Geology topics

Research about Moffat County, Colorado

Source-linked reports with geographic coverage including Moffat County, Colorado.

10 recordsLinked to original sources

USGS2022

Plant community trajectories following livestock exclusion for conservation vary and hinge on initial invasion and soil-biocrust conditions in shrub steppe

Adjustments or complete withdrawal of livestock grazing are among the most common conservation actions in semiarid uplands, but outcomes can vary considerably with ecological context. Invasion by exotic annual grasses and the excessive wildfire they promote are increasing threats to semiarid shrub-steppe, and plant-community response to livestock exclusion in these areas may be complicated by the rapid colonization ability of invaders. We evaluated vegetation-community changes over 14-year interval (2007–2021) in a shrub-steppe landscape where a >100-year history of livestock grazing had been terminated in 1996. Field surveys revealed that bare-soil exposure decreased >20% over the 14 years owing to biomass accumulation, but this was primarily due to large increases in exotic annual “cheatgrass” ( Bromus tectorum , +1.8-fold) and the litter it produces (+1.5-fold). Soil biocrusts increased 11.9% and perennial bunchgrasses increased 3% over the 14 years. These community changes varied at the patch scale and entailed inverse relationships of (1) both cheatgrass and biocrusts to plant-community basal cover, (2) cheatgrass to both biocrusts and perennial grasses, and (3) biocrusts to cheatgrass and litter. The spatiotemporal variability in vegetation constituted changes in plant-community states, according to cluster analysis. The modeled probability of a community transitioning to a cheatgrass state was (1) strongly and positively related to the initial (2007) cover of cheatgrass in hotspots where initial cheatgrass cover was >20%, and (2) negatively related to biocrust cover where initial biocrust cover was >4% of ground area. The decision space for this landscape can be framed as a shifting from acceptance towards resisting further degradation by removing livestock and their trampling of soil surfaces and utilization of perennial herbs. However, cheatgrass appears to be the most impactful agent of change and continued invasion appears imminent. Active restoration may help resist further degradation and direct change towards tolerable conditions.

Colorado↗

USGS2019

Managing for multiple species: Greater sage‐grouse and sagebrush songbirds

Human activity has altered 33–50% of Earth's surface, including temperate grasslands and sagebrush rangelands, resulting in a loss of biodiversity. By promoting habitat for sensitive or wide‐ranging species, less exigent species may be protected in an umbrella effect. The greater sage‐grouse ( Centrocercus urophasianus ; sage‐grouse) has been proposed as an umbrella for other sagebrush‐obligate species because it has an extensive range that overlaps with many other species, it is sensitive to anthropogenic activity, it requires resources over large landscapes, and its habitat needs are known. The efficacy of the umbrella concept, however, is often assumed and rarely tested. Therefore, we surveyed sage‐grouse pellet occurrence and sagebrush‐associated songbird abundance in northwest Colorado, USA, to determine the amount of habitat overlap between sage‐grouse and 4 songbirds (Brewer's sparrow [ Spizella breweri ], sage thrasher [ Oreoscoptes montanus ], sagebrush sparrow [ Artemisiospiza nevadensis ]), and green‐tailed towhee [ Pipilo chlorurus ]). During May and June 2013–2015, we conducted standard point count breeding surveys for songbirds and counted sage‐grouse pellets within 300 10‐m radius plots. We modeled songbird abundance and sage‐grouse pellet occurrence with multi‐scaled environmental features, such as sagebrush cover and bare ground. To evaluate sage‐grouse as an umbrella for sagebrush‐associated passerines, we determined the correlation between probability of sage‐grouse pellet occurrence and model‐predicted songbird densities per sampling plot. We then classified the sage‐grouse probability of occurrence as high (probability >0.5) and low (probability ≤0.5) and mapped model‐predicted surfaces for each species in our study area. We determined average songbird density in areas of high and low probability of sage‐grouse occurrence. Sagebrush cover at intermediate scales was an important predictor for all species, and ground cover was important for all species except sage thrashers. Areas with a higher probability of sage‐grouse occurrence also contained higher densities of Brewer's sparrows, green‐tailed towhees, and sage thrashers, but predicted sagebrush sparrow densities were lower in these areas. In northwest Colorado, sage‐grouse may be an effective umbrella for Brewer's sparrows, green‐tailed towhees, and sage thrashers, but sage‐grouse habitat does not appear to capture areas that support high sagebrush sparrow densities. A multi‐species focus may be the best management and conservation strategy for several species of concern, especially those with conflicting habitat requirements.

Colorado↗

USGS1999

Geologic map of the Skull Creek quadrangle, Moffat County Colorado

The Skull Creek quadrangle is in northwestern Colorado a few miles north of Rangely. The prominent structural feature of the Skull Creek quadrangle is the Skull Creek monocline. Pennsylvanian rocks are exposed along the axis of the monocline while hogbacks along its southern flank expose rocks that are from Permian to Upper Cretaceous in age. The Wolf Creek monocline and the Wolf Creek thrust fault, which dissects the monocline, are salient structural features in the northern part of the quadrangle. Little or no mineral potential exists within the quadrangle. A geologic map of the Lazy Y Point quadrangle, which is adjacent to the Skull Creek quadrangle on the west, is also available (Geologic Investigations Series I-2646). This companian map shows similar geologic features, including the western half of the Skull Creek monocline. The geology of this quadrangle was mapped because of its proximity to Dinosaur National Monument. It is adjacent to quadrangles previously mapped to display the geology of this very scenic and popular National Monument. The Skull Creek quadrangle includes parts of the Skull Creek Wilderness Study Area, which was assessed for its mineral resource potential.

Colorado↗

USGS1987