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Ecological Health (ecological + health)
Selected AbstractsWildfire Policy and Public Lands: Integrating Scientific Understanding with Social Concerns across LandscapesCONSERVATION BIOLOGY, Issue 4 2004MICHAEL P. DOMBECK administración de bosques; fuego no controlado; política; Servicio Forestal Estados Unidos; tierras públicas Abstract:,Efforts to suppress wildfires have become increasingly problematic in recent years as costs have risen, threats to firefighter safety have escalated, and detrimental impacts to ecosystems have multiplied. Wildfires that escape initial suppression often expand into large, high-intensity summer blazes. Lost is the legacy of smaller fires that likely burned outside extreme weather and fuel conditions and resulted in less severe impacts. Despite the recognized need for modifications to existing policies and practices, resource agencies have been slow to respond. The spread of exotic species, climate change, and increasing human development in wildlands further complicates the issue. New policies are needed that integrate social and ecological needs across administrative boundaries and broad landscapes. These policies should promote a continuum of treatments with active management and reduction of fuel hazard in wildland-urban interface zones and reintroduction of fire in wildlands. Management goals should focus on restoration of the long-term ecological health of the land. Projects that reduce fuel loads but compromise the integrity of soil, water supplies, or watersheds will do more harm than good in the long run. Despite significant ecological concerns, learning to live with fire remains primarily a social issue that will require greater political leadership, agency innovation, public involvement, and community responsibility. Resumen:,En años recientes, los esfuerzos para suprimir los fuegos no controlados se han vuelto cada vez más problemáticos por el incremento de costos, el aumento de las amenazas a la seguridad de bomberos y se la multiplicio, de los impactos perjudiciales a los ecosistemas. Los incendios que escapan la supresión inicial a menudo se expanden a grandes conflagraciones estivales de alta intensidad. Se ha perdido el legado de fuegos menores que probablemente se llevaban a cabo en condiciones climáticas y de combustible extremas que tenían impactos menos severos. A pesar del reconocimiento de la necesidad de modificaciones a las políticas y prácticas actuales, las agencias han respondido lentamente. La expansión de especies exóticas, el cambio climático y el incremento del desarrollo humano en áreas silvestres complican el problema aún más. Se requieren políticas nuevas que integren necesidades sociales y ecológicas más allá de límites administrativos y en paisajes amplios. Estas políticas deben promover un continuo de tratamientos con gestión activa y reducción de riesgo de combustión en la interfase área silvestre-urbana y la reintroducción de fuego en áreas silvestres. Las metas de la gestión deben enfocar en la restauración de la salud ecológica a largo plazo. Los proyectos que reducen la carga de combustible pero que comprometen la integridad del suelo, las reservas de agua o cuencas hidrológicas no serán de mucha utilidad en el largo plazo. A pesar de preocupaciones ecológicas significativas, aprender a vivir con fuego seguirá siendo un aspecto social que requerirá de mayor liderazgo político, innovación de agencias, participación del público y responsabilidad comunitaria. [source] Influences of the vegetation mosaic on riparian and stream environments in a mixed forest-grassland landscape in "Mediterranean" northwestern CaliforniaECOGRAPHY, Issue 4 2005Hartwell H. Welsh We examined differences in riparian and aquatic environments within the three dominant vegetation patch types of the Mattole River watershed, a 789-km2 mixed conifer-deciduous (hardwood) forest and grassland-dominated landscape in northwestern California, USA. Riparian and aquatic environments, and particularly microclimates therein, influence the distributions of many vertebrate species, particularly the physiologically-restricted ectotherms , reptiles and amphibians (herpetofauna), and fishes. In addition to being a significant portion of the native biodiversity of a landscape, the presence and relative numbers of these more tractable small vertebrates can serve as useful metrics of its "ecological health." Our primary objective was to determine the range of available riparian and aquatic microclimatic regimes, and discern how these regimes relate to the dominant vegetations that comprise the landscape mosaic. A second objective, reported in a companion paper, was to examine relationships between available microclimatic regimes and herpetofaunal distributions. Here we examined differences in the composition, structure, and related environmental attributes of the three dominant vegetation types, both adjacent to and within the riparian corridors along 49 tributaries. Using automated dataloggers, we recorded hourly water and air temperatures and relative humidity throughout the summer at a representative subset of streams; providing us with daily means and amplitudes for these variables within riparian environments during the hottest period. Although the three vegetation types that dominate this landscape each had unique structural attributes, the overlap in plant species composition indicates that they represent a seral continuum. None-the-less, we found distinct microclimates in each type. Only riparian within late-seral forests contained summer water temperatures that could support cold-water-adapted species. We evaluated landscape-level variables to determine the best predictors of water temperature as represented by the maximum weekly maximum temperature (MWMT). The best model for predicting MWMT (adj. R2=0.69) consisted of catchment area, aspect, and the proportion of non-forested (grassland) patches. Our model provides a useful tool for management of cold-water fauna (e.g. salmonids, stream amphibians) throughout California's "Mediterranean" climate zone. [source] Oxidative mutagenicity of polar fractions from polycyclic aromatic hydrocarbon,contaminated soilsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2008Joanna Park Abstract Soils at hazardous waste sites contain complex mixtures of chemicals and often are difficult to characterize in terms of risk to human and ecological health. Over time, biogeochemical processes can decrease the apparent concentrations of pollutants but also can lead to accumulation of new products for which toxicity and behavior in the environment are largely unknown. A bioassay-directed fractionation technique was used to assess the contribution of redox-active bacterial metabolites to the toxicity of soil contaminated with polycyclic aromatic hydrocarbons (PAHs). A reverse mutation assay with Escherichia coli WP2 uvrA/pKM101 (IC188) and E. coli WP2 uvrA oxyR/pKM101 (IC203) was used to screen fractions for genotoxicity. Strain IC203 carries the ,oxyR30 mutation, which prevents the expression of antioxidant proteins in response to oxidative stress and increases its reversion by compounds that generate reactive oxygen species (ROS). Polar fractions of PAH-contaminated soil extracts were mutagenic to strain IC203 but not to strain IC188, suggesting the involvement of ROS in genotoxicity. Genotoxic potencies ranged from 300 to 1,700 revertants per milligram of fraction. Catalase was able to decrease IC203 reversion, implicating the involvement of hydrogen peroxide as a key ROS. Oxidized PAH compounds, including quinones, were identified in the mutagenic fractions but were not by themselves mutagenic. Deasphalted whole extracts and recombined fractions were not mutagenic, indicating that interactions between compounds in different fractions can mitigate genotoxicity. [source] A comparison of bacteria and benthic invertebrates as indicators of ecological health in streamsFRESHWATER BIOLOGY, Issue 7 2009G. LEAR Summary 1. We set out to evaluate the reliability of bacterial communities as an indicator of freshwater ecological health. 2. Samples of epilithic biofilm were taken over a 1-year period from four streams, each impacted by varying degrees of human modification. The bacteria within each sample were characterised using a whole community DNA fingerprinting technique (automated ribosomal intergenic spacer analysis). Spatial and temporal differences in community structure between samples were visualised using multi-dimensional scaling and quantified using permutational multivariate anova. Macrobenthic invertebrates, which are commonly used as indicators of stream ecological health, were also sampled for comparison. 3. Multivariate analysis revealed a clear gradient in macroinvertebrate community structure between sites exposed to increased human impact. Bacterial communities, however, could only distinguish the most impacted site from the remainder. 4. Additional research is required to increase the sensitivity of bacterial community analyses before endorsing their use as an indicator of freshwater ecological health. [source] Modelling stream flow for use in ecological studies in a large, arid zone river, central AustraliaHYDROLOGICAL PROCESSES, Issue 6 2005Justin F. Costelloe Abstract Australian arid zone ephemeral rivers are typically unregulated and maintain a high level of biodiversity and ecological health. Understanding the ecosystem functions of these rivers requires an understanding of their hydrology. These rivers are typified by highly variable hydrological regimes and a paucity, often a complete absence, of hydrological data to describe these flow regimes. A daily time-step, grid-based, conceptual rainfall,runoff model was developed for the previously uninstrumented Neales River in the arid zone of northern South Australia. Hourly, logged stage data provided a record of stream-flow events in the river system. In conjunction with opportunistic gaugings of stream-flow events, these data were used in the calibration of the model. The poorly constrained spatial variability of rainfall distribution and catchment characteristics (e.g. storage depths) limited the accuracy of the model in replicating the absolute magnitudes and volumes of stream-flow events. In particular, small but ecologically important flow events were poorly modelled. Model performance was improved by the application of catchment-wide processes replicating quick runoff from high intensity rainfall and improving the area inundated versus discharge relationship in the channel sections of the model. Representing areas of high and low soil moisture storage depths in the hillslope areas of the catchment also improved the model performance. The need for some explicit representation of the spatial variability of catchment characteristics (e.g. channel/floodplain, low storage hillslope and high storage hillslope) to effectively model the range of stream-flow events makes the development of relatively complex rainfall,runoff models necessary for multisite ecological studies in large, ungauged arid zone catchments. Grid-based conceptual models provide a good balance between providing the capacity to easily define land types with differing rainfall,runoff responses, flexibility in defining data output points and a parsimonious water-balance,routing model. Copyright © 2004 John Wiley & Sons, Ltd. [source] The role of monitored natural recovery in sediment remediationINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 1 2006Victor S Magar Abstract The long-term goal of monitored natural recovery (MNR) is to achieve ecological recovery of biological endpoints in order to protect human and ecological health. Insofar as ecological recovery is affected by surface-sediment-contaminant concentrations, the primary recovery processes for MNR are natural sediment burial and contaminant transformation and weathering to less toxic forms. This paper discusses the overall approach for effective implementation of MNR for contaminated sediment sites. Several lines of evidence that may be used to demonstrate natural recovery processes are summarized, including documentation of source control; evidence of contaminant burial; measurement of surface sediment mixing depths and the active sediment benthic layer; measurement of sediment stability; contaminant transformation and weathering; modeling sediment transport, contaminant transport, and ecological recovery; measuring ecological recovery and long-term risk reduction; knowledge of future plans for use and development of the site; and watershed and institutional controls. In general, some form of natural recovery is expected and should be included as part of a remedy at virtually all contaminated sediment sites. Further, MNR investigations and an understanding of natural recovery processes provide cost-effective information and support the evaluation of more aggressive remedies such as capping, dredging, and the use of novel amendments. The risk of dredging or capping may be greater than the risk of leaving sediments in place at sites where capping or dredging offer little long-term environmental gain but pose significant short-term risks for workers, local communities, and the environment. [source] Choosing remediation and waste management options at hazardous and radioactive waste sitesREMEDIATION, Issue 1 2002Michael Greenberg This article discusses a process for finding insights that will allow federal agencies and environmental professionals to more effectively manage contaminated sites. The process is built around what Etzioni (1968) called mixed-scanning, that is, perpetually doing both comprehensive and detailed analyses and periodically re-scanning for new circumstances that change the decision-making environment. The article offers a checklist of 127 items, which is one part of the multiple-stage scanning process. The checklist includes questions about technology; public, worker, and ecological health; economic cost and benefits; social impacts; and legal issues. While developed for a DOE high-level radioactive waste application, the decision-making framework and specific questions can be used for other large-scale remediation and management projects. © 2002 Wiley Periodicals, Inc. [source] | |||||||||||||