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The sagebrush biome is a dryland region in the western United States experiencing rapid transformations to novel ecological states. Threat‐based approaches for managing anthropogenic and ecosystem threats have recently become prominent,... more
The sagebrush biome is a dryland region in the western United States experiencing rapid transformations to novel ecological states. Threat‐based approaches for managing anthropogenic and ecosystem threats have recently become prominent, but successfully mitigating threats depends on the ecological resilience of ecosystems. We used a spatially explicit approach for prioritizing management actions that combined a threat‐based model with models of resilience to disturbance and resistance to annual grass invasion. The threat‐based model assessed geographic patterns in sagebrush ecological integrity (SEI) to identify core sagebrush, growth opportunity, and other rangeland areas. The resilience and resistance model identified ecologically relevant climate and soil water availability indicators from process‐based ecohydrological models. The SEI areas and resilience and resistance indicators were consistent—the resilience and resistance indicators showed generally positive relationships wit...
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The spatial patterns and context of invasions are increasingly recognized as important for successful and efficient management actions. Beyond mapping occurrence or percent cover in pixels, spatial summary information that describes the... more
The spatial patterns and context of invasions are increasingly recognized as important for successful and efficient management actions. Beyond mapping occurrence or percent cover in pixels, spatial summary information that describes the size and arrangement of patches in the context of a larger landscape (e.g., infested regions, connected patch networks) can add a depth of information for managing invasive grasses that threaten native ecosystems. Few invasive annual grass analyses have explored the use of landscape and circuit-based connectivity metrics to characterize and compare spatial patterns of invasion. To assess the transferability and applicability of these landscape ecology analyses, we calculated landscape metrics (4 area-based, 3 configuration) and a connectivity metric (circuit-based centrality), using a weighted-average map of invasive annual grass cover in the Great Basin, USA. We calculated metrics at local and regional scales, allowing invasion statistics to be comp...
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Context 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... more
Context 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. Objectives 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. Methods 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. Resu...
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Data is available on https://chohnz.users.earthengine.app/view/wga-product-comparison-means Cheatgrass (Bromus tectorum) and other invasive annual grasses represent one of the single largest threats to the health and resilience of western... more
Data is available on https://chohnz.users.earthengine.app/view/wga-product-comparison-means Cheatgrass (Bromus tectorum) and other invasive annual grasses represent one of the single largest threats to the health and resilience of western rangelands. To address this challenge, the Western Governors Association (WGA)-appointed Western Invasive Species Council convened a cheatgrass working group to develop a new regional vision for invasive annual grass management across the West. Foundational to implementing this new vision is the creation of a common spatial map to guide strategic actions. The WGA cheatgrass working group sought to develop a 30-m base map of annual herbaceous cover to support a common spatial strategy for tackling invasive annual grasses across the western U.S. Here, we leverage three large-scale datasets to provide land managers with a product estimating the recent extent (2016-2018) of annuals across western rangelands. Input annual herbaceous datasets include Ran...
The delineation of priority areas in western North America for managing Greater Sage-Grouse (Centrocercus urophasianus) represents a broad-scale experiment in conservation biology. The strategy to limit spatial disturbance and focus... more
The delineation of priority areas in western North America for managing Greater Sage-Grouse (Centrocercus urophasianus) represents a broad-scale experiment in conservation biology. The strategy to limit spatial disturbance and focus conservation actions within delineated areas may benefit the greatest proportion of Greater Sage-Grouse. However, land use under normal restrictions outside of priority areas potentially limits dispersal and gene flow, which can isolate priority areas and lead to spatially disjunct populations. We used graph theory, representing priority areas as spatially-distributed nodes interconnected by movement corridors, to understand the capacity of priority areas to function as connected networks in the Bi-State, Central, and Washington regions of the Greater Sage-Grouse range.
Blackwell Publishing, Ltd.Assessing the value of roadless areas in a conservation reserve strategy: biodiversity and landscape connectivity in the northern Rockies
To accommodate human needs in the future, we are required to understand what disturbance processes and climatic conditions lead to the modern environment. Dendrochronology is a high-resolution application used to examine processes that... more
To accommodate human needs in the future, we are required to understand what disturbance processes and climatic conditions lead to the modern environment. Dendrochronology is a high-resolution application used to examine processes that sustain or modify both natural and human environments over shortand long-term periods (Fritts, 1971; Hughes et al., 1982; Cook and Kairiukstis, 1990). Dendrochronology provides a means to better understand environmental processes that operate over large spatial scales such as climate and wildfires. Climate ...
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logging, roads In the southern Rocky Mountains of temperate North America, the effects of Euro-American activities on dis-turbance regimes and landscape patterns have been less ubiquitous and less straightforward in high-elevation... more
logging, roads In the southern Rocky Mountains of temperate North America, the effects of Euro-American activities on dis-turbance regimes and landscape patterns have been less ubiquitous and less straightforward in high-elevation landscapes than in low-elevation landscapes. Despite apparently little change in the natural disturbance regime, there is increasing concern that forest management activities related mainly to timber harvest and to the extensive network of roads constructed to support timber harvest, fire control, and recreation since the late 1800s have altered disturbance regimes and landscape structure. We investigated the magnitude of change in landscape structure resulting from roads and logging since the onset of timber harvest activities in 1950. We found limited evidence for significant impacts in our study area when all lands within the landscape were considered. The relatively minor changes we observed reflected the vast buffering capacity of the large proportion...
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Research Interests: Ecology, Applied Ecology, Northern Rocky Mountains, Land Cover, Digital Elevation Model, and 9 moreNational Park, Protected Area, Landscape connectivity, United States Department of Agriculture, Usda Forest Service, National wildlife refuge, Ecological Applications, Reserve Design, and ENVIRONMENTAL SCIENCE AND MANAGEMENT
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To accommodate human needs in the future, we are required to understand what disturbance processes and climatic conditions lead to the modern environment. Dendrochronology is a high-resolution application used to examine processes that... more
To accommodate human needs in the future, we are required to understand what disturbance processes and climatic conditions lead to the modern environment. Dendrochronology is a high-resolution application used to examine processes that sustain or modify both natural and human environments over shortand long-term periods (Fritts, 1971; Hughes et al., 1982; Cook and Kairiukstis, 1990). Dendrochronology provides a means to better understand environmental processes that operate over large spatial scales such as climate and wildfires. Climate ...