Simple procedural method for estimating on-site soil erosion

CER76-77DBS-RML-TJW38.Prepared for USDA Forest Service, Rocky Mountain Forest and Range Experiment Station.Includes bibliographical references (pages 37-38).February 1977

A New Look at Landslides of the Vermilion and Echo Cliffs, Northern Arizona

The Vermilion and Echo Cliffs form a nearly continuous escarpment more than 160 km long within the Colorado Plateau physiographic province of North America. The cliffs overlie the Marble Platform in northern Arizona and are located along the Colorado River, just upstream of the Grand Canyon. Large rotational block landslides mantle the erosional escarpment along most of its extent. Although these landslides have been noted for over 100 years, their likely origin has never been explained. Landslide failure surfaces appear to be influenced by the Petrified Forest Member of the Triassic Chinle Formation, a shale layer containing smectite clay weathered from volcanic ash. Although landslides are common along the majority of escarpments comprising the Colorado Plateau where the Petrified Forest Member and other shales outcrop, most appear to have been inactive since the early Holocene. Multiple generations of landslides and remnants of previous slides exist up to 3 km from the present cliff face. Multiple working hypotheses explaining these landslides are explored in this article, including past landslides and/or lava dams along the Colorado River within the Grand Canyon, periods of wetter climate with higher groundwater levels, and earthquakes related to nearby faulting and volcanism. Various sliding modes along these cliffs are described along with potential triggering mechanisms. Back-analysis of these landslides has been conducted using mechanical properties of the formations involved as well as varying groundwater levels. Calculated factors of safety for existing slides under present conditions are greater than unity, consistent with their apparent stability

Noxious weed survey and integrated noxious weed management plan: Schriever Air Force Base, El Paso County, CO

Prepared for: Schriever Air Force BaseMay 20173Includes bibliographical references

Native Legumes Versus Lespedeza cuneata: Implications for Ecosystem Services

Grasslands are the most threatened ecosystem worldwide due to habitat fragmentation and alteration, which have contributed to the spread of invasive plants. Fire is historically important in maintaining grasslands, and can reduce or eliminate some invasive plants, but facilitates the germination and spread of others. Invasive plants compete with natives and have the potential to impact ecosystem services (i.e., decomposition, soil C and N storage, pollination). Lespedeza cuneata is an invasive legume that reduces the abundance and diversity of native plants and can form monotypic stands. Many native legumes occur sympatrically with L. cuneata, including Lespedeza virginica and Baptisia bracteata. I evaluated if native versus invasive legume cover in different burn regimes influenced 1) litter decomposition and 2) invertebrate abundance and morphospecies richness, and if native versus invasive legume cover influenced 3) soil organic N (SON) and soil organic C (SOC), and 4) pollinator morphospecies richness and abundance. Sites were located within north-central Oklahoma in patch-burn managed rangelands. Findings suggest that decomposition and soil invertebrate morphospecies richness and abundance was highest in year of burn locations (versus two years since burn) and the highest level of L. cuneata cover. Decomposition was higher when microinvertebrates and macroinvertebrates were allowed access to litter, versus when only microinvertebrates were. SON and SOC (%) were positively correlated and lowest in areas with B. bracteata and increased as L. cuneata cover increased. Pollinator (Hymenoptera) richness was greater in locations with intermediate L. cuneata cover rather than in areas with more or less Lespedeza cover, including native Lespedeza cover. If abundance of decomposers and morphospecies richness of decomposers and pollinators is higher in locations dominated by L. cuneata, associated ecosystem services, including decomposition, soil C and N storage, and pollination, may contribute to its spread and the isolation of natives, further influencing grassland productivity and diversity. Additional research should evaluate these interactions with other invasive species and congeneric natives to identify factors that contribute to observed patterns across systems

Parent material-topographic-management controls on organic and inorganic nutrients in semiarid soils

1984 Fall.Covers not scanned.Includes bibliographical references.Print version deaccessioned 2023.Paired native grassland and cultivated landscapes were characterized to evaluate parent material and topographic controls on organic matter and phosphorus along catenary sequences in southwestern North Dakota. Site selection was based on parent material (sandstone, siltstone, and shale residuum), similar cropping history (44-yr wheat-fallow rotation), and uniform range management. Parent material-soil process relationships were established by evaluating chemical and physical data for soil profiles at the native-summit landscape segments on the three contrasting parent materials. The effects of topography on the amounts and vertical distribution of organic matter and phosphorus were evaluated by studying soil profiles at various geomorphic landscape components along the catenas. The effects of 44 years of cultivation were evaluated by comparing cultivated and virgin soils at each landscape segment using the soils on native pasture as benchmarks. The finer textured soils weathered in shale were found to have much higher levels of organic C, N and Total P. Soils weathered in sandstone were found to have more uniform decreases in organic matter with profile depth and the highest quantities of organic P. On the native pastures, quantities of organic matter were much higher in the lower landscape segments because of higher moisture contents and/or the deposition of organic matter-enriched soil. Soils at lower landscape segments (lower backslopes, footslopes) have been enriched with Total P at the expense of soils at the upper portions of the catenas. Changes in organic and inorganic soil constituents resulting from cultivation were found to vary as a function of parent material and topography. Mineralization losses of organic constituents appear to have been higher in the sandstone soils. The fine-textured shale soils, which appear to have a large proportion of highly humified, clay associated organic matter, lost the lowest quantities of organic constituents relative to total soil loss. Losses of organic matter were generally lower at the lower landscape segments in all three sites, reflecting soil deposition. Redistribution of soil material by both mechanical (tillage practices) and natural processes (wind and water erosion) must be considered when evaluating cultivation-induced changes in soil properties along catenary sequences

Las Vegas Wash and Lake Mead proposed water quality standards: Revisions and rationale

Rationale of review and for proposed changes to the Nevada Pollution Control Regulations (NAC 445.1354, 445.1355, 445.1356, 455.1367, 445.1352, 445.1353, 445.1350, 445.1351) before the State Environmental Commission on June 23 and 24, 1987