Assessing vegetation and avian community response to juniper reduction treatments in Southwest Montana
The Southwest Montana Sagebrush Partnership (SMSP) team, including land managers, landowners, and scientists, is implementing conifer removal projects encompassing over 55,000 acres of private, state, and federal lands throughout the region. To date, little place-based information exists regarding likely vegetation and bird responses to such treatments in Southwestern Montana. To address this knowledge gap, USGS scientists from the Fort Collins Science Center are partnering with the U.S. Bureau of Land Management (BLM), researchers at the University of Montana Bird Ecology Lab (UMBEL), and SMSP to analyze vegetation and avian count data collected between 2014–2022.
Background

The Southwest Montana Sagebrush Partnership (SMSP) team, including land managers, landowners, and scientists, is implementing conifer removal projects throughout the region encompassing over 55,000 acres of private, state, and federal lands. Managers implementing these conifer removal treatments need to know how ecosystems will respond to these treatments. For instance, prior studies suggest conifer removal may benefit understory vegetation by increasing soil moisture availability, ultimately increasing forbs and grasses (Bates and others 2000); however, these results are not ubiquitous across studies. Additionally, managers are uncertain regarding the longevity and efficacy of treatments and if there are differences in bird and vegetation responses between mechanical removal and prescribed fire treatments.
Management actions that influence vegetation are also likely to influence wildlife. Prior research suggests conifer removal may alter songbird occupancy (Magee and others 2019) and relative abundance (Holmes and others 2017). Songbird species associated with shrubland and sagebrush habitat generally increase and woodland-associated species decrease with conifer removal. However, there is little experimental evidence of the effects of conifer removal on songbird population density. Additionally, researchers have suggested that model inference regarding songbird response to treatments may lack transferability across space (Johnson and Sadoti 2019), indicating that place-based studies, where conifer removal is ongoing, is needed to inform local management.
Information regarding population-level responses of wildlife is even more important given recent research, funded in part by the BLM, indicating some woodland-associated songbird species are declining and their densities are likely to be negatively influenced by conifer removal (Van Lanen and others 2023a;b). As a result, managers implementing conifer removal can benefit from detailed knowledge regarding how conifer removal influences wildlife communities. This information can inform environmental impact assessments and management strategies aimed at recovering sagebrush-associated species while balancing population-level outcomes across the sagebrush and coniferous woodland ecosystems.
Project Objectives
This ongoing project will assess bird and vegetation responses to mechanical and prescribed fire conifer reduction treatments in southwestern Montana. This project is building upon preliminary analyses conducted by the UMBEL by leveraging baseline Integrated Monitoring in Bird Conservation Regions (IMBCR) avian point count data, incorporating weather and climate variables, and evaluating system response over time (that is, years since treatment). Incorporating these elements into the analyses provides the following benefits: (1) includes a larger number of avian species than was previously possible, (2) provides greater precision associated with treatment effects on the avian community, and (3) accounts for variation in weather, which preliminary analyses suggested may influence vegetation and avian responses.
Approach
USGS researchers are working closely with Anna Noson (UMBEL Research Director) and Katie Benzel (BLM Dillon Field Office Biologist) to identify management objectives and key management uncertainties. We are leveraging background IMBCR bird count data within Bird Conservation Region 10 (Northern Rockies) from the Bird Conservancy of the Rockies to supplement the UMBEL data. In addition, we are summarizing remotely sensed vegetation and climate data (such as LandFire, Rangeland Condition Monitoring Assessment and Projection, MODIS, and Daymet) to supplement ground-based data for inclusion in modeling efforts.
Using this data, we are modeling vegetation changes as a function of time since conifer removal treatments occurred. Our vegetation modeling effort accounts for site-specific differences and weather variation. We are also modeling avian density as a function of time since conifer removal treatments. Our avian density estimation accounts for imperfect detection and availability of individuals, random variation in sites, broad-scale avian population trends, and spatial scales of environmental influence for each species.
Project Partners
We are working with the University of Montana Bird Ecology Lab, the BLM-Montana Dillion Field Office, and Southwest Montana Sagebrush Partnership.
Shrubland Alpine & Grassland Ecology (SAGE) Wildlife Research Group
Modeling Songbird Density-Habitat Relationships to Predict Population Responses to Environmental Change Within Pinyon-juniper and Sagebrush Ecosystems
The Southwest Montana Sagebrush Partnership (SMSP) team, including land managers, landowners, and scientists, is implementing conifer removal projects encompassing over 55,000 acres of private, state, and federal lands throughout the region. To date, little place-based information exists regarding likely vegetation and bird responses to such treatments in Southwestern Montana. To address this knowledge gap, USGS scientists from the Fort Collins Science Center are partnering with the U.S. Bureau of Land Management (BLM), researchers at the University of Montana Bird Ecology Lab (UMBEL), and SMSP to analyze vegetation and avian count data collected between 2014–2022.
Background

The Southwest Montana Sagebrush Partnership (SMSP) team, including land managers, landowners, and scientists, is implementing conifer removal projects throughout the region encompassing over 55,000 acres of private, state, and federal lands. Managers implementing these conifer removal treatments need to know how ecosystems will respond to these treatments. For instance, prior studies suggest conifer removal may benefit understory vegetation by increasing soil moisture availability, ultimately increasing forbs and grasses (Bates and others 2000); however, these results are not ubiquitous across studies. Additionally, managers are uncertain regarding the longevity and efficacy of treatments and if there are differences in bird and vegetation responses between mechanical removal and prescribed fire treatments.
Management actions that influence vegetation are also likely to influence wildlife. Prior research suggests conifer removal may alter songbird occupancy (Magee and others 2019) and relative abundance (Holmes and others 2017). Songbird species associated with shrubland and sagebrush habitat generally increase and woodland-associated species decrease with conifer removal. However, there is little experimental evidence of the effects of conifer removal on songbird population density. Additionally, researchers have suggested that model inference regarding songbird response to treatments may lack transferability across space (Johnson and Sadoti 2019), indicating that place-based studies, where conifer removal is ongoing, is needed to inform local management.
Information regarding population-level responses of wildlife is even more important given recent research, funded in part by the BLM, indicating some woodland-associated songbird species are declining and their densities are likely to be negatively influenced by conifer removal (Van Lanen and others 2023a;b). As a result, managers implementing conifer removal can benefit from detailed knowledge regarding how conifer removal influences wildlife communities. This information can inform environmental impact assessments and management strategies aimed at recovering sagebrush-associated species while balancing population-level outcomes across the sagebrush and coniferous woodland ecosystems.
Project Objectives
This ongoing project will assess bird and vegetation responses to mechanical and prescribed fire conifer reduction treatments in southwestern Montana. This project is building upon preliminary analyses conducted by the UMBEL by leveraging baseline Integrated Monitoring in Bird Conservation Regions (IMBCR) avian point count data, incorporating weather and climate variables, and evaluating system response over time (that is, years since treatment). Incorporating these elements into the analyses provides the following benefits: (1) includes a larger number of avian species than was previously possible, (2) provides greater precision associated with treatment effects on the avian community, and (3) accounts for variation in weather, which preliminary analyses suggested may influence vegetation and avian responses.
Approach
USGS researchers are working closely with Anna Noson (UMBEL Research Director) and Katie Benzel (BLM Dillon Field Office Biologist) to identify management objectives and key management uncertainties. We are leveraging background IMBCR bird count data within Bird Conservation Region 10 (Northern Rockies) from the Bird Conservancy of the Rockies to supplement the UMBEL data. In addition, we are summarizing remotely sensed vegetation and climate data (such as LandFire, Rangeland Condition Monitoring Assessment and Projection, MODIS, and Daymet) to supplement ground-based data for inclusion in modeling efforts.
Using this data, we are modeling vegetation changes as a function of time since conifer removal treatments occurred. Our vegetation modeling effort accounts for site-specific differences and weather variation. We are also modeling avian density as a function of time since conifer removal treatments. Our avian density estimation accounts for imperfect detection and availability of individuals, random variation in sites, broad-scale avian population trends, and spatial scales of environmental influence for each species.
Project Partners
We are working with the University of Montana Bird Ecology Lab, the BLM-Montana Dillion Field Office, and Southwest Montana Sagebrush Partnership.