Project: Assessing the proliferation, connectivity, and consequences of invasive fine fuels

Project

Assessing the proliferation, connectivity, and consequences of invasive fine fuels

March 2020 - May 2024

Personnel

Erin Buchholtz, Co-Principal Investigator

Participating Agencies

Invasive annual grasses are a growing threat to ecosystems in the western United States. They outcompete native species, influence wildlife habitat, and provide flammable fuels that intensify the wildfire regime. Landscape disturbances and management activities may lead to further spread of invasive annual grasses, and so it is important to characterize the proliferation, connectivity, and consequences of invasive grasses. Moreover, these grasses could impact habitats for species of interest such as the sage grouse. The project is a collaboration of researchers including the USGS FORT Science Center, USGS SC CFWRU, USGS PIERC, the Bureau of Land Management, and Colorado State University, the USGS Forest and Rangeland Ecosystem Science Center and State and Federal natural resource managers in the Pacific Northwest. This project can help develop strategies for managing annual invasive grasses, identifying characteristics and areas to target for appropriate management actions given the patterns and consequences of invasion.

Research Publications

Research Publications	Publication Date
Sofaer, HR, CS Jarnevich, EK Buchholtz, BS Cade, JT Abatzoglou, CL Aldridge, PJ Comer, D Manier, LE Parker, and JA Heinrichs. 2022. Potential cheatgrass abundance within lightly invaded areas of the Great Basin. Landscape Ecology 37, 2607–2618. doi.org/10.1007/s10980-022-01487-9 \| Abstract \| Publisher Website	October 2022	<b>Context: </b>Anticipating where an invasive species could become abundant can help guide prevention and control efforts aimed at reducing invasion impacts. Information on potential abundance can be combined with information on the current status of an invasion to guide management towards currently uninvaded locations where the threat of invasion is high.<br><b>Objectives: </b>We aimed to support management by developing predictive maps of potential cover for cheatgrass (<i>Bromus tectorum</i>), a problematic invader that can transform plant communities. We integrated our predictions of potential abundance with mapped estimates of current cover to quantify invasion potential within lightly invaded areas.<br><b>Methods: </b>We used quantile regression to model cheatgrass abundance as a function of climate, weather, and disturbance, treating outputs as low to high invasion scenarios. We developed a species-specific set of covariates and validated model performance using spatially and temporally independent data.<br><b>Results: </b>Potential cheatgrass abundance was higher in areas that had burned, at low elevations, and when fall germination conditions were more favorable. Our results highlight the extensive areas across the Great Basin where cheatgrass abundance could increase to levels that can alter fire behavior and cause other ecological impacts.<br><b>Conclusions:</b> We predict potential cheatgrass abundance to quantify relative invasion risk. Our model results provide high and low scenarios of cheatgrass abundance to guide resource allocation and planning efforts across shrubland ecosystems of the Great Basin that remain relatively uninvaded. Combining information on an invasive species’ current and potential abundance can yield spatial predictions to guide resource allocation and management action.
Buchholtz, E.K., J. Kreitler, D. Shinneman, M. Crist, & J. Heinrichs (2023). Assessing large landscape patterns of potential fire connectivity using circuit methods. Landscape Ecology. https://doi.org/10.1007/s10980-022-01581-y. \| Abstract	April 2023	Minimizing negative impacts of wildfire is a major societal objective in fire-prone landscapes. Models of fire connectivity can aid in understanding and managing wildfires by analyzing potential fire spread and conductance patterns. We define ‘fire connectivity’ as the landscape’s capacity to facilitate fire transmission from one point on the landscape to another. Our objective was to develop an approach for modeling fire connectivity patterns representing potential fire spread and relative flow across a broad landscape extent, particularly in the management-relevant context of fuel breaks. We applied an omnidirectional circuit theory algorithm to model fire connectivity in the Great Basin of the western United States. We used predicted rates of fire spread to approximate conductance and calculated current densities to identify connections among areas with high spread rates. We compared existing and planned fuel breaks with fire connectivity patterns. Fire connectivity and relative flow outputs were characterized by spatial heterogeneity in the landscape’s capacity to transmit fire. We found that existing fuel break networks were denser in areas with relatively diffuse and impeded flow patterns, rather than in locations with channelized flow. This approach could be paired with traditional fire behavior and risk analyses to better understand wildfire spread as well as direct strategic placement of individual fuel breaks within larger networks to constrain fire spread. Thus, our findings may offer local- to landscape-level support for management actions that aim to disrupt fire spread and mitigate the costs of fire on the landscape.
Buchholtz, E.K., J. Heinrichs, & M. Crist (2023). Landscape and connectivity metrics as a spatial tool to support invasive annual grass management decisions. Biological Invasions. doi.org/10.1007/s10530-022-02945-w \| Abstract \| Publisher Website	January 2023	The spatial context of invasions is increasingly recognized as important for the success and efficiency of management actions. This information can be key for managing invasive grasses that threaten native ecosystems. While methods for quantifying invasive grass presence and abundance advance, few options have been explored in characterizing and comparing spatial patterns of extent and connectivity. We calculated landscape metrics and circuit-based centrality for invasive grasses using a weighted-average product (30m resolution) in the Great Basin, USA. We found variation among extent metrics (mean class and patch area, number of patches, largest patch index) and connectivity metrics (nearest neighbor, contiguity, aggregation index, centrality); most of the extent and connectivity metrics were not strongly correlated with dominant abundance class and so provided additional information at the sampled grid and local scales. We also illustrated how thresholding relevant metrics could be used to identify areas needing different management strategies, for example, where strategies could proactively protect uninvaded cores, disconnect fine fuel patches, or contain established invasions. The landscape metric approach can be applied across scales to spatially target patches locally, provide broader context within a single region, as well as to compare metrics and spatial variation in patterns among different regions.

Presentations

Presentations	Presentation Date
Roche, M., J. Saher, E.K. Buchholtz, M. Crist, D. Shinneman, C. Aldridge, B. Brussee, P. Coates, C. Roth, J. Heinrichs. 2022. A spatial synthesis of fuel breaks in the sagebrush biome in relation to wildfire, invasive annual grasses, and Greater Sage-Grouse. Western Agencies 33rd Sage & Columbian Sharp-tailed Grouse workshop. 15 - 18 August 2022. Logan, Utah.	August 2022
Roche, M., J. Saher, E.K. Buchholtz, M. Crist, D. Shinneman, C. Aldridge, B. Brussee, P. Coates, C. Roth, J. Heinrichs. 2022. A Spatial Data Synthesis of Fuel Breaks in the Sagebrush Biome in Relation to Wildfire, Invasive Annual Grasses, and Sagebrush Obligate Wildlife. Oral presentation, North American Congress for Conservation Biology. 17 - 21 July 2022. Reno, NV.	July 2022
Kreitler, J., E.K. Buchholtz, M. Crist, J. Heinrichs, & D. Shinneman. A return on investment approach for evaluating fuel break priorities. International Association for Landscape Ecology - North America Annual Meeting, 11 - 14 April 2022.	April 2022
Heinrichs, J, E Buchholtz, H Sofaer, C Jarnevich, M Roche, C Aldridge, & M Crist. 2022. Assessing the cover, connectivity, and future proliferation of invasive fine fuels. Oral presentation, North American Congress for Conservation Biology. 17 - 21 July 2022. Reno, NV.	July 2022
Buchholtz, E.K., J. Kreitler, D. Shinneman, M. Crist, & J. Heinrichs. Assessing large landscape patterns of potential fire connectivity using circuit methods. Presentation (virtual) Annual Meeting, Society for Rangeland Management, Boise, ID, 15-18 February 2023.	February 2023
Buchholtz, E.K., J. Heinrichs, M. Crist, & C. Aldridge. Quantifying connectivity of invasive annual grasses in the Great Basin, USA. Oral presentation, International Association for Landscape Ecology - North America annual conference, virtual. 12 - 15 April 2021.	April 2021

Data or Software Releases

Type	Citation	Publication Date
Data Release	Buchholtz, E.K. and Kreitler, J.R., 2023, Circuit-based potential fire connectivity and relative flow patterns in the Great Basin, United States, 270 meters: U.S. Geological Survey data release, https://doi.org/10.5066/P9EA3E00.	April 2023
Data Release	Buchholtz, E.K. & J. Heinrichs. 2022. Landscape and connectivity metrics based on invasive annual grass cover from 2016-2018 summarized at 15 kilometer grid cells in the Great Basin, USA: U.S. Geological Survey data release. ScienceBase. https://doi.org/10.5066/P9B4H00Q.	October 2022

Cooperative Fish and Wildlife Research Units Program: Education, Research and Technical Assistance for Managing Our Natural Resources

Project

Assessing the proliferation, connectivity, and consequences of invasive fine fuels

March 2020 - May 2024

Personnel

Participating Agencies

Cooperative Fish and Wildlife Research Units Program:
Education, Research and Technical Assistance for Managing Our Natural Resources