Geology topics

Eric Thacker

Publications and source records attributed to Eric Thacker.

5 recordsLinked to original sources

USGS2026

Long-term effects of rangeland improvements on cattle distribution: A ranch-scale case study

Resource matching can be a common assumption that underlies anthropogenic rangeland improvements for wildlife or livestock. Countless resources are spent on targeted vegetation manipulations for both livestock and wildlife, but selection for improved areas has not been well quantified in livestock. This case study investigates whether cattle exhibit preferential use of historically improved rangeland sites within sagebrush steppe ecosystems, and whether these effects are relevant long-term compared with inherent landscape heterogeneity. We used a generalized linear mixed-effects resource selection function on Global Positioning System points collected at a fix rate of 2 h from a subset of animals grazing throughout 14 pastures (totaling 13 079 ha) over 3 yr to investigate cattle distribution in relation to historical rangeland improvements. These consisted of various methods for reducing woody plant cover and increasing forage production, most followed by grass and legume reseeding. Overall selection for treated areas was positive (0.16, P < 0.0 0 01), but highly variable (pasture estimates range from-1.81 to 0.77). Differences in enhanced vegetation index (EVI) accounted for 25% of the variation in treatment selection, whereas herbaceous production did not have an appreciable effect on treatment selection. Within individual pastures, the effects of landscape variables (distance to water, slope, herbaceous production, EVI, tree cover, and shrub cover) were more variable than treatment effects and on average 2.4-fold more influential to selection than anthropogenic treatments. Still, the combined effects of all landscape variables accounted for only 8% of the variation in site selection. The observed inconsistency among selection patterns underscores the complexity of large herbivore resource selection behavior, and the statistical challenges to modeling that behavior. These results provide limited and inconsistent support for the hypothesis that large herbivores select long-term (5–20 yr post establishment) for range improvements in relation to their forage quality/quantity in a resource-matching manner.

Utah↗

USGS2024

Resilience is not enough: Toward a more meaningful rangeland adaptation science

Rangeland ecosystems, and their managers, face the growing urgency of climate change impacts. Researchers are therefore seeking integrative social-ecological frameworks that can enhance adaptation by managers to these climate change dynamics through tighter linkages among multiple scientific disciplines and manager contexts. Social-ecological framings, including resilience and vulnerability, are popular in such efforts, but their potential to inform meaningful rangeland adaptation science is limited by traditional disciplinary silos. Here, we provide reflective lessons learned from a multidisciplinary Rangelands, Ranching, and Resilience (R3) project on U.S. western rangelands that addressed 1) biophysical science projections of forage production under future climate scenarios, 2) ranchers’ views of resilience using social science methods, and 3) outreach efforts coordinated through extension professionals. Despite the project's initial intentions, human dimensions and ecological researchers largely worked in parallel sub-teams during the project, rather than weaving their expertise together with managers. The R3 project was multidisciplinary, but it provides a case study on lessons learned to suggest how social and ecological researchers can move towards approaches that transcend individual disciplines. Transdisciplinary science and management in rangelands requires more than just conceptual social-ecological frameworks. Additional methodological concepts need to include: 1) relationship building; 2) shared meaning making; and 3) a commitment to continual conversations and learning, or staying with the trouble, following Haraway (2016). If the goal is to address meaningful rangeland adaptation science rather than just produce academic products, researchers, outreach professionals, and rangeland-based communities should address a series of critical troubling questions. In the process of addressing these, deeper engagement among and beyond disciplines will occur as relationship building, shared meaning, and continual conversations and learning facilitate staying with the trouble.

Rangeland Ecology & Management↗

USGS2023

Establishing big sagebrush seedlings on the Colorado Plateau

Factors such as soil type and precipitation vary across rangeland landscapes, and these factors affect restoration outcomes and ultimately mean that “one size fits all” management strategies are not effective across large, complex landscapes. Big sagebrush (Artemisia tridentata) is a foundational rangeland species that is important to wildlife habitat across the western U.S. On the Colorado Plateau, sagebrush is important browse for ungulates, such as mule deer and pronghorn, which motivates a great deal of restoration effort. However, most scientific knowledge of big sagebrush comes from the Great Basin, and we know much less about how to restore sagebrush on the Colorado Plateau, where soils and precipitation patterns are different and conditions are warmer and drier. This fact sheet describes research about establishing and restoring sagebrush seedlings on the Colorado Plateau.

Utah↗

USGS2022

Soil depth and precipitation moderate soil textural effects on seedling survival of a foundation shrub species

In drylands, there is a need for controlled experiments over multiple planting years to examine how woody seedlings respond to soil texture and the potentially interactive effects of soil depth and precipitation. Understanding how multiple environmental factors interactively influence plant establishment is critical to restoration ecology and in this case to broad-scale restoration efforts in western US drylands dominated by big sagebrush ( Artemisia tridentata ). We planted sagebrush seedlings across a range of soil textures and depths in the southern portion of the species' range, on the Colorado Plateau. We evaluated survival of repeated plantings of caged and uncaged seedlings over two years across 20 plots in wet vs. average precipitation years at one site, and examined broader patterns of sagebrush seedling survival during an average precipitation year in 56 plots across four sites. First-year survival was >9x higher under wet than average precipitation. Under favorable (wet) conditions, early sagebrush seedling survival was highest on coarser soils, especially those that also had a shallower restrictive layer (e.g., 50-100 cm). Under average precipitation, soil texture and depth effects on survival of newly-planted seedlings were much weaker, but older (>1 yr) seedlings benefitted from growing on coarser textured soils. It may be possible to increase survival by sheltering seedlings with small mesh cages, which likely improve moisture availability. Our results provide new insights into environmental factors that limit woody seedling survival in drylands and illustrate that planting in wet years and incorporating detailed soil setting information could increase survival of sagebrush seedlings in restoration projects.

Restoration Ecology↗

USGS2021

Making research relevant: Sharing climate change research with rangeland advisors to transform results into drought resilience

On the Ground • Public programs, strategies, and incentives to implement rangeland climate adaptation are more effective if they are tailored to local drought exposures, sensitivities, and adaptation opportunities. As such, local rangeland advisers who aid in climate adaptation are pivotal to the development of these resources. • We hosted a virtual workshop with rangeland advisors to share results from our climate vulnerability assessment, gain their insight on finding usability, and discuss visions for resource creation. • Climate adaptation resources should not follow a one-size-fits-all approach. Accommodating variety in resource development and outreach must consider multiple factors: variation in the ranching community, instability in the environment beyond climate, and rancher/manager identified variables in climate vulnerability assessment analyses.

Rangelands↗