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At least 487 records · Page 27Linked to original sources
USGS2026

Understanding the links between functional performance and environment in cold desert ecosystems through the flagship biocrust forming moss Syntrichia caninervis

Background and aims Biocrust communities shape the soil surface in drylands, regulating important ecosystem properties. Despite this, few works address key functional attributes in these poikilohydric photosynthetic communities, including the length of metabolic activity in the field and its relationship with microclimate. We aim to disentangle the links between functional performance of a keystone biocrust species and environment in drylands, in order to better understand ecosystem functioning and services provided to the soil by these organisms. Methods We developed a 23 months monitoring experiment using very high resolution measurements of chlorophyll a fluorescence and microclimate in the field, comparing habitats with soils of different particle size composition and microclimatic conditions for the flagship biocrust moss Syntrichia caninervis on the Colorado Plateau, Utah, USA. Results While growing in soils of different composition did not impair the functional performance of the species, the sun/shade plasticity did affect key physiological attributes. Our results quantified a strategy based on avoidance of the most extreme environmental conditions, where metabolic activity only occur during 19.9% of the total time monitored. Relative humidity was the best microclimatic predictor of metabolic activity, and the annual length of metabolically active periods showed strong convergences with other drylands of the world. Conclusions These results collectively suggest a strong control of the environment over the ecosystem services provided by biocrusts. Our results include evidence for an improved understanding of the plasticity of S. caninervis to its variety of habitats, and its response to potential threats under different climate change scenarios.

Utah↗
USGS2018

Landscape pivot points and responses to water balance in national parks of the southwest US

A recent drying trend that is expected to continue in the southwestern US underscores the need for site‐specific and near real‐time understanding of vegetation vulnerability so that land management actions can be implemented at the right time and place. We related the annual integrated normalized difference vegetation index (iNDVI), a proxy for vegetation production, to water balance across landscapes of the Colorado Plateau. We determined how changes in production per unit of water (vegetation responses) and the water balance amounts at which production shifted from above to below average values (pivot points), varied across dominant vegetation and soil types. Precipitation (PRCP), actual evapotranspiration (AET), water deficit ( D ), and soil moisture (SM) explained 13%–82% of variation in vegetation production. Along an increasing water availability gradient, vegetation responses to PRCP and AET increased, responses to SM decreased, and responses to D became more negative. We found trade‐offs between vegetation responses and pivot points within and across all vegetation types that were mediated by soil properties. Synthesis and applications . The water needed by native vegetation to maintain production depends on plant traits. The water available to vegetation depends on climate and soil properties that change along environmental gradients. Tracking this biologically relevant water availability in relation to water need provides an indicator of vegetation growth or stress that can help guide the time and place for management actions.

Colorado, Utah↗
USGS2022

Supporting the development and use of native plant materials for restoration on the Colorado Plateau (Fiscal Year 2021 Report)

A primary focus of the Colorado Plateau Native Plant Program (CPNPP) is to identify and develop appropriate native plant materials (NPMs) for current and future restoration projects. Multiple efforts have characterized the myriad challenges inherent in providing appropriate seed resources to enable effective, widespread restoration and have identified a broad suite of research activities to provide the information necessary to overcome those challenges (e.g., Plant Conservation Alliance 2015; Breed et al. 2018; Winkler et al. 2018; McCormick et al. 2021). Many of the most complex information needs relate to identifying the appropriate sources of plant species that can successfully establish in dryland environments, like the Colorado Plateau, where low and highly variable precipitation is standard. Providing this information requires synergistic research efforts in which results from earlier investigations inform the design of subsequent investigations. The U.S. Geological Survey (USGS) Southwest Biological Science Center’s (SBSC’s) research activities to support CPNPP in FY21 followed the FY21 Statement of Work to support a research framework that is continually adapting based on the needs of the restoration community and results from previous investigations; the long-term research framework is outlined in the 2019-2023 5-Year Research Strategy (hereafter referred to as the 5-year plan). This research framework provides support for the National Seed Strategy for Rehabilitation and Restoration (Plant Conservation Alliance 2015), Biden-Harris Administration Executive Order 14008 (Tackling the Climate Crisis at Home and Abroad), and Department of Interior Priority #4 (Working to conserve at least 30% each of our lands and waters by the year 2030). Research activities in FY21 centered on landscape genomics, implementing and monitoring a common garden experiment near Vernal, UT, conducting experimental treatments using the GRID (Germination for Restoration Information and Decision-making) framework, and initiating new genetics projects to investigate the impact of production techniques on plant materials and restoration treatments on native plant communities. These activities were supported by four biological science technicians. The SARS-CoV-2 pandemic delayed some aspects of the FY21 workplan, especially for outside laboratory services. However, goals were largely met, and the overall progress of research remains on track with respect to the 5-year plan. While Dr. Rob Massatti was the only scientist supported by the SBSC-CPNPP agreement in FY21, other scientists, including Drs. John Bradford, Seth Munson, Mike Duniway, Sasha Reed, and Daniel Winkler, spent a considerable amount of time providing expertise and support for individual projects. Work activities performed in support of each 5-year plan goal are discussed in turn. Products resulting from FY21 research activities are reported in Appendix 1.

Arizona, Colorado, New Mexico, Utah↗
USGS2023

Supporting the development and use of native plant materials for restoration on the Colorado Plateau (Fiscal Year 2022 Report)

A primary focus of the Colorado Plateau Native Plant Program (CPNPP) is to identify and develop appropriate native plant materials (NPMs) for current and future restoration projects. Multiple efforts have characterized the myriad challenges inherent in providing appropriate seed resources to enable effective, widespread restoration and have identified a broad suite of research activities to provide the information necessary to overcome those challenges (e.g., Plant Conservation Alliance, 2015; Breed et al., 2018; Winkler et al., 2018; NASEM, 2023). Many of the most complex information needs relate to identifying the appropriate sources of plant species that can successfully establish in dryland environments, like the Colorado Plateau, where low and highly variable precipitation is standard. Providing this information requires synergistic research efforts in which results from earlier investigations inform the design of subsequent investigations. The U.S. Geological Survey (USGS) Southwest Biological Science Center’s (SBSC’s) research activities to support CPNPP in FY22 followed the FY22 Statement of Work to support a research framework that is continually adapting based on the needs of the restoration community and results from previous investigations; the long-term research framework is outlined in the 2019-2023 5-Year Research Strategy (hereafter referred to as the 5-year plan). This research framework provides support for the National Seed Strategy for Rehabilitation and Restoration (Plant Conservation Alliance, 2015), Biden-Harris Administration Executive Order 14008 (Tackling the Climate Crisis at Home and Abroad), and Department of Interior Priority #4 (Working to conserve at least 30% each of our lands and waters by the year 2030). Research activities in FY22 centered on landscape genomics, monitoring common garden and seeding experiments near Vernal and Moab, UT, conducting experimental treatments using the GRID (Germination for Restoration Information and Decision-making) framework, and continuing newer genetics projects to investigate the impact of productions techniques on plant materials and restoration treatments on native plant communities. These activities were supported by two biological science technicians. The effects of the SARS-CoV-2 pandemic were less visible in FY22, allowing SBSC to catch up on backlogged laboratory work. The overall progress of SBSC’s research remains on track with respect to the 5-year plan. While Dr. Rob Massatti was the only scientist supported by the SBSC-CPNPP agreement in FY22, other scientists, including Drs. John Bradford, Seth Munson, Mike Duniway, Sasha Reed, and Daniel Winkler, spent a considerable amount of time providing expertise and support for individual projects. Work activities performed in support of each 5-year plan goal are discussed in turn.

Colorado Plateau↗
USGS2023

The Colorado River water crisis: Its origin and the future

During much of the 21st century, natural runoff in the Colorado River basin has declined, while consumption has remained relatively constant, leading to historically low reservoir storage. Between January 2000 and April 2023, the amount of water stored in Lake Mead and Lake Powell, the two largest reservoirs in the United States, declined by 33.5 million acre feet (41.3 billion cubic meters). As of April 2023, total basin-wide storage was sufficient to support the 21st century average rate of basin-wide consumption for only 15 months. Runoff in spring 2023 is predicted to be large, providing a short-term reprieve. However, it will take four to five additional unusually wet years in succession to refill Lake Powell and Lake Mead if basin-wide water use remains unchanged. Increasing evapotranspiration and dry soils associated with global climate change makes such a scenario unlikely. To stabilize reservoir storage, basin-wide use needs to equal modern runoff. To recover reservoir storage, basin-wide use needs to decline even more. Based on 21st century average runoff, a 13%–20% decline in basin-wide use would allow for stabilization and some reservoir storage recovery. Future policy debate about reservoir operations will inevitably concern whether most, or all, reservoir storage should be in Lake Mead or in Lake Powell. The choice of one or the other will result in significantly different environmental and recreational outcomes for Glen Canyon and the Grand Canyon.

Arizona, Baja California, California, Colorado, Ne↗
USGS1994

Correlation of basinal carbonate cycles to nearshore parasequences in the Late Cretaceous Greenhorn seaway, Western Interior U.S.A.

Upper Cretaceous limestone-shale couplets developed within the late transgressive stage of the Greenhorn cyclothem may be correlated from carbonate-dominated (basinal) sequences in central Kansas and Colorado westward to clastic cycles in southern Utah. Six such basinal couplets have been traced to corresponding upward-coarsening progradational cycles developed on the western margin of the Western Interior basin. In the central basin in Colorado and Kansas, these sedimentary cycles are represented by limestone-shale and marlstone-shale couplets ∼0.5-1.0 m in thickness. More calcareous parts of these couplets may be correlated westward into condensed, fossiliferous concretion and shell beds in proximal offshore lithofacies of Arizona and Utah. These concretion and shell beds are physically traceable farther landward (westward) into bioturbated, fossil-rich, transgressive lag deposits that bound 10- to 20-m-thick coarsening-upward progradational strand-plain deposits (parasequences) in southwestern Utah. Thus, the progra-dational phase of parasequence deposition correlates with accumulation of clay-rich sediment in the central basin, and the transgressive phase is characterized by reduced terrigenous input and deposition of carbonate-rich sediment. We consider Milankovitch-style orbital forcing of climate and tectonically induced fluctuations in rates of foredeep basin subsidence as possible forcing mechanisms for these basinwide events. Based on the widespread distribution of the limestone-shale couplets, as well as on estimated sedimentation rates and geochronology, it has been widely speculated that these carbonate cycles reflect Milankovitch cycles with periodicities on the order of 20 k.y. to 100 k.y. If so, then stratigraphic data suggest that orbital forcing of climate affected eustasy and/or sediment input and biogenic production in the Western Interior basin. Alternatively, thrusting events in the Sevier orogenic belt may have produced episodic changes in the rates of foredeep basin subsidence and consequent changes in base level, which could have controlled the deposition of the Greenhorn parasequences and carbonate cycles. In either case, correlation of these units demonstrates a consistent basinwide sedimentary response to high-frequency base level or sediment input changes in the Western Interior epicontinental basin.

Arizona, Colorado, Kansas, Utah↗
USGS2007

A stand-replacing fire history in upper montane forests of the southern Rocky Mountains

Dendroecological techniques were applied to reconstruct stand-replacing fire history in upper montane forests in northern New Mexico and southern Colorado. Fourteen stand-replacing fires were dated to 8 unique fire years (1842–1901) using four lines of evidence at each of 12 sites within the upper Rio Grande Basin. The four lines of evidence were ( i ) quaking aspen ( Populus tremuloides Michx.) inner-ring dates, ( ii ) fire-killed conifer bark-ring dates, ( iii ) tree-ring width changes or other morphological indicators of injury, and ( iv ) fire scars. The annual precision of dating allowed the identification of synchronous stand-replacing fire years among the sites, and co-occurrence with regional surface fire events previously reconstructed from a network of fire scar collections in lower elevation pine forests across the southwestern United States. Nearly all of the synchronous stand-replacing and surface fire years coincided with severe droughts, because climate variability created regional conditions where stand-replacing fires and surface fires burned across ecosystems. Reconstructed stand-replacing fires that predate substantial Anglo-American settlement in this region provide direct evidence that stand-replacing fires were a feature of high-elevation forests before extensive and intensive land-use practices (e.g., logging, railroad, and mining) began in the late 19th century.

Canadian Journal of Forest Research↗
USGS2015

Evidence of a higher late-Holocene treeline along the Continental Divide in central Colorado

Using a combination of 23 radiocarbon ages and annual ring counts from 18 Rocky Mountain bristlecone pine ( Pinus aristata ) remnants above the local present-day limits, a period of higher treeline has been determined for two sites near the Continental Divide in central Colorado. The highest remnants were found about 30 m above live bristlecone pines of similar size. The majority of the remnants, consisting of standing snags, large logs, and smaller remains, are highly eroded, such that the innermost annual rings of all but one are missing. The radiocarbon ages obtained from the oldest wood recovered from each remnant indicate that the majority were established above the present-day limit of bristlecone pine from prior to 2700 cal. yr BP to no later than about 1200 cal. yr BP. These radiocarbon ages combined with the annual ring count from the corresponding remnant indicate that the majority of the sampled remnants grew above the present-day limit of bristlecone pine from sometime before 2700 cal. yr BP to about 800 cal. yr BP. Evidence of recent climatic warming is demonstrated at one of the sites by young bristlecone pine saplings growing next to the highest remnants; the saplings were established after AD 1965 and represent the highest advance of treeline in at least 1200 years.

Colorado↗
USGS2015

Resilience of ponderosa and lodgepole pine forests to mountain pine beetle disturbance and limited regeneration

After causing widespread mortality in lodgepole pine forests in North America, the mountain pine beetle (MPB) has recently also affected ponderosa pine, an alternate host species that may have different levels of resilience to this disturbance. We collected field data in ponderosa pine- and lodgepole pine-dominated forests attacked by MPB in Colorado and then simulated stand growth over 200 years using the Forest Vegetation Simulator. We compared scenarios of no disturbance with scenarios of MPB-caused mortality, both with and without regeneration. Results indicated that basal area and tree density recovered to predisturbance levels relatively rapidly (within 1‐8 decades) in both forest types. However, convergence of the disturbed conditions with simulated undisturbed conditions took longer (12‐20+ decades) and was delayed by the absence of regeneration. In MPB-affected ponderosa pine forests without regeneration, basal area did not converge with undisturbed conditions within 200 years, implying lower resilience in this ecosystem. Surface fuels accumulated rapidly in both forest types after MPB-induced mortality, remaining high for 3‐6 decades in simulations. Our results suggest that future patterns of succession, regeneration, fuel loading, climate, and disturbance interactions over long time periods should be considered in management strategies addressing MPB effects in either forest type, but particularly in ponderosa pine.

Forest Science↗
USGS2025

Quantifying regional ecological dynamics using agency monitoring data, ecological site descriptions, and ecological site groups

Information about what ecological conditions are likely, causes or drivers of degradation, and potential management actions to restore degraded lands may support land conservation and restoration decisions. State-and-transition models (STMs) describe persistent plant and ecological conditions that are possible (the “state”) within a given abiotic setting and drivers or actions that can cause shifts between states (the “transitions”). These primarily conceptual models are widely used to inform resource and conservation decisions. Data-driven STMs have been developed for some lands, but not at regional or national scales. Here, we demonstrate a new repeatable workflow for developing data-driven STMs in the United States (US). The approach leverages predictive maps of Ecological Site Groups (ESGs), extensive field-based Federal monitoring databases, information from Ecological Site Description (ESD) STMs, soil erosion models, remotely sensed productivity, and other available spatial information (fire, land protection, and drought) to provide context and descriptions of the data-driven states, including likely drivers of transitions. Results of this workflow applied to one dryland ESG in the Upper Colorado River Basin in the southwestern US suggest that an Invaded state (16% of 1352 plots) and some occurrences of a Grassland state (30% of plots) are in a degraded or at-risk condition with reduced ecosystem services. The most common drivers of state transitions in the associated ESDs ( n = 26) are related to livestock grazing and fire. The Invaded state in the ESG has evidence of degraded habitat quality and accelerated run-off while the Grassland state occurrences show reduced richness, productivity, and elevated erosion risk by wind. Areas subject to wildfire and with lower protection status had greater probability of Invaded state occurrence, generally supporting drivers in ESDs. The workflow presented here can serve as a template for describing ecological dynamics at regional scales, and support prioritization of land for conservation and climate adaptation activities.

Rangeland Ecology & Management↗
USGS1992

The oldest known Rocky Mountain bristlecone pines ( Pinus aristata Engelm.)

We have found 12 living Rocky Mountain bristlecone pines ( Pinus aristata ) more than 1600 yr old, including four that are more than 2100 yr old, on Black Mountain, near South Park, and on Almagre Mountain, in the southern Front Range, Colorado. A core from the oldest of these trees has an inner-ring date of 442 B.C. This tree is therefore at least 2435 yr old and exceeds the age of the oldest previously reported Rocky Mountain bristlecone pine by 846 yr. The ages of these trees show that Rocky Mountain bristlecone pines, under arid environmental conditions, achieve much older ages than have been previously reported. The ages also show that previously inferred trends in bristlecone pine ages, where maximum ages in the eastern range of Rocky Mountain bristlecone pines are much less than maximum ages in the western range of Great Basin bristlecone pines ( Pinus longaeva ), are less strong than previously supposed. Ancient Rocky Mountain bristlecone pines, such as those found in this study, have the potential to expand our knowledge of late Holocene climatic conditions in western North America.

Arctic and Alpine Research↗
USGS1994

Hydrology and geochemistry of a surface coal mine in northwestern Colorado

The hydrology and geochemistry of a reclaimed coal mine in northwestern Colorado were monitored during water years 1988 and 1989. Some data also were collected in water years 1987 and 1990. This report describes (1) the sources of hydrologic recharge to and discharge from reclaimed spoil, (2) the relative contributions of recharge to the reclaimed spoil aquifer from identified source waters and the rate of water movement from those sources to the reclaimed spoil, and (3) the geochemical reactions that control water quality in reclaimed spoil. The study area was at a dip-slope coal mine encompassing about 7 square miles with land slopes of varying aspect. The area was instrumented and monitored at five sites; two sites had unmined and reclaimed- spoil areas adjacent to each other and three sites were unmined. The mined areas had been reclaimed. Instrumentation at the study sites included 1 climate station, 3 rain gages, 19 soil-water access tubes, 2 lysimeters, 18 wells completed in bedrock, 7 wells completed in reclaimed spoil, and 2 surface- water gaging stations. The results of the study indicate that the reclaimed spoil is recharged from surface recharge and underburden aquifers. Discharge, as measured by lysimeters, was about 3 inches per year and occurred during and after snowmelt. Hydraulic-head measurements indicated a potential for ground-water movement from deeper to shallower aquifers. Water levels rose in the reclaimed-spoil aquifer and spring discharge at the toe of the spoil slopes increased rapidly in response to snowmelt. Water chemistry, stable isotopes, geochemical models, and mass-balance calculations indicate that surface recharge and the underburden aquifers each contribute about 50 percent of the water to the reclaimed-spoil aquifers. Geochemical information indicates that pyrite oxidation and dissolution of carbonate and efflorescent sulfate minerals control the water chemistry of the reclaimed-spoil aquifer.

Water-Resources Investigations Report↗
USGS2025

A Colorado Front Range grassland exhibits decreasing dominance of cheatgrass (Bromus tectorum) over time

Causes, consequences, and potentials for recovery from invasions by the invasive annual grass, cheatgrass ( Bromus tectorum ), in western North America have been extensively documented. The vast majority of these studies have come from regions where yearly precipitation is dominated by “winter-wet” patterns, but this species has also demonstrated its ability to invade plant communities in “spring/summer-wet” areas as well. In grasslands of the Front Range of Colorado, a region experiencing a “spring/summer-wet” precipitation pattern, cheatgrass can exploit early-season soil moisture, but moderate rainfall continues into the growing season beyond the time of cheatgrass senescence. In this study, we measured how cheatgrass dominance changed over a 13-year interval in a disturbed meadow along the Front Range of Colorado with a “spring/summer-wet” precipitation pattern. Cheatgrass cover declined in absolute abundance by about 50% while total vegetation cover increased over this time period. The site was neither grazed nor burned during this interval. A “spring/summer-wet” precipitation pattern with high interannual variation in amounts occurred during the study, but no relationships between the seasonality or amounts of precipitation and the directional decline in cheatgrass abundance were observed. Rainout shelter manipulations showed that the seasonality of precipitation influenced cheatgrass abundance, with winter drought treatments reducing cheatgrass cover relative to plots that experienced summer drought treatments. The cheatgrass decline corresponded with a lesser decline in native grass cover and no change in native forb cover, while the abundance of non-native perennial grasses and forb species increased over the study interval. Although cheatgrass can invade communities across broad climatic gradients following disturbance, results from this study show that the persistence of cheatgrass within invaded areas may depend on the seasonality of precipitation and plant communities that vary across these gradients.

Colorado↗
USGS2022

Conflict of energies: Spatially modeling mule deer caloric expenditure in response to oil and gas development

Context Wildlife avoid human disturbances, including roads and development. Avoidance and displacement of wildlife into less suitable habitat due to human development can affect their energy expenditures and fitness. The heart rate and oxygen uptake of large mammals varies with both natural aspects of their habitat (terrain, climate, predators, etc.) and anthropogenic influence (noise, light, fragmentation, etc.). Although incorporating physiological analyses of energetics can inform the impacts of both development and conservation, management decisions rarely incorporate individuals’ energetic requirements when deciding on locations for potential development. Objectives We aimed to estimate the change in expected energy expenditure, numerically and spatially, for mule deer to traverse a landscape with varying levels of oil and gas development through time. Methods Using calculations of energy expenditure of mule deer ( Odocoileus hemionus ) by weight, in relation to physical terrain components, plus avoidance factors for anthropogenic disturbance, we developed a spatiotemporal model of the minimum energy required for mule deer to traverse a landscape. We compared expected energy expenditure across 12 study sites with increasing levels of oil and gas development and over time in our study area, on the northern Colorado Plateau of Utah. Results We found that energy expenditure can be increased by development, regardless of terrain, through increased travel distance associated with avoidance behavior. Maximum median energy expenditure to traverse a 1400 ha sample area rose from 1135 to 1935 kilocalories, a 70% increase in energy required of a mule deer. There was a significant relationship between energy expenditure and the size of oil and gas development (p < 0.001), its compactness (p < 0.05), and its ‘thinness’ (p < 0.001), but not terrain ruggedness (p = 0.25). Conclusion As the energy costs of movement correlate across multiple species of large mammals, our analysis of the energetic cost, for mule deer, associated with development can serve as a quantitative representative of the impacts of oil and gas development for multiple mammals—including threatened or endangered species. Our bioenergetic cost-distance model provides a means of delineating impediments to efficient movement and can be used to quantify the expected energetic costs of proposed future developments. As wildlife are exposed to increasing anthropogenic stressors which reduce fitness, it is important to make strategic siting decisions to reduce energetic costs imposed by human activities.

Utah↗
USGS1969

Hydrology of the San Luis Valley, south-central Colorado

An investigation of the water resources of the Colorado part of the San Luis Valley was begun in 1966 by the U.S. Geological Survey, in cooperation with the Colorado Water Conservation Board. (See index map, fig. 1). The purpose of the investigation is to provide information for planning and implementing improved water-development and management practices. The major water problems in the San Luis Valley include (1) waterlogging, (2) waste of water by nonbeneficial evapotranspiration, (3) deterioration of ground-water chemical quality, and (4) failure of Colorado to deliver water to New Mexico and Texas in accordance with the Rio Grande Compact. This report describes the hydrologic environment, extent of water-resource development, and some of the problems related to that development. Information presented is based on data collected from 1966 to 1968 and on previous studies. Subsequent reports are planned as the investigation progresses. The San Luis Valley extends about 100 miles from Poncha Pass near the northeast corner of Saguache County, Colo., to a point about 16 miles south of the Colorado-New Mexico State line. The total area is 3,125 square miles, of which about 3,000 are in Colorado. The valley is nearly flat except for the San Luis Hills and a few other small areas. The Colorado part of the San Luis Valley, which is described in this report, has an average altitude of about 7,700 feet. Bounding the valley on the west are the San Juan Mountains and on the east the Sangre de Cristo Mountains. Most of the valley floor is bordered by alluvial fans deposited by streams originating in the mountains, the most extensive being the Rio Grande fan (see block diagram, fig. 2 in pocket). Most of the streamflow is derived from snowmelt from 4,700 square miles of watershed in the surrounding mountains. The northern half of the San Luis Valley is internally drained and is referred to as the closed basin. The lowest part of this area is known locally as the "sump." The remainder of the valley is drained by the Rio Grande and its tributaries. The climate of the San Luis Valley is arid, and a successful agricultural economy would not be possible without irrigation. It is characterized by cold winters, moderate summers, and much sunshine. The average annual precipitation on the valley floor ranges from 7 to 10 inches. More than half the precipitation occurs from July to September. Moisture deficiency in the valley is shown by the graph comparing pan evaporation and precipitation {fig. 3}. For the years 1961-67 average pan evaporation for the period April through September was 52.25 inches, but average precipitation for the period was only 5.02 inches. Average annual precipitation was 7.8 inches. Owing to the short growing season (90-120 days), crops a.re restricted mainly to barley, oats, potatoes, and other vegetables.

Colorado↗
USGS2007

Mass Wasting Following the 2002 Missionary Ridge Fire near Durango, Colorado, a Field Trip Guidebook

This field trip guide focuses on mass wasting following the 2002 Missionary Ridge fire near Durango, Colorado. We prepared this guide to accompany a May 4, 2006, field trip during the second Roy J. Shlemon Specialty Conference, which was held in Durango, Colorado, May 3-5. The conference, entitled Mass Wasting in Disturbed Watersheds, was sponsored by the Association of Environmental & Engineering Geologists (AEG) and the AEG Foundation. The objective of this Shlemon Conference was to bring together practitioners and researchers to define the current state of practice and identify unresolved problems with regard to the prediction and mitigation of mass wasting in disturbed watersheds. The one-day field trip begins and ends in Durango. Many of the field trip stops are at debris-flow fans around the periphery of the burn area, but one stop examines landslide activity in the burn area that initiated during spring 2005 snowmelt within a dormant, deep-seated landslide, as well as an erosion/debris-flow mitigation effort in a drainage basin above Lemon Reservoir. Also provided are descriptions of the Missionary Ridge fire, the geologic and climatic setting of the field-trip area, and the general effects of wildfire on watersheds.

Open-File Report↗
USGS2018

Landsat time series analysis of fractional plant cover changes on abandoned energy development sites

Oil and natural gas development in the western United States has increased substantially in recent decades as technological advances like horizontal drilling and hydraulic fracturing have made extraction more commercially viable. Oil and gas pads are often developed for production, and then capped, reclaimed, and left to recover when no longer productive. Understanding the rates, controls, and degree of recovery of these reclaimed well sites to a state similar to pre-development conditions is critical for energy development and land management decision processes. Here we use a multi-decadal time series of satellite imagery (Landsat 5, 1984–2011) to assess vegetation regrowth on 365 abandoned well pads located across the Colorado Plateau in Utah, Colorado, and New Mexico. We developed high-frequency time series of the Soil-Adjusted Total Vegetation Index (SATVI) for each well pad using the Google Earth Engine cloud computing platform. BFAST time-series models were used to fit temporal trends, identifying when vegetation was cleared from the site and the magnitudes and rates of vegetation change after abandonment. The time series metrics are used to calculate the relative fractional vegetation cover (RFVC) of each pad, a measure of post-abandonment vegetation cover relative to pre-drilling condition. Mean and median RFVC were 36% (s.d. 33%) and 26%, respectively, five years after abandonment, with one third of well pads having RFVC greater than 50%. Statistical analyses suggest that much of the high vegetation cover is associated with weedy invasive annual species such as cheatgrass (Bromus tectorum) and Russian thistle (Salsola spp.). Climate conditions and the year of abandonment also play a role, with increased cover in later years associated with a wetter period. Non-linear change at many pads suggests longer recovery times than would be estimated by linear extrapolation. New techniques implemented here address a complex response of cover change to soils, management, and climate over time, and can be extended to the operational monitoring of energy development across large areas.

International Journal of Applied Earth Observation↗
USGS2009

Preliminary Map of Landslide Deposits in the Mesa Verde National Park Area, Colorado

This report presents a preliminary map of landslide deposits in the Mesa Verde National Park area (see map sheet) at a compilation scale of 1:50,000. Landslide is a general term for landforms produced by a wide variety of gravity-driven mass movements, including various types of flows, slides, topples and falls, and combinations thereof produced by the slow to rapid downslope transport of surficial materials or bedrock. The map depicts more than 200 landslides ranging in size from small (0.01 square miles) earthflows and rock slumps to large (greater than 0.50 square miles) translational slides and complex landslides (Varnes, 1978). This map has been prepared to provide a regional overview of the distribution of landslide deposits in the Mesa Verde area, and as such constitutes an inventory of landslides in the area. The map is suitable for regional planning to identify broad areas where landslide deposits and processes are concentrated. It should not be used as a substitute for detailed site investigations. Specific areas thought to be subject to landslide hazards should be carefully studied before development. Many of the landslides depicted on this map are probably stable as they date to the Pleistocene (approximately 1.8-0.011 Ma) and hence formed under a different climate regime. However, the recognition of these landslides is important because natural and human-induced factors can alter stability. Reduction of lateral support (by excavations or roadcuts), removal of vegetation (by fire or development), or an increase in pore pressure (by heavy rains) may result in the reactivation of landslides or parts of landslides.

Scientific Investigations Map↗