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At least 1,189 records · Page 66Linked to original sources
USGS1996

Uruguay Roselli 1938 and Rosellichnus, N. Ichnogenus: Two ichnogenera for clusters of fossil bee cells

The systematics of the fossil bee nest ichnogenus Uruguay from the Uruguayan Cretaceous or lower Tertiary is reviewed and two new ichnospecies of a new ichnogenus, Rosellichnus, are proposed for fossil bee nests from the Miocene of the United Arab Emirates and Patagonian Argentina. Uruguay contains U. auroranormae (the ich‐notype) and U. rivasi, which differs from the type ichnospecies in having clustered cells arranged in three rows, with one central and two marginal rows of subparallel cells. No bee nest architecture known to us unequivocally fits with any ichnospecies described herein. Uruguay was constructed in the subsoil and may be of halictid origin; however, its large cell size, thick cell walls, and the presence of a vestibular cell do not fit the architecture of nests of extant halictids. Rosellichnus arabicus lacks the complete cavity surrounding the cell cluster that is typical in nests of Old World halictids, but it may, nonetheless, still be of halictid origin. R. pa‐tagonicus has an architecture more similar to nests of anthophorine bees than to those of Neotropical Halictidae. Therefore, the ichnogenus Rosellichnus may include both halictid and anthophorine constructions. Although the smooth inner cell walls, spiral cell caps, and clustering of cells indicate that both Uruguay and Rosellichnus are trace fossils of bee origin, it is likely that both represent nest architectures that are no longer employed by extant bees, or those that are as yet unknown. The paleoenvironments of both the Argentine and Emirates species of Rosellichnus indicate that the trace‐makers of this ichnogenus constructed their nests in open ground sandy soils.

Ichnos: An International Journal for Plant and Ani↗
USGS2016

Insular ecosystems of the southeastern United States—A regional synthesis to support biodiversity conservation in a changing climate

In the southeastern United States, insular ecosystems—such as rock outcrops, depression wetlands, high-elevation balds, flood-scoured riparian corridors, and insular prairies and barrens—occupy a small fraction of land area but constitute an important source of regional and global biodiversity, including concentrations of rare and endemic plant taxa. Maintenance of this biodiversity depends upon regimes of abiotic stress and disturbance, incorporating factors such as soil surface temperature, widely fluctuating hydrologic conditions, fires, flood scouring, and episodic droughts that may be subject to alteration by climate change. Over several decades, numerous localized, site-level investigations have yielded important information about the floristics, physical environments, and ecological dynamics of these insular ecosystems; however, the literature from these investigations has generally remained fragmented. This report consists of literature syntheses for eight categories of insular ecosystems of the southeastern United States, concerning (1) physical geography, (2) ecological determinants of community structures including vegetation dynamics and regimes of abiotic stress and disturbance, (3) contributions to regional and global biodiversity, (4) historical and current anthropogenic threats and conservation approaches, and (5) key knowledge gaps relevant to conservation, particularly in terms of climate-change effects on biodiversity. This regional synthesis was undertaken to discern patterns across ecosystems, identify knowledge gaps, and lay the groundwork for future analyses of climate-change vulnerability. Findings from this synthesis indicate that, despite their importance to regional and global biodiversity, insular ecosystems of the southeastern United States have been subjected to a variety of direct and indirect human alterations. In many cases, important questions remain concerning key determinants of ecosystem function. In particular, few empirical investigations in these ecosystems have focused on possible climate-change effects, despite the well-documented ecological effects of climate change at a global level. Long-term management of these ecosystems could benefit from increased scientific effort to characterize and quantify the linkages between changing environmental conditions and the ecological processes that sustain biodiversity.

Alabama, Arkansas, Florida, Georgia, Kentucky, Lou↗
USGS2015

The continuing medical mystery of Balkan Endemic Nephropathy

Balkan Endemic Nephropathy (BEN) is a disease of subtle onset and insidious progression that typically occurs between the 4th and 6th decade in long‐resident individuals in highly specific geographic locations of the Balkan region and affects 1 – 5% of the population. Though it does not follow typical Mendelian genetics, there is a familial pattern of occurrence. Although residents may live only a few kilometers apart, certain locations are highly affected while others close by, even as close as across the road, remain unscathed. Because of this geographic selectivity scientists have searched for an environmental cause. It is thought that exposure to the toxic plant Aristolochia clematitis is to blame. Genotoxic N‐heterocyclic or polycyclic aromatic containing coal water leachates entering cultivated soil and drinking water are also a possible cause due to the proximity and predictive power of endemic foci to coal deposits. Evidence for Ochratoxin A fungal poisoning also exists. High levels of phthalates have been measured in BEN‐endemic drinking water. BEN is a probably a multifactorial disease that may result from exposure through some of above‐mentioned environmental sources, with genetic factors contributing. This review will discuss recent research concerning the etiology, potential therapies for the treatment of nephropathy, and unexplored research directions for this chronic kidney disease.

Journal of Rare Diseases↗
USGS2024

Preliminary ground and airborne-based geophysical mapping and modelling of an active hydrothermal system at Mammoth Lakes, California

Mammoth Lakes, California hosts a productive hydrothermal system within the seismically active south moat of Long Valley Caldera. Surficial evidence of the shallow hydrothermal system includes discrete zones of tree-kill dispersed between Shady Rest Park and the Casa Diablo Geothermal Power Plant (40 MW), as well as east of the power plant. The tree-kill areas are associated with elevated diffuse CO₂ emissions, heated ground, hydrothermal alteration, diffuse soil H₂S emissions, and gas vents. Previous mapping delineates prominent north and northwest trending structures within the south moat along the southwestern edge of the resurgent dome that may accommodate gas and fluid flow at the Shady Rest Park and Basalt Canyon Tree Kill Areas (SRTKA and BCTKA, respectively). Both tree-kill areas are also located along contacts between resurgent rhyolite, mafic lavas, and surficial deposits which may provide additional pathways for gas and fluid migration in the shallow subsurface. Characterizing structure and lithology using geophysical anomalies is critical to determining primary structural controls on the hydrothermal system and the extent of subsurface alteration at these sites. We conducted ground and airborne-based potential field geophysical surveys to map gravity and magnetic anomalies. These anomalies are then used to model subsurface geology, structure, and hydrothermal alteration. Here we present our preliminary geophysical mapping and modelling results at both tree-kill locations. Gravity and magnetic data suggest complex structural intersections are coincident with heated ground and gas emissions at the SRTKA and BCTKA. Hydrothermal systems are often observed or interpreted to exploit fault intersections which can serve as highly permeable pathways for hydrothermal fluid and gas discharge, enabling economic geothermal energy production. Geophysical mapping and modelling are an effective means of investigating such structural complexity at Mammoth Lakes due to the presence of unidentified and concealed structures.

California↗
USGS2012

Current and potential sustainable corn stover feedstock for biofuel production in the United States

Increased demand for corn ( Zea mays L.) stover as a feedstock for cellulosic ethanol raises concerns about agricultural sustainability. Excessive corn stover harvesting could have long-term impacts on soil quality. We estimated current and future stover production and evaluated the potential harvestable stover amount (HSA) that could be used for biofuel feedstock in the United States by defining the minimum stover requirement (MSR) associated with the current soil organic carbon (SOC) content, tillage practices, and crop rotation systems. Here we show that the magnitude of the current HSA is limited (31 Tg y −1 , dry matter) due to the high MSR for maintaining the current SOC content levels of soils that have a high carbon content. An alternative definition of MSR for soils with a moderate level of SOC content could significantly elevate the annual HSA to 68.7 Tg, or even to 132.2 Tg if the amount of currently applied manure is counted to partially offset the MSR. In the future, a greater potential for stover feedstock could come from an increase in stover yield, areal harvest index, and/or the total planted area. These results suggest that further field experiments on MSR should be designed to identify differences in MSR magnitude between maintaining SOC content and preventing soil erosion, and to understand the role of current SOC content level in determining MSR from soils with a wide range of carbon contents and climatic conditions.

Biomass and Bioenergy↗
USGS2002

Pathways of nutrient loading and impacts on plant diversity in a New York peatland

Nutrient loading is a subtle, yet serious threat to the preservation of high diversity wetlands such as peatlands. Pathways of nutrient loading and impacts on plant diversity in a small peatland in New York State, USA were determined by collecting and analyzing a suite of hydrogeological, hydro-chemical, soil, and vegetation data. Piezometer clusters within an intensive network constituted hydro-chemical sampling points and focal points for randomly selected vegetation quadrats and soil-coring locations. Hydrogeological data and nutrient analyses showed that P and K loading occurred chiefly by means of overland flow from an adjacent farm field, whereas N loading occurred predominantly through ground-water flow from the farm field. Redundancy analysis and polynomial regression showed that nutrients, particularly total P in peat, total K in peat, extractable NH 4 -N, and NO 3 -N flux in ground water, were strongly negatively correlated with plant diversity measures at the site. No other environmental variables except vegetation measures associated with eutrophication demonstrated such a strong relationship with plant diversity. Nitrate loading over 4 mg m −2 day −1 was associated with low plant diversity, and Ca fluxes between 80 and 130 mg m −2 day −1 were associated with high plant diversity. Areas in the site with particularly low vascular plant and bryophyte species richness and Shannon-Wiener diversity (H′) occurred adjacent to the farm field and near a hillside spring. High H′ and species richness of vascular plants and bryophytes occurred in areas that were further removed from agriculture, contained no highly dominant vegetation, and were situated directly along the ground-water flow paths of springs. These areas were characterized by relatively constant water levels and consistent, yet moderate fluxes of base cations and nutrients. Overall, this study demonstrates that knowledge of site hydrogeology is crucial for determining potential pathways of nutrient loading and for developing relationships between nutrient inflows and wetland plant diversity.

New York↗
USGS2020

Weed-suppressive bacteria have no effect on exotic or native plants in sagebrush-steppe

Approaches and techniques for control of exotic annual grasses are a high priority in rangelands including sagebrush steppe. Strains of the soil bacterium Pseudomonas fluorescens have been proposed to be selectively pathogenic to multiple species of exotic annual grasses (“Pf,” weed-suppressive bacteria, “WSB”). However, defensible tests of the target and nontarget effects of these WSB strains in the field are needed. We evaluated the effects of D7 and MB906 strains of Pf WSB in sagebrush steppe invaded by cheatgrass ( Bromus tectorum L), medusahead ( Taeniatherum caput-medusae L. Nevski), and other exotic annual grasses. We evaluated the WSB strains with and without herbicides (imazapic, rimsulfuron) or discing to mix surface-spray of the WSB into deeper soils, and we replicated these tests in three ecoregions that differed in soils and climate. Over 3 yr after treatment, neither WSB strain affected cover of exotic annual grasses, perennial bunchgrasses, or the total community, either with WSB alone or in combination with herbicides or discing. WSB has received considerable attention and is being applied across large rangeland areas, but the WSB strains and methods applied here were ineffective. We recommend any future use of WSB be applied in an experimental fashion, with experimental design and measurement of responses, until its effects can be proven.

Rangeland Ecology & Management↗
USGS1993

Element concentrations in growth rings of trees near an abandoned wood-preserving plant site at Jackson, Tennessee

Multielement analysis was performed on individual annual rings of trees growing at and near an abandoned wood-preserving plant site in Jackson, Tennessee, that operated from the early 1930's until 1981. Numerous organic compounds associated with the wood-preserving process have been detected in soils, ground water, and surface water within much of the site. Tree-ring investigations were conducted prior to investigations of ground water downgradient from the site to determine if trees preserved an areal and temporal record of contaminant movement into offsite areas. Increment cores were collected from trees on the abandoned plant site, in downgradient areas west and south of the site, and at two locations presumably unaffected by contamination from the site. Multielement analysis by proton-induced X-ray emission was performed on 5 to 15 individual growth rings from each of 34 trees that ranged in age from about 5 to 50 years. Concentrations of 16 elements were evaluated by analyzing average concentrations within the 1987, 1989, and 1990 rings of all trees; analyzing element-concentration trends along entire core radii; and analyzing element correlations between and among trees. Concentrations of some nutrients and trace metals were elevated in the outermost sapwood rings of some trees that grow south and southwest of the most contaminated part of the site; small trees on the main part of the site and larger trees to the west generally contained fewer rings with elevated concentrations, particularly of trace metals. Concentrations of several elements elevated in tree rings also were elevated in water samples collected from the reach of a stream that flows near the southwestern part of the site. Multielement analysis of each ring of a willow growing along the southern boundary of the site detected extremely large concentrations of chromium, nickel, and iron in rings that formed in 1986 and thereafter. Relative increases in the concentrations of these elements also were detected in a silver maple growing next to the willow, but not in another silver maple growing 150 meters farther to the west. An oak growing in the southwestern part of the study area contained large concentrations of calcium and several trace elements, and some trees south of the abandoned site contained large concentrations of phosphorus or potassium. Concentrations of trace metals and nutrients in some trees may be related to wood-preserving activities at the site and possibly to remedial efforts conducted during the early to mid 1980's.However, the possibility cannot be discounted that large concentrations of some elements are from sources other than the wood-preserving facility, or in part from flooding of the South Fork Forked Deer River.

Water-Resources Investigations Report↗
USGS1997

Decomposition of saltmeadow cordgrass (Spartina patens) in Louisiana coastal marshes

In Louisiana, plant production rates and associated decomposition rates may be important in offsetting high rates of land loss and subsidence in organic marsh soils. Decomposition of Spartina patens shoot and leaf material was studied by using litter bags in mesohaline marshes in the Barataria and Terrebonne basins of coastal Louisiana. Spartina patens decomposed very slowly with an average decay constant of 0.0007, and approximately 50% of the material remained after 2 years in the field. Material at the Barataria site decomposed faster than did Terrebonne material with trend differences apparent during the first 150 days. This difference might be explained by the higher content of phosphorus in the Barataria material or a flooding period experienced by the Barataria bags during their first 10 days of deployment. Nitrogen and carbon content of the plant material studied did not differ between the two basins. We detected no consistent significant differences in decomposition above, at, or below sediment/water level. Because S. patens is the dominant plant in these marshes, and because it is so slow to decompose, we believe that S. patens shoots are an important addition to vertical accretion and, therefore, marsh elevation.

Louisiana↗
USGS2013

Characterization of water quality and biological communities, Fish Creek, Teton County, Wyoming, 2007-2011

Fish Creek, an approximately 25-kilometer-long tributary to Snake River, is located in Teton County in western Wyoming near the town of Wilson. Fish Creek is an important water body because it is used for irrigation, fishing, and recreation and adds scenic value to the Jackson Hole properties it runs through. Public concern about nuisance growths of aquatic plants in Fish Creek has been increasing since the early 2000s. To address these concerns, the U.S. Geological Survey conducted a study in cooperation with the Teton Conservation District to characterize the hydrology, water quality, and biologic communities of Fish Creek during 2007–11. The hydrology of Fish Creek is strongly affected by groundwater contributions from the area known as the Snake River west bank, which lies east of Fish Creek and west of Snake River. Because of this continuous groundwater discharge to the creek, land-use activities in the west bank area can affect the groundwater quality. Evaluation of nitrate isotopes and dissolved-nitrate concentrations in groundwater during the study indicated that nitrate was entering Fish Creek from groundwater, and that the source of nitrate was commonly a septic/sewage effluent or manure source, or multiple sources, potentially including artificial nitrogen fertilizers, natural soil organic matter, and mixtures of sources. Concentrations of dissolved nitrate and orthophosphate, which are key nutrients for growth of aquatic plants, generally were low in Fish Creek and occasionally were less than reporting levels (not detected). One potential reason for the low nutrient concentrations is that nutrients were being consumed by aquatic plant life that increases during the summer growing season, as a result of the seasonal increase in temperature and larger number of daylight hours. Several aspects of Fish Creek’s hydrology contribute to higher productivity and biovolume of aquatic plants in Fish Creek than typically observed in streams of its size in Wyoming. Especially in the winter, the proportionately large, continuous gain of groundwater into Fish Creek in the perennial section keeps most of the creek free of ice. Because sunlight can still reach the streambed in Fish Creek and the water is still flowing, aquatic plants continue to photosynthesize in the winter, albeit at a lower level of productivity. Additionally, the cobble and large gravel substrate in Fish Creek provides excellent attachment points for aquatic plants, and when combined with Fish Creek’s channel stability allows rapid growth of aquatic plants once conditions allow during the spring. The aquatic plant community of Fish Creek was different than most streams in Wyoming in that it contains many different macrophytes—including macroalgae such as long streamers of Cladophora , aquatic vascular plants, and moss; most other streams in the state contain predominantly algae. From the banks of Fish Creek, the bottom of the stream sometimes appeared to be a solid green carpet. A shift was observed from higher amounts of microalgae in April/May to higher amounts macrophytes in August and October, and differences in the relative abundance of microalgae and macrophytes were statistically significant between seasons. Differences in dissolved-nitrate concentrations and in the nitrogen-to-phosphorus ratio were significantly different between seasons, as concentrations of dissolved nitrate decreased from April/May to August and October. It is likely that dissolved-nitrate concentrations in Fish Creek were lower in August and October because macrophytes were quickly utilizing the nutrient, and a negative correlation between macro-phytes and nitrate was found. Macroinvertebrates also were sampled because of their role as indicators of water quality and their documented responses to perturbation such as degradation of water quality and habitat. Statistically significant seasonal differences were noted in the macroinvertebrate community. Taxa richness and relative abundance of Ephemeroptera, Plecoptera, and Trichoptera, which tend to be intolerant of water-quality degradation, decreased from April/May to August; the same time period saw a corresponding increase in Diptera and noninsects, particularly Oligochaeta (worms) that are more tolerant. Seasonal changes in macroinvertebrate functional feeding groups were significantly different. The relative abundance of gatherer-collector and scraper feeding groups decreased from April/May to August, accompanied by an increase in filterer-collector and shredders feeding groups. Seasonal changes in feeding groups might be due to the seasonal shift in aquatic plant communities, as indicated by comparison with other streams in the area that had fewer aquatic macrophytes than Fish Creek. Statistical tests of macroinvertebrate metrics indicated few differences between years or biological sampling sites on Fish Creek, although the site farthest upstream sometimes was different not only in terms of macroinvertebrates but also in streamflow, water quality, and aquatic plants. Potential effects of contributions of additional nutrients to the Fish Creek ecosystem beyond the conditions sampled during the study period are not known. However, because virtually all of the detectable dissolved nitrate commonly was consumed by aquatic plants in August (leaving dissolved nitrate less than the reporting level in water samples), it is possible that increased nutrient contributions could cause increased growth of aquatic plants. Additional long-term monitoring of the stream, with concurrent data analysis and interpretation would be needed to determine the effects of additional nutrients on the aquatic plant community and on higher levels of the food chain.

Wyoming↗
USGS2016

Vegetation of semi-stable rangeland dunes of the Navajo Nation, Southwestern USA

Dune destabilization and increased mobility is a worldwide issue causing ecological, economic, and health problems for the inhabitants of areas with extensive dune fields. Dunes cover nearly a third of the Navajo Nation within the Colorado Plateau of southwestern USA. There, higher temperatures and prolonged drought beginning in 1996 have produced significant increases in dune mobility. Vegetation plays an important role in dune stabilization, but there are few studies of the plants of the aeolian surfaces of this region. We examined plant species and their attributes within a moderately vegetated dune field of the Navajo Nation to understand the types and characteristics of plants that stabilize rangeland dunes. These dunes supported a low cover of mixed grass-scrubland with fifty-two perennial and annual species including extensive occurrence of non-native annual Salsola spp. Perennial grass richness and shrub cover were positively associated with increased soil sand composition. Taprooted shrubs were more common on sandier substrates. Most dominant grasses had C4 photosynthesis, suggestive of higher water-use efficiencies and growth advantage in warm arid environments. Plant cover was commonly below the threshold of dune stabilization. Increasing sand movement with continued aridity will select for plants adapted to burial, deflation, and abrasion. The study indicates plants tolerant of increased sand mobility and burial but more investigation is needed to identify the plants adapted to establish and regenerate under these conditions. In addition, the role of Salsola spp. in promoting decline of perennial grasses and shrubs needs clarification.

Arizona, Colorado, New Mexico, Utah↗
USGS2019

Landscape and organismal factors affecting sagebrush-seedling transplant survival after megafire restoration

Larger and more frequent disturbances are motivating efforts to accelerate recovery of foundational perennial species by focusing efforts into establishing island patches to sustain keystone species and facilitate recovery of the surrounding plant community. Evaluating the variability in abiotic and biotic factors that contribute to differences in survival and establishment can provide useful insight into the relative importance of these factors. In the western United States, severe degradation of the sagebrush steppe has motivated substantial efforts to restore native perennial cover, but success has been mixed. In this study, we evaluated survival of >3000 sagebrush seedlings transplanted on 12 patches totaling of 650 ha within a 113,000 ha burn area, and related the survival to organismal and sub‐taxonomic traits, and to landscape variables. Big sagebrush has high intraspecific diversity attributed to subspecies and cytotypes identifiable through UV‐induced fluorescence, length:width of leaves, or genome size (ploidy). Of these organismal traits, survival was related only to UV fluorescence, and then only so when landscape variables were excluded from analyses. The most significant landscape variable affecting survival was soil taxonomic subgroup, with much lower survival where buried restrictive layers reduce deep water infiltration. Survival also decreased with greater slope steepness, exotic annual grass cover, and burn severity. Survival was optimal where perennial bunchgrasses comprised 8‐14% of total cover. These soil, topographic, and community condition factors revealed through monitoring of landscape‐level treatments can be used to explain the success of plantings and to strategically plan future restoration projects.

Restoration Ecology↗
USGS2009

Fire rehabilitation effectiveness: a chronosequence approach for the Great Basin

Federal land management agencies have invested heavily in seeding vegetation for emergency stabilization and rehabilitation (ES&R) of non-forested lands. ES&R projects are implemented to reduce post-fire dominance of non-native annual grasses, minimize probability of recurrent fire, quickly recover lost habitat for sensitive species, and ultimately result in plant communities with desirable characteristics including resistance to invasive species and resilience or ability to recover following disturbance. Land managers lack scientific evidence to verify whether seeding non-forested lands achieves their desired long-term ES&R objectives. The overall objective of our investigation is to determine if ES&R projects increase perennial plant cover, improve community composition, decrease invasive annual plant cover and result in a more desirable fuel structure relative to no treatment following fires while potentially providing habitat for Greater Sage-Grouse, a species of management concern. In addition, we provide the locations and baseline vegetation data for further studies relating to ES&R project impacts. We examined effects of seeding treatments (drill and broadcast) vs. no seeding on biotic and abiotic (bare ground and litter) variables for the dominant climate regimes and ecological types within the Great Basin. We attempted to determine seeding effectiveness to provide desired plant species cover while restricting non-native annual grass cover relative to post-treatment precipitation, post-treatment grazing level and time-since-seeding. Seedings were randomly sampled from all known post-fire seedings that occurred in the four-state area of Idaho, Nevada, Oregon and Utah. Sampling locations were stratified by major land resource area, precipitation, and loam-dominated soils to ensure an adequate spread of locations to provide inference of our findings to similar lands throughout the Great Basin. Nearly 100 sites were located that contained an ES&R project. Of these sites, 61 were seeded by using a drill, 27 were broadcast aerially, and 12 had a combination of both. We randomly sampled three burned and seeded, burned and unseeded, and unburned and unseeded locations in the vicinity of the fire, each within the same ecological site. We measured foliar cover of all plant functional groups (perennial or annual, shrub, grass, forb, native or introduced), biological soil crusts, and abiotic (bare soil and litter) variables using the line-point intercept protocol. Fuel loads and horizontal fuel continuity were measured. We applied linear mixed models to response variables (cover and density of plant groups) relative to the dependent variables (seeding treatments and precipitation/temperature relationships. Post-fire strengths with native perennial grasses or shrubs in mixes did not increase density or cover of these groups significantly relative to unseeded, burned areas. Seeded non-native perennial grasses and the shrub Bassia prostrata were effective in providing more cover in aerial and drill seedings. Seeded non-native perennial grass cover increased with increased annual precipitation regardless of seeding type. Seeding native shrubs, particularly Artemisia tridentata, did not significantly increase shrub cover in burned areas. Cover of undesirable non-native annual grasses was lower in drill seedings relative to unseeded areas but only at higher elevations. Seeding effectiveness after wildfire is unpredictable in drier, low elevation environments, and our findings indicate management objectives are more likely met when focusing efforts on higher elevation or higher precipitation locations where establishment of perennial grasses is more likely. On sites where potential for invasion and dominance of non-native annuals is high, such as lower and drier sites, intensive methods of restoration that include invasive plant control before seeding may be required. Where establishment of native perennial plants is the goal, managers might consider using native-only seed mixtures, because we found that the non-native perennials typically used in Great Basin restoration efforts are selected for their competitive nature and may reduce establishment of less competitive native species. Although we attempted to include information on livestock grazing history after seedings, we were unable to extract sufficient data from files to address this topic that may play an additional role in understanding native plant abundance post-fire seeding. Evaluation of drill and aerial seeding effects on fuel characteristics focused on two metrics that are standard inputs for fire behavior models, fuel load and fuel continuity. Fuel loads were evaluated separately for total fuel load biomass, and the individual components that sum to total biomass, namely herbaceous, shrub, shrub:herbaceous ratio, litter, 10-hour, and 100-hour fuel biomasses. Fuel continuity was evaluated using the following cover categories, total, annual grass, annual forb, perennial forb perennial grass, shrub, litter, vegetative interspace, and perennial interspace. Drill seeding did not affect fuel loads, except to reduce 10-hour fuels, probably due to mechanical destruction of dead and down fuels by the drill seeding equipment. Drill seeding did affect fuel continuity, specifically decreasing total plant cover by increasing perennial grass cover which suppressed annual grass and litter production resulting in a net decrease in continuity, but only at the elevations above approximately 1500m. Aerial seeding had no effect on any fuel load or fuel continuity category. For the Greater Sage-Grouse habitat study, we developed multi-scale empirical models of sage-grouse occupancy in 211 randomly located plots within a 40 million ha portion of the species’ range. We then used these models to predict sage-grouse habitat quality at 101 ES&R seeding projects. We compared conditions at restoration sites to published habitat guidelines. Sage-grouse occupancy was positively related to plot- and landscape-level dwarf sagebrush (Artemisia arbuscula, A. nova, A. tripartita) and big sagebrush steppe, and negatively associated with non-native grass and human development. The predicted probability of sage-grouse occupancy at treated plots was low on average (0.07–0.09) and was not significantly different from burned areas that had not been treated. Restoration was more often successful at higher elevation sites with low annual temperatures, high spring precipitation, and high plant diversity. No plots seeded after fire (n=313) met all overstory guidelines for breeding habitats, but approximately 50% met understory guidelines, particularly for perennial grasses. This trend was similar for summer habitat. Ninety-eight percent of treated plots did not meet winter habitat guidelines. Restoration actions in burned areas did not increase the probability of meeting most guideline criteria. The probability of meeting guidelines was influenced by a latitudinal gradient, local climate, and topography. Post-fire seeding treatments in Great Basin sagebrush shrublands generally have not created high quality habitat for sage-grouse. Understory conditions are more likely to be adequate than those of overstory, but in unfavorable climates, establishing forbs and reducing cheatgrass dominance is unlikely. Reestablishing sagebrush cover will require more than 20 years using the restoration methods of the past two decades. Given current fire frequencies and restoration capabilities, protection of landscapes containing a mix of dwarf sagebrush and big sagebrush steppe, minimal human development, and low non-native plant cover may provide the best opportunity for conservation of sage-grouse habitats. Our database of ES&R locations has used the Land Treatment Digital Library to archive data and location information regarding our study (see Pilliod and Welty 2013). This has contributed to two additional studies. One examined the potential spread of Bassia prostrata (aka Kochia prostrata; forage kochia) from ES&R project locations (Gray and Muir 2013). The second used remote sensing to determine the phenology of vegetation green-up on post-fire seeded sites (Sankey et al. 2013).

California;Idaho;Oregon;Utah↗
USGS2014

Human infrastructure and invasive plant occurrence across rangelands of southwestern Wyoming, U.S.A.

Although human influence across rural landscapes is often discussed, interactions between the native, natural systems and human activities are challenging to measure explicitly. We assessed the distribution of introduced, invasive species as related to anthropogenic infrastructure and environmental conditions across southwestern Wyoming. to discern direct correlations as well as covariate influences between land use, land cover, and abundance of invasive plants, and assess the supposition that these features affect surrounding rangeland conditions. Our sample units were 1 000 m long and extended outward from target features, which included roads, oil and gas well pads, pipelines, power lines, and featureless background sites. Sample sites were distributed across the region using a stratified, random design with a frame that represented features and land-use intensity. In addition to land-use gradients, we captured a representative, but limited, range of variability in climate, soils, geology, topography, and dominant vegetation. Several of these variables proved significant, in conjunction with distance from anthropogenic features, in regression models of invasive plant abundance. We used general linear models to demonstrate and compare associations between invasive plant frequency and Euclidian distance from features, natural logarithm transformed distances (log-linear), and environmental variables which were presented as potential covariates. We expected a steep curvilinear (log or exponential) decline trending towards an asymptote along the axis representing high abundance near features with rapid decrease beyond approximately 50–100 m. Some of the associations we document exhibit this pattern, but we also found some invasive plant distributions that extended beyond our expectations, suggesting a broader distribution than anticipated. Our results provide details that can inform local efforts for management and control of invasive species, and they provide evidence of the different associations between natural patterns and human land use exhibited by nonnative species in this rural setting, such as the indirect effects of humans beyond impact areas.

Wyoming↗
USGS2018

A remote sensing-based model of tidal marsh aboveground carbon stocks for the conterminous United States

Remote sensing based maps of tidal marshes, both of their extents and carbon stocks, have the potential to play a key role in conducting greenhouse gas inventories and implementing climate mitigation policies. Our objective was to generate a single remote sensing model of tidal marsh aboveground biomass and carbon that represents nationally diverse tidal marshes within the conterminous United States (CONUS). We developed the first calibration-grade, national-scale dataset of aboveground tidal marsh biomass, species composition, and aboveground plant carbon content (%C) from six CONUS regions: Cape Cod, MA, Chesapeake Bay, MD, Everglades, FL, Mississippi Delta, LA, San Francisco Bay, CA, and Puget Sound, WA. Using the random forest machine learning algorithm, we tested whether imagery from multiple sensors, Sentinel-1 C-band synthetic aperture radar, Landsat, and the National Agriculture Imagery Program (NAIP), can improve model performance. The final model, driven by six Landsat vegetation indices and with the soil adjusted vegetation index as the most important (n = 409, RMSE = 310 g/m 2 , 10.3% normalized RMSE), successfully predicted biomass for a range of marsh plant functional types defined by height, leaf angle and growth form. Model results were improved by scaling field-measured biomass calibration data by NAIP-derived 30 m fraction green vegetation. With a mean plant carbon content of 44.1% (n = 1384, 95% C.I. = 43.99%–44.37%), we generated regional 30 m aboveground carbon density maps for estuarine and palustrine emergent tidal marshes as indicated by a modified NOAA Coastal Change Analysis Program map. We applied a multivariate delta method to calculate uncertainties in regional carbon densities and stocks that considered standard error in map area, mean biomass and mean %C. Louisiana palustrine emergent marshes had the highest C density (2.67 ± 0.004 Mg/ha) of all regions, while San Francisco Bay brackish/saline marshes had the highest C density of all estuarine emergent marshes (2.03 ± 0.004 Mg/ha). Estimated C stocks for predefined jurisdictional areas ranged from 1023 ± 39 Mg in the Nisqually National Wildlife Refuge in Washington to 507,761 ± 14,822 Mg in the Terrebonne and St. Mary Parishes in Louisiana. This modeling and data synthesis effort will allow for aboveground C stocks in tidal marshes to be included in the coastal wetland section of the U.S. National Greenhouse Gas Inventory. With the increased availability of free post-processed satellite data, we provide a tractable means of modeling tidal marsh aboveground biomass and carbon at the global extent as well.

ISPRS Journal of Photogrammetry and Remote Sensing↗
USGS1977

Quality of rivers of the United States, 1975 water year; based on the National Stream Quality Accounting Network (NASQAN)

The National Stream Quality Accounting Network (NASQAN) was established by the U.S. Geological Survey to provide a nationally uniform basis for continuously assessing the quality of U.S. rivers. Stations generally are at the downstream end of hydrologic accounting units in order to measure the quantity and quality of water flowing from the units. The 1975 water year was the first year of operation of the network that represents essentially all of the accounting units and thereby describes the water- quality of the entire country. Data are available on a large number of water-quality constituents measured at 345 stations during the 1975 water year. Temperature data (usually continuous or daily measurements) from NASQAN stations were fitted to a first order harmonic equation and the parameters for the harmonic function are reported for each station. Mean temperatures generally range from 5°-10°C in the North to more than 20°C along the southern border of the continental United States and in Hawaii and Puerto Rico; means were less than 10°C at 63 stations and greater than 25°C at only 7 stations. Amplitudes of the temperature curves are greatest (greater than 12°C) for the streams at midlatitudes and in the Great and Central Plains, and they are smallest for the subtropical and cold-climate streams. Considering chemical and biological characteristics of U.S. streams as described by NASQAN data, water quality is best (by many standards) in the Northeast, Southeast, and Northwest. Waters there generally are low in dissolved solids and major and minor chemical constituents, generally are soft (except in Florida), and carry relatively small amounts of sediment. These conditions mainly reflect the geology of the regions and the relatively large amounts of precipitation. However, many of these waters show the effects of pollution and carry moderate or high levels of major nutrients and have correspondingly high populations of attached and floating plants. High counts of indicator bacteria also show signs of local pollution, particularly in regions of the country with large human and animal populations. In the Northeast, some heavy metals are at moderate levels, but not above most water-quality criteria. Rivers of most of the Mid-Continent and Southwest reflect the arid or semi-arid climate, erodible soils, and agricultural activities. They are characterized by moderate to high levels of dissolved major and minor constituents, sediment, major nutrients, and biota (floating and attached aquatic plants and indicator bacteria). In addition, the most incidences of pesticides in stream and bottom sediments were found in these regions. A special analysis was made to study the patterns of dissolved solids, major nutrients, phytoplankton, and zinc in the Mississippi River above Memphis, Tennessee. It was found that flow volume is an important factor in influencing river quality, and that stations with low concentration of major nutrients generally had low phytoplankton populations as well.

Open-File Report↗
USGS2016

Mediterranean biomes: Evolution of their vegetation, floras and climate

Mediterranean-type ecosystems (MTEs) possess the highest levels of plant species richness in the world outside of the wet tropics. Sclerophyll vegetation similar to today’s mediterranean-type shrublands was already present on oligotrophic soils in the wet and humid climate of the Cretaceous, with fire-adapted Paleogene lineages in southwestern Australia and the Cape Region. The novel MTC seasonality present since the mid-Miocene has allowed colonization of MTEs from a regional species pool with associated diversification. Fire persistence has been a primary driving factor for speciation in four of the five regions. Understanding the regional patterns of plant species diversity among the MTEs involves complex interactions of geologic and climatic histories for each region as well as ecological factors that have promoted diversification in the Neogene and Quaternary. A critical element of species richness for many MTE lineages has been their ability to speciate and persist at fine spatial scales, with low rates of extinction.

Annual Review of Ecology, Evolution, and Systemati↗
USGS2019

Adaptive management assists reintroduction as higher tides threaten an endangered salt marsh plant

In theory, extirpated plant species can be reintroduced and managed to restore sustainable populations. However, few reintroduced plants are known to persist for more than a few years. Our adaptive‐management case study illustrates how we restored the endangered hemiparasitic annual plant, Chloropyron maritimum subsp. maritimum (salt marsh bird's beak), to Sweetwater Marsh, San Diego Bay National Wildlife Refuge, California, United States, and used monitoring and experimentation to identify the factors limiting the reintroduced population. After extirpation in 1988, reintroduction starting that year led to a resilient, genetically diverse population in 2016 (a “boom” of approximately 14,000) that rebounded from a “bust” (62 in 2014). Multiple regressions attributed 82% of the variation in population counts to tidal amplitude, rainfall, and temperature. Populations of salt marsh bird's beak crashed when the diurnal tide range peaked during the 18.6‐year lunar nodal cycle (a rarely considered factor that periodically added approximately 12 cm to tidal ranges). We explain booms as follows: During smaller tidal amplitudes , above‐average rainfall could desalinize upper intertidal soils and stimulate salt marsh bird's beak germination. Then, moderate temperature in May favors growth to reproduction in June. In addition, salt marsh bird's beak needs a short and open canopy of native perennial plants, with roots to parasitize (not non‐native annual grass pseudohosts) and nearby upland soil for a preferred pollinator, ground‐burrowing bees. Although our reintroduced salt marsh bird's beak population is an exceptional case of persistence, this rare species‐specific environmental and biological requirement makes it vulnerable to rising sea levels and global warming.

California↗