chemical treatments were more effective than other treatments for B. tectorum , P. ciliare , and Schismus spp. , though T. caput-medusae had a larger reduction with chemical treatments compared to the other species. In many cases, treatment effectiveness was enhanced when treatment types were combined or repeat treatments were conducted. Both B. tectorum and T. caput-medusae increased to pre-treatment conditions within 3 and 5 years, respectively, though there were no detectable trends for other species. Our results provide comprehensive comparisons of the effect of invasive grass species on fuel and fire characteristics, and much needed insight on effective strategies for reducing their impact to ecosystems.
View article.
The impacts of climate shifts on ecosystems dominated by long-lived perennials are likely most pronounced during community reassembly after disturbances such as fire and confounded by interactions between disturbances and plant community composition. A 30-year-experimental hydroclimate manipulation of multiple sagebrush steppe communities was completely consumed by a 2019 wildfire, providing an opportunity to evaluate effects of precipitation deficit on ecosystem recovery. Ambient precipitation was doubled for 23 years via irrigation in winter or summer in grassland or shrub–steppe communities until 2016. Plots that had received irrigation thus experienced drought for three years preceding and continuing after the fire. These landscapes are vulnerable to invasion by exotic annuals such as Bromus tectorum L. (cheatgrass) that promote wildfire occurrence, which favors even greater invasion levels. Thus, we asked whether patterns of invasion after the compound disturbance of drought and fire related to the long-term pre-fire climate and plant community structure. Established theory led to the prediction that plant communities developed under wetter climates would have greater resistance to invasion. The most resistant plots were the most arid (that is, never irrigated control plots with no drought) which had the least pre-fire canopy cover of shrubs and nitrogen-fixing forbs and greater proportional cover of perennial bunchgrasses. Plots that developed under winter irrigation had greater cover of shrubs and N-fixing forbs, corresponding to pulses of plant available soil nitrogen that were 8.2-fold greater than pre-fire levels, compared to a 0.20-fold post-fire reduction in soil nitrogen observed in the ambient plots. Nitrogen pulses and invasion were most evident in the inter-canopy bare-soil patches (‘interspaces’) and were least evident where perennial grasses were most abundant. Long-term hydroclimate altered pre-fire plant community composition in ways that affected post-fire resistance to invasion such that the combined effects of fire and water deficit led to greater than expected invasion in wetter regions that are conventionally considered resistant to invasion and resilient to wildfire.
Workshop webpage.
This two-day workshop is designed to take an in depth look at how you can apply a set of principles and tools to strategically manage IAGs in Eastern Idaho. Our target audience includes both land managers and producers. Whether you are from the area or from the greater western US, this workshop is designed to help participants gain knowledge about how to best tackle IAGs through conversations about various management practices depending on invasion severity and recovery potential. Management goals can vary depending on how success is defined.
View article.
Wildfire induced large declines in the live overstory biomass for control (47%) and prescribed fire plots (32%) though remotely sensed burn severity was lower in treated plots relative to the control. Downed woody fuels and duff were consumed equivalently in both control and treated plots, ranging from 24 to 99% consumption. Grass loading increased 78-fold in control plots and 22-fold in prescribed fire plots after wildfire, largely driven by invasive cheatgrass, which comprised 79% to 99% of grass cover. However, overstory canopy cover was negatively correlated with cheatgrass loadings (R2 = 0.81) and cover (R2 = 0.84).