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At least 415 records · Page 23Linked to original sources
USGS2000

The use of fuel breaks in landscape fire management

Shaded fuelbreaks and larger landscape fuel treatments, such as prescribed fire, are receiving renewed interest as forest protection strategies in the western United States. The effectiveness of fuelbreaks remains a subject of debate because of differing fuelbreak objectives, prescriptions for creation and maintenance, and their placement in landscapes with differing fire regimes. A well-designed fuelbreak will alter the behavior of wildland fire entering the fuel-altered zone. Both surface and crown fire behavior may be reduced. Shaded fuelbreaks must be created in the context of the landscape within which they are placed. No absolute standards for fuelbreak width or fuel reduction are possible, although recent proposals for forested fuelbreaks suggest 400 m wide bands where surface fuels are reduced and crown fuels are thinned. Landscape-level treatments such as prescribed fire can use shaded fuelbreaks as anchor points, and extend the zone of altered fire behavior to larger proportions of the landscape. Coupling fuelbreaks with area-wide fuel treatments can reduce the size, intensity, and effects of wildland fires.

Forest Ecology and Management↗
USGS2024

Homogenization of soil seed bank communities by fire and invasive species in the Mojave Desert

Soil seed banks help maintain species diversity through temporal storage effects and function as germination pools that can optimize fitness across varying environmental conditions. These characteristics promote the persistence of native plant communities, yet disturbances such as fire and associated invasions by non-native species can disrupt these reserves, fundamentally altering successional trajectories. This may be particularly true in deserts, where native plant communities are less adapted to fire. While studies of fire effects on desert plant communities are not uncommon, information regarding the short- and long-term effects of fire on seed banks is less available. To better understand the influence of fire and invasive species on desert seed banks, we investigated soil seed bank biodiversity from 30 wildfires that burned between 1972 and 2010 across the Mojave Desert ecoregion of North America. We assessed how characteristics of fire regimes (frequency, time since fire, and burn severity) interacted with climate and invasive plants on measures of α-, β-, and γ-diversities. Because β-diversity is a direct measure of community variability and reveals important information about biodiversity loss, we further examined the nestedness and turnover components of β-diversity. Mean α- and γ-diversities were generally higher for burned locations than in unburned reference sites, however individual fire variables had little influence on patterns of seed bank diversity. Burned area seed banks tended to be dominated by non-native invasive species, primarily two grasses, ( Bromus rubens , Bromus tectorum ), as well as an invasive forb ( Erodium cicutarium ). The most striking pattern we observed was a collective sharp decline in α-, β-, and γ-diversities with increased invasive species dominance, indicating the homogenization of seed bank communities with the colonization of invasive species after fire. Evidence of homogenization was further supported by reduced turnover and increased nestedness in burn areas compared to reference areas indicating potential biodiversity loss. Our findings highlight how biological processes such as plant invasions can combine with disturbance from fire to alter patterns of seed bank composition and diversity in desert ecosystems.

Frontiers in Ecology and Evolution↗
USGS2013

Vegetation inventory, mapping, and classification report, Fort Bowie National Historic Site

A vegetation mapping and characterization effort was conducted at Fort Bowie National Historic Site in 2008-10 by the Sonoran Desert Network office in collaboration with researchers from the Office of Arid lands studies, Remote Sensing Center at the University of Arizona. This vegetation mapping effort was completed under the National Park Service Vegetation Inventory program which aims to complete baseline mapping inventories at over 270 national park units. The vegetation map data was collected to provide park managers with a digital map product that met national standards of spatial and thematic accuracy, while also placing the vegetation into a regional and even national context. Work comprised of three major field phases 1) concurrent field-based classification data collection and mapping (map unit delineation), 2) development of vegetation community types at the National Vegetation Classification alliance or association level and 3) map accuracy assessment. Phase 1 was completed in late 2008 and early 2009. Community type descriptions were drafted to meet the then-current hierarchy (version 1) of the National Vegetation Classification System (NVCS) and these were applied to each of the mapped areas. This classification was developed from both plot level data and censused polygon data (map units) as this project was conducted as a concurrent mapping and classification effort. The third stage of accuracy assessment completed in the fall of 2010 consisted of a complete census of each map unit and was conducted almost entirely by park staff. Following accuracy assessment the map was amended where needed and final products were developed including this report, a digital map and full vegetation descriptions. Fort Bowie National Historic Site covers only 1000 acres yet has a relatively complex landscape, topography and geology. A total of 16 distinct communities were described and mapped at Fort Bowie NHS. These ranged from lush riparian woodlands lining the ephemeral washes dominated by Ash (Fraxinus), Walnut (Juglans) and Hackberry (Celtis) to drier upland sites typical of desert scrub and semi-desert grassland communities. These shrublands boast a diverse mixture of shrubs, succulents and perennial grasses. In many places the vegetation could be seen to echo the history of the fort site, with management of shrub encroachment apparent in the grasslands and the paucity of trees evidence of historic cutting for timber and fire wood. Seven of the 16 vegetation types were ‘accepted’ types within the NVC while the others have been described here as specific to FOBO and have proposed status within the NVC. The map was designed to facilitate ecologically-based natural resources management and research. The map is in digital format within a geodatabase structure that allows for complex relationships to be established between spatial and tabular data, and makes accessing the product easy and seamless. The GIS format allows user flexibility and will also enable updates to be made as new information becomes available (such as revised NVC codes or vegetation type names) or in the event of major disturbance events that could impact the vegetation.

Arizona↗
USGS2016

Wildfire risk as a socioecological pathology

Wildfire risk in temperate forests has become a nearly intractable problem that can be characterized as a socioecological “pathology”: that is, a set of complex and problematic interactions among social and ecological systems across multiple spatial and temporal scales. Assessments of wildfire risk could benefit from recognizing and accounting for these interactions in terms of socioecological systems, also known as coupled natural and human systems (CNHS). We characterize the primary social and ecological dimensions of the wildfire risk pathology, paying particular attention to the governance system around wildfire risk, and suggest strategies to mitigate the pathology through innovative planning approaches, analytical tools, and policies. We caution that even with a clear understanding of the problem and possible solutions, the system by which human actors govern fire-prone forests may evolve incrementally in imperfect ways and can be expected to resist change even as we learn better ways to manage CNHS.

Frontiers in Ecology and the Environment↗
USGS2022

Natural and anthropogenic landscape factors shape functional connectivity of an ecological specialist in urban Southern California

Identifying how natural (i.e., unaltered by human activity) and anthropogenic landscape variables influence contemporary functional connectivity in terrestrial organisms can elucidate the genetic consequences of environmental change. We examine population genetic structure and functional connectivity among populations of a declining species, the Blainville's horned lizard ( Phrynosoma blainvillii ), in the urbanized landscape of the Greater Los Angeles Area in Southern California, USA. Using single nucleotide polymorphism data, we assessed genetic structure among populations occurring at the interface of two abutting evolutionary lineages, and at a fine scale among habitat fragments within the heavily urbanized area. Based on the ecology of P. blainvillii , we predicted which environmental variables influence population structure and gene flow and used gravity models to distinguish among hypotheses to best explain population connectivity. Our results show evidence of admixture between two evolutionary lineages and strong population genetic structure across small habitat fragments. We also show that topography, microclimate, and soil and vegetation types are important predictors of functional connectivity, and that anthropogenic disturbance, including recent fire history and urban development, are key factors impacting contemporary population dynamics. Examining how natural and anthropogenic sources of landscape variation affect contemporary population genetics is critical to understanding how to best manage sensitive species in a rapidly changing landscape.

California↗
USGS2023

Satellite-derived plant cover maps vary in performance depending on version and product

Understanding the accuracy and appropriate application scale of satellite-derived maps of vegetation cover is essential for effective management of the vast, remote rangelands of the world. However, the underlying models are updated frequently and may combine with rapidly changing vegetation conditions to cause variations in accuracy and precision over time. We sought to assess how model performance changed between different versions of satellite-derived cover products (Rangeland Analysis Platform, RAP, and Rangeland Condition Monitoring and Assessment Protocol, RCMAP) and how the performance of LandCart compared to RAP and RCMAP. Additionally, we asked how variability in agreement between LandCart and field-based models varied with scale. We utilized an intensive dataset of grid-point intercept functional group cover data collected between 2016 and 2020 across the ∼113 kHA 2015 Soda Wildfire to 1) evaluate r 2 agreement between versions of each satellite-derived product and plot-level field data and 2) assess relative standard error of agreement in cover between LandCart and continuous field-based Empirical Bayesian Kriging (EBK) regression models. Agreement between satellite- compared to field-plot values of cover (r 2 ) increased for RCMAP Version 5.0 compared to Version 2.0, but there were negligible changes between versions of RAP. Despite this, r 2 values of RCMAP and LandCart were nearly always less than RAP. Variability in agreement between EBK regression model cover and LandCart-derived cover decreased with the scale of consideration. Variability in agreement between satellite-derived cover products and field-based metrics is lowest at larger scale (mega-fire or regional) and varies from year to year and across versions, which could complicate detection of temporal changes in plant cover.

Idaho, Oregon↗
USGS2009

Twentieth-century decline of large-diameter trees in Yosemite National Park, California, USA

Studies of forest change in western North America often focus on increased densities of small-diameter trees rather than on changes in the large tree component. Large trees generally have lower rates of mortality than small trees and are more resilient to climate change, but these assumptions have rarely been examined in long-term studies. We combined data from 655 historical (1932-1936) and 210 modern (1988-1999) vegetation plots to examine changes in density of large-diameter trees in Yosemite National Park (3027 km 2 ). We tested the assumption of stability for large-diameter trees, as both individual species and communities of large-diameter trees. Between the 1930s and 1990s, large-diameter tree density in Yosemite declined 24%. Although the decrease was apparent in all forest types, declines were greatest in subalpine and upper montane forests (57.0% of park area), and least in lower montane forests (15.3% of park area). Large-diameter tree densities of 11 species declined while only 3 species increased. Four general patterns emerged: (1) Pinus albicaulis, Quercus chrysolepis, and Quercus kelloggii had increases in density of large-diameter trees occur throughout their ranges; (2) Pinus jeffreyi, Pinus lambertiana, and Pinus ponderosa, had disproportionately larger decreases in large-diameter tree densities in lower-elevation portions of their ranges; (3) Abies concolor and Pinus contorta, had approximately uniform decreases in large-diameter trees throughout their elevational ranges; and (4) Abies magnifica, Calocedrus decurrens, Juniperus occidentalis, Pinus monticola, Pseudotsuga menziesii, and Tsuga mertensiana displayed little or no change in large-diameter tree densities. In Pinus ponderosa-Calocedrus decurrens forests, modern large-diameter tree densities were equivalent whether or not plots had burned since 1936. However, in unburned plots, the large-diameter trees were predominantly A. concolor, C. decurrens, and Q. chrysolepis, whereas P. ponderosa dominated the large-diameter component of burned plots. Densities of large-diameter P. ponderosa were 8.1 trees ha -1 in plots that had experienced fire, but only 0.5 trees ha -1 in plots that remained unburned. ?? 2009 Elsevier B.V. All rights reserved.

Forest Ecology and Management↗
USGS2021

The snag’s the limit: Habitat selection modeling for the western purple martin in a managed forest landscape

The western purple martin ( Progne subis arboricola ), an avian insectivore, is a species of conservation concern throughout the Pacific Northwest. Compared to the well-studied eastern subspecies ( Progne subis subis ), little is known of the life history and biology of the western subspecies. Availability of breeding habitat is believed to be a major limiting factor for western purple martins in forested habitat, but fundamental information on their current distribution and selection of nesting habitat is deficient. To fill this gap, we compared habitat characteristics at three spatial scales (snag-level, stand-level [48.6 ha], landscape-level [314 ha]) surrounding nest snags occupied by purple martins in western Oregon to unoccupied sites. We found habitat for nesting purple martins was defined by the presence of moderately decayed snags with nest cavities, located well away from closed-canopy forest in sufficiently large (>15 ha) open areas. Our modeling efforts suggested suitable habitat was rare within the study region because: 1) snags were scarce on private industrial forest lands and 2) large disturbed patches were uncommon on federal lands. We conclude that a disturbance regime characterized by infrequent but major stand-replacing events, such as fire or timber harvest, is likely the key to maintaining breeding habitat for purple martins in upland forests in western Oregon.

Oregon↗
USGS2017

Regeneration and invasion of cottonwood riparian forest following wildfire

Populus deltoides is considered to be a weak resprouter and highly susceptible to wildfire, but few post-wildfire studies have tracked P. deltoides response and resprouting within the Great Plains of North America. Following a wildfire in southwestern Kansas, U.S.A., we surveyed burned and unburned areas of a cottonwood riparian forest along the Cimarron River that included a major understory invader, tamarisk ( Tamarix ramosissima Ledeb.). We tested the following hypotheses, which are consistent with the current understanding of P. deltoides response to wildfire in the Great Plains: (1) regeneration of P. deltoides will be low in areas burned by the wildfire; (2) the number of dead P. deltoides individuals will be greater in the wildfire than unburned areas; and (3) tamarisk regeneration will be higher than P. deltoides regeneration in the wildfire areas because tamarisk is considered a stronger resprouter. We found evidence contrary to two of our hypotheses 3 years following the wildfire. (1) P. deltoides regeneration was high following the wildfire, averaging 692 individuals/ha. (2) The number of dead mature cottonwood trees was greater in wildfire plots than in unburned plots. (3) There was more P. deltoides regeneration than tamarisk regeneration following wildfire. These findings, which diverge from the majority of studies examining P. deltoides regeneration in the Great Plains, suggest that differing local environmental and forest stand conditions, coupled with the timing and intensity of the fire, could be important determinants of riparian forest species' responses to wildfire.

Kansas↗
USGS2011

The efficacy of salvage logging in reducing subsequent fire severity in conifer-dominated forests of Minnesota, USA

Although primarily used to mitigate economic losses following disturbance, salvage logging has also been justified on the basis of reducing fire risk and fire severity; however, its ability to achieve these secondary objectives remains unclear. The patchiness resulting from a sequence of recent disturbances—blowdown, salvage logging, and wildfire—provided an excellent opportunity to assess the impacts of blowdown and salvage logging on wildfire severity. We used two fire‐severity assessments (tree‐crown and forest‐floor characteristics) to compare post‐wildfire conditions among three treatment combinations (Blowdown–Salvage–Fire, Blowdown–Fire, and Fire only). Our results suggest that salvage logging reduced the intensity (heat released) of the subsequent fire. However, its effect on severity (impact to the system) differed between the tree crowns and forest floor: tree‐crown indices suggest that salvage logging decreased fire severity (albeit with modest statistical support), while forest‐floor indices suggest that salvage logging increased fire severity. We attribute the latter finding to the greater exposure of mineral soil caused by logging operations; once exposed, soils are more likely to register the damaging effects of fire, even if fire intensity is not extreme. These results highlight the important distinction between fire intensity and severity when formulating post‐disturbance management prescriptions.

Minnesota↗
USGS2026

Long-term monitoring identifies increase in Henslow’s Sparrow (Centronyx henslowii) abundance following fire management in a North Carolina grassland

Understanding population responses to environmental change is critical for assessing vulnerability, resilience, and habitat management needs. We assessed Henslow’s Sparrow ( Centronyx henslowii ) abundance and breeding productivity in an isolated North Carolina grassland (1149 ha) that transitioned from unmanaged to fire-managed during 2011–2024. Fire management was initiated in 2016, where approximately 1/3 of the grassland is burned annually in late summer on a rotating basis, resulting in a full burn cycle of roughly three years. We used hierarchical distance sampling models to estimate the change in Henslow’s Sparrow abundance before and after fire management from point count data (45–50 locations surveyed annually). Estimated average abundances (i.e., expected number of singing male sparrows per site) significantly increased from 1.387 individuals per survey location pre-management (95% credible interval [CI]: 0.822–2.267) to 3.124 post-management (CI: 2.235–4.385), resulting in annual population sizes ranging from 56 singing male sparrows in 2012 (CI: 36–85), to 411 in 2022 (CI: 342–498). From 2022 to 2023, average brood size was 3.148 (95% confidence interval [CI]: 2.637–3.659) and survival probability for a 24-day nesting cycle was 0.693 (CI: 0.369–0.897). Apparent nesting success was 70–89%, much higher than reported in previous studies (19–62%). Increased abundance post-management indicates that Henslow’s Sparrows are responding positively to the use of prescribed fire, while the estimated rates of breeding productivity indicate the species likely has the capacity to sustain the local population. This study provides baseline information for managers to monitor population status, while laying the foundation to identify regulatory mechanisms and gauge the effectiveness of the current fire management strategy in maintaining an isolated population of Henslow’s Sparrows.

North Carolina↗
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↗
USGS2006

Nest survival of clay-colored and vesper sparrows in relation to woodland edge in mixed-grass prairies

The quantity and quality of northern mixed-grass prairie continues to decline because of conversion to agriculture, invasion of woody and exotic plants, and disruption of important ecological processes that shape grasslands. Declines in grassland bird populations in North Dakota, USA, have coincided with these largely anthropogenic alterations to prairie habitat. In grasslands of north-central and northwestern North Dakota, woody plants have increased due primarily to fire suppression, extirpation of bison (Bos bison), and widescale planting of tree shelter belts. In northern grasslands, effects of woody vegetation on survival of grassland birds are poorly understood, and conclusions are based mainly on studies conducted outside the region. We examined nest survival of clay-colored sparrows (Spizella pallida) and vesper sparrows (Pooecetes gramineus) relative to the distance nests were located from aspen (Populus tremuloides,) woodland edges and relative to other habitat features near the nest. Clay-colored and vesper sparrow nest survival was higher for nests located near woodland edges, nests with greater cover of Kentucky bluegrass (Poa pratensis), and nests more concealed by vegetation. Vesper sparrow nest survival increased as the percent cover of tall shrubs near the nest increased. Based on video-camera data, the 13-lined ground squirrel (Spermophilus tridecemlineatus,) was the most common predator of sparrow eggs and young. Thirteen-lined ground squirrels were more common far from woodland edges than near, and this pattern may, in part, explain clay-colored and vesper sparrow nest survival in relation to woodland edges. In contrast to our results, studies conducted in other grassland systems generally report lower nest survival for grassland birds nesting near trees and shrubs. This disparity in results demonstrates the need to identify specific nest predators and their distributions with respect to important habitat features because these data can be important in explaining-and perhaps predicting-patterns of nest predation.

Journal of Wildlife Management↗
USGS2016

Tree island pattern formation in the Florida Everglades

The Florida Everglades freshwater landscape exhibits a distribution of islands covered by woody vegetation and bordered by marshes and wet prairies. Known as “tree islands”, these ecogeomorphic features can be found in few other low gradient, nutrient limited freshwater wetlands. In the last few decades, however, a large percentage of tree islands have either shrank or disappeared in apparent response to altered water depths and other stressors associated with human impacts on the Everglades. Because the processes determining the formation and spatial organization of tree islands remain poorly understood, it is still unclear what controls the sensitivity of these landscapes to altered conditions. We hypothesize that positive feedbacks between woody plants and soil accretion are crucial to emergence and decline of tree islands. Likewise, positive feedbacks between phosphorus (P) accumulation and trees explain the P enrichment commonly observed in tree island soils. Here, we develop a spatially-explicit model of tree island formation and evolution, which accounts for these positive feedbacks (facilitation) as well as for long range competition and fire dynamics. It is found that tree island patterns form within a range of parameter values consistent with field data. Simulated impacts of reduced water levels, increased intensity of drought, and increased frequency of dry season/soil consuming fires on these feedback mechanisms result in the decline and disappearance of tree islands on the landscape.

Florida↗
USGS2018

Evaluating and monitoring forest fuel treatments using remote sensing applications in Arizona, U.S.A.

The practice of fire suppression across the western United States over the past century has led to dense forests, and when coupled with drought has contributed to an increase in large and destructive wildfires. Forest management efforts aimed at reducing flammable fuels through various fuel treatments can help to restore frequent fire regimes and increase forest resilience. Our research examines how different fuel treatments influenced burn severity and post-fire vegetative stand dynamics on the San Carlos Apache Reservation, in east-central Arizona, U.S.A. Our methods included the use of multitemporal remote sensing data and cloud computing to evaluate burn severity and post-fire vegetation conditions as well as statistical analyses. We investigated how forest thinning, commercial harvesting, prescribed burning, and resource benefit burning (managed wildfire) related to satellite measured burn severity (the difference Normalized Burn Ratio – dNBR) following the 2013 Creek Fire and used spectral measures of post-fire stand dynamics to track changes in land surface characteristics (i.e., brightness, greenness and wetness). We found strong negative relationships between dNBR and post-fire greenness and wetness, and a positive non-linear relationship between dNBR and brightness, with greater variability at higher severities. Fire severity and post-fire surface changes also differed by treatment type. Our results showed harvested and thinned sites that were not treated with prescribed fire had the highest severity fire. When harvesting was followed by a prescribed burn, the sites experienced lower burn severity and reduced post-fire changes in vegetation greenness and wetness. Areas that had previously experienced resource benefit burns had the lowest burn severities and the highest post-fire greenness measurements compared to all other treatments, except for where the prescribed burn had occurred. These results suggest that fire treatments may be most effective at reducing the probability of hazardous fire and increasing post-fire recovery. This research demonstrates the utility of remote sensing and spatial data t o inform forest management, and how various fuel treatments can influence burn severity and post-fire vegetation response within ponderosa pine forests across the southwestern U.S.

Arizona↗
USGS2018

Climate, disturbance, and vulnerability to vegetation change in the Northwest Forest Plan Area

Climate change is expected to alter the composition, structure, and function of forested ecosystems in the United States (Vose et al. 2012). Increases in atmospheric concentrations of greenhouse gases (e.g., carbon dioxide [CO2]) and temperature, as well as altered precipitation and disturbance regimes (e.g., fire, insects, pathogens, and windstorms), are expected to have profound effects on biodiversity, socioeconomics, and the delivery of ecosystem services within the Northwest Forest Plan (NWFP, or Plan) area over the next century (Dale et al. 2001, Franklin et al. 1991). The ecological interactions and diversity of biophysical settings in the region are complex. The effects of climate change on ecological processes will occur through a variety of mechanisms at a range of spatial scales and levels of biological organization, ranging from the physiological responses of individual plants to the composition and structure of stands and landscapes (Peterson et al. 2014a). Understanding and incorporating how climate change projections and the potential ecological effects and uncertainties differ within the region (e.g., Deser et al. 2012) is essential for developing adaptation and mitigation strategies.

California, Oregon, Washington↗
USGS2016

Resprouting and seeding hypotheses: A test of the gap-dependent model using resprouting and obligate seeding subspecies of Arctostaphylos

Ecological factors favoring either postfire resprouting or postfire obligate seeding in plants have received considerable attention recently. Three ecological models have been proposed to explain patterns of these two life history types. In this study, we test these three models using data from California chaparral. We take an innovative approach to testing these models by not testing community or landscape patterns, but instead, investigating vegetation structure characteristic of four pairs of resprouting and (non-resprouting) obligate seeding subspecies of Arctostaphylos (Ericaceae), a dominant and diverse shrub genus in California chaparral. Data were analyzed for percentage bare ground, elevation, annual precipitation, number of fires, and time between fires and were compared independently for each subspecies pair. Results were consistently supportive of the gap-dependent model suggesting that obligate seeders are favored when post-disturbance gaps are large. Results were inconclusive or contrary to expectations for both of the other two models.

Plant Ecology↗
USGS2010

Water quality and ecological condition of urban streams in Independence, Missouri, June 2005 through December 2008

To identify the sources of selected constituents in urban streams and better understand processes affecting water quality and their effects on the ecological condition of urban streams and the Little Blue River in Independence, Missouri the U.S. Geological Survey in cooperation with the City of Independence Water Pollution Control Department initiated a study in June 2005 to characterize water quality and evaluate the ecological condition of streams within Independence. Base-flow and stormflow samples collected from five sites within Independence, from June 2005 to December 2008, were used to characterize the physical, chemical, and biologic effects of storm runoff on the water quality in Independence streams and the Little Blue River. The streams draining Independence-Rock Creek, Sugar Creek, Mill Creek, Fire Prairie Creek, and the Little Blue River-drain to the north and the Missouri River. Two small predominantly urban streams, Crackerneck Creek [12.9-square kilometer (km2) basin] and Spring Branch Creek (25.4-km2 basin), were monitored that enter into the Little Blue River between upstream and downstream monitoring sites. The Little Blue River above the upstream site is regulated by several reservoirs, but streamflow is largely uncontrolled. The Little Blue River Basin encompasses 585 km2 with about 168 km2 or 29 percent of the basin lying within the city limits of Independence. Water-quality samples also were collected for Rock Creek (24.1-km2 basin) that drains the western part of Independence. Data collection included streamflow, physical properties, dissolved oxygen, chloride, metals, nutrients, common organic micro-constituents, and fecal indicator bacteria. Benthic macroinvertebrate community surveys and habitat assessments were conducted to establish a baseline for evaluating the ecological condition and health of streams within Independence. Additional dry-weather screenings during base flow of all streams draining Independence were conducted to identify point-source discharges and other sources of potential contamination. Regression models were used to estimate continuous and annual flow-weighted concentrations, loadings, and yields for chloride, total nitrogen, total phosphorus, suspended sediment, and Escherichia coli bacteria densities. Base-flow and stormflow water-quality samples were collected at five sites within Independence. Base-flow samples for Rock Creek and two tributary streams to the Little Blue River exceeded recommended U.S. Environmental Protection Agency standards for the protection of aquatic life for total nitrogen and total phosphorus in about 90 percent of samples, whereas samples collected at two Little Blue River sites exceeded both the total nitrogen and total phosphorus standards less often, about 30 percent of the time. Dry-weather screening identified a relatively small number (14.0 percent of all analyses) of potential point-source discharges for total chlorine, phenols, and anionic surfactants. Stormflow had larger median measured concentrations of total common organic micro-constituents than base flow. The four categories of common organic micro-constituents with the most total detections in stormflow were pesticides (100 percent), polyaromatic hydrocarbons and combustion by-products (99 percent), plastics (93 percent), and stimulants (91 percent). Most detections of common organic micro-constituents were less than 2 micrograms per liter. Median instantaneous Escherichia coli densities for stormflow samples showed a 21 percent increase measured at the downstream site on the Little Blue River from the sampled upstream site. Using microbial source-tracking methods, less than 30 percent of Escherichia coli bacteria in samples were identified as having human sources. Base-flow and stormflow data were used to develop regression equations with streamflow and continuous water-quality data to estimate daily concentrations, loads, and yields of various water-quality contaminants.

Scientific Investigations Report↗