Research and Publications
In situ measurements of sagebrush have traditionally been expensive and time consuming. Currently, improvements in small Unmanned Aerial Systems (sUAS) technology can be used to quantify sagebrush morphology and community structure with high resolution imagery on western rangelands, especially in sensitive habitat of the Greater sage-grouse (Centrocercus urophasianus). The emergence of photogrammetry algorithms to generate 3D point clouds from true color imagery can potentially increase the efficiency and accuracy of measuring shrub height in sage-grouse habitat. Our objective was to determine optimal parameters for measuring sagebrush height including flight altitude, single- vs. double- pass, and continuous vs. pause features. We acquired imagery using a DJI Mavic Pro 2 multi-rotor Unmanned Aerial Vehicle (UAV) equipped with an RGB camera, flown at 30.5, 45, 75, and 120 m and implementing single-pass and double-pass methods, using continuous flight and paused flight for each photo method. We generated a Digital Surface Model (DSM) from which we derived plant height, and then performed an accuracy assessment using on the ground measurements taken at the time of flight. We found high correlation between field measured heights and estimated heights, with a mean difference of approximately 10 cm (SE = 0.4 cm) and little variability in accuracy between flights with different heights and other parameters after statistical correction using linear regression. We conclude that higher altitude flights using a single-pass method are optimal to measure sagebrush height due to lower requirements in data storage and processing time.
This study quantified seasonal second‐order habitat selection for sage‐grouse across the state of Utah to produce spatio‐temporal predictions of their distribution at the southern periphery of the species range. We used location data obtained from sage‐grouse marked with very‐high‐frequency radio‐transmitters and lek location data collected between 1998 and 2013 to quantify species habitat selection in relation to a suite of topographic, edaphic, climatic, and anthropogenic variables using random forest algorithms. Sage‐grouse selected for greater sagebrush (Artemisia spp.) cover, higher elevations, and gentler slopes and avoided lower precipitations and higher temperatures. The strength of responses to habitat variables varied across seasons. Anthropogenic variables previously reported as affecting their range‐wide distribution (i.e., roads, powerlines, communication towers, and agricultural development) were not ranked as top predictors at our focal scale. Other than strong selection for sagebrush cover, the responses we observed differed from what has been reported at the range‐wide scale. These differences likely reflect the unique climatic, geographic, and topographic context found in the southern peripheral area of the species distribution compared to range‐wide environmental gradients. Our results highlight the importance of considering appropriateness of scale when planning conservation actions for wide‐ranging species.
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Resilience goals should be updated to better apply to 21st century ecosystems. They propose a concept of scaled resilience, which incorporates scales of time, space, and biological level of organization. By measuring disturbance and post-disturbance ecosystem responses in all three dimensions, scaled resilience models can be grounded by data that are much more useful to land managers than simple comparisons to reference site conditions.
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Making lands resilient to climate change has become a legal mandate for US Forest Service land planners (2012 USFS Planning Rule). However, interpreting and applying the directive is challenging because the term “resilience” is rather vague. It is diluted by a variety of definitions in the literature, as well as executed differently in diverse ecosystems by a variety of specialists.
To better grasp how USFS staff interpreted and applied the directive, twenty-six Southwestern Region USFS planners and mangers were interviewed for 30-60 minutes each. The semi-structured interviews were then coded to identify themes and trends. Overall, inductive content analysis of the coded interview data showed that the interviewees had three main areas of concern over the difficulty in reporting and implementing the resilience directive: 1) definitions and scale, 2) flexibility and specificity, and 3) the resilience to climate change paradox.
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Ecosystems worldwide are facing complex interacting stressors that are leading to rapid and potentially irreversible change. Many of these changes involve vegetation type-conversion in various stages and forms. A variety of terms are applied to changes in ecosystems around the world to describe some aspect of long-lasting changes in plant communities. Here we evaluate a representative list of analogous terms for processes and patterns involved in vegetation type-conversion, highlighting similarities and differences. The list illustrates a common problem in ecology, viz. how similar terminology may actually describe different aspects of complex processes. Linking this terminology under a unified, umbrella concept of vegetation type conversion and placing it into the context of an ecological resilience framework, including community reorganization, may help resolve research agendas and conservation efforts.
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Climate change is increasing the risk of extreme events, resulting in social and economic challenges. I examined recent past (1971–2000), current and near future (2010-2039), and future (2040-2069) fire and heat hazard combined with population growth by different regions and residential densities (i.e., exurban low and high densities, suburban, and urban low and high densities). Regional values for extreme fire weather days varied greatly. Temperature and number of extreme fire weather days increased over time for all residential density categories, with the greatest increases in the exurban low-density category. The urban high-density category was about 0.8 to 1 °C cooler than the urban low-density category. The areas of the urban and suburban density categories increased relative to the exurban low-density category. Holding climate change constant at 1970-2000 resulted in a temperature increase of 0.4 to 0.8 °C by 2060, indicating future population increases in warmer areas. Overall, U.S. residents will experience greater exposure to fire hazard and heat over time due to climate change, and compound risk emerges because fire weather and heat are coupled and have effects across sectors. Movement to urban centers will help offset exposure to fire but not heat, because urban areas are heat islands; however, urban high-density areas had lower base temperatures, likely due to city locations along coastlines. This analysis provides a timely look at potential trends in fire and heat risk by residential density classes due to the expansion and migration of US populations.
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This study shows that simultaneous wildfire is at least as correlated with preparedness levels as other burned area measures and identify changes in simultaneous wildfire occurrence within the western and southern United States. Seasonal variation and spatial autocorrelation in simultaneous wildfire occurrence provide evidence of coupling of wildfire activity in portions of the western United States. Best-approximating models of simultaneity suggest that high levels of simultaneous wildfire often coincided with low fuel moisture and high levels of lightning occurrence. Model uncertainty was high in some contexts but, with only a few exceptions, there was strong evidence that the best model should include both a dryness and lightning indicator.
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Abstracts of Recent Papers on Range Management in the West. Prepared by Charlie Clements, Rangeland Scientist, USDA Agricultural Research Service, Reno, NV.
Across the western US, severe wildfires fueled by tinder-dry vegetation have already burned more than 3.2 million hectares (8 million acres) — an area the size of Maryland — as of the end of October, 2020, and nearly six times that area burned this year in Australia. And even though neither country’s worst-ever fire year is not yet over, concerns are already mounting regarding the next hazard these regions will face: dangerous and destructive debris flows.
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Across the United States, millions of acres of land have been so disturbed by human activities or severe climate events that significant portions of their native plant communities have been lost and their ecosystems have been seriously compromised. Restoring impaired ecosystems requires a supply of diverse native plant seeds that are well suited to the climates, soils, and other living species of the system. Native seeds are also in demand for applications in urban land management, roadside maintenance, conservation agriculture, and other restorative activities that take into account the connection between native plant communities and the increasingly urgent need for resilient landscapes. Given the varied climatic and environmental niches of the more than 17,000 native plant species of the United States, supplying the desired seed types and species mixes for this wide range of activities is a challenge.