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721.
Pearlstine LG Smith SE Brandt LA Allen CR Kitchens WM Stenberg J 《Journal of environmental management》2002,66(2):127-144
The Florida Gap (Fl-Gap) project provides an assessment of the degree to which native animal species and natural communities are or are not represented in existing conservation lands. Those species and communities not adequately represented in areas being managed for native species constitute 'gaps' in the existing network of conservation lands. The United States Geological Survey Gap Analysis Program is a national effort and so, eventually, all 50 states will have completed it. The objective of Fl-Gap was to provide broad geographic information on the status of terrestrial vertebrates, butterflies, skippers and ants and their respective habitats to address the loss of biological diversity. To model the distributions and potential habitat of all terrestrial species of mammals, breeding birds, reptiles, amphibians, butterflies, skippers and ants in Florida, natural land cover was mapped to the level of dominant or co-dominant plant species. Land cover was classified from Landsat Thematic Mapper (TM) satellite imagery and auxiliary data such as the national wetlands inventory (NWI), soils maps, aerial imagery, existing land use/land cover maps, and on-the-ground surveys. Wildlife distribution models were produced by identifying suitable habitat for each species within that species' range. Mammalian models also assessed a minimum critical area required for sustainability of the species' population. Wildlife species richness was summarized against land stewardship ranked by an area's mandates for conservation protection. 相似文献
722.
Smith WB 《Environmental pollution (Barking, Essex : 1987)》2002,116(Z1):S233-S242
Forests provide significant commodity and noncommodity values to the citizens of the United States. An important and substantial role in ensuring the continued health, productivity, and sustainability of these resources is a reliable and credible inventory and monitoring program. The Forest Inventory and Analysis (FIA) program of the US Forest Service has been monitoring and reporting on status, condition, and trends in the nation's forests for over 70 years and the Forest Health Monitoring (FHM) program for the last 11 years. Recent legislation included in the 1998 Farm Bill, along with efforts to integrate inventory and monitoring networks to deliver Criteria and Indicators of Sustainable Forests, are redefining the role and operation of the recently integrated FIA and FHM programs. This paper provides a brief history and a look at new directions for the enhanced FIA Program. 相似文献
723.
Fowler D. Sutton M. A. Flechard C. Cape J. N. Storeton-West R. Coyle M. Smith R. I. 《Water, Air, & Soil Pollution: Focus》2001,1(5-6):39-48
Two years of continuous measurements of SO2deposition fluxes to moorland vegetation are reported. The mean flux of 2.8 ng SO2 m-2 s-1 is regulated predominantly by surface resistance (r
c) which, even for wet surfaces, was seldom smaller than 100 s m-1. The control of surface resistance is shown to be regulated by the ratio of NH3SO2 concentrations with an excess of NH3 generating the small surface resistances for SO2. A dynamic surface chemistry model is used to simulate the effects of NH3 on SO2 deposition flux and is able to capture responses to short-term changes in ambient concentrations of SO2, NH3 and meteorological conditions. The coupling between surface resistance and NH3/SO2 concentration ratios shows that the deposition velocity for SO2 is regulated by the regional pollution climate. Recent long-term SO2 flux measurements in a transect over Europe demonstrate the close link between NH3/SO2 concentrations and rc (SO2). The deposition velocity for SO2 is predicted to have increased with time since the 1970s and imply a 40% increase in v
d at a site at which the annual mean ambient SO2 concentrations declined from 47 to 3 g m-3 between 1973 and 1998. 相似文献
724.
Identifying Influences on Model Uncertainty: An Application Using a Forest Carbon Budget Model 总被引:2,自引:0,他引:2
Uncertainty is an important consideration for both developers and users of environmental simulation models. Establishing quantitative
estimates of uncertainty for deterministic models can be difficult when the underlying bases for such information are scarce.
We demonstrate an application of probabilistic uncertainty analysis that provides for refinements in quantifying input uncertainty
even with little information. Uncertainties in forest carbon budget projections were examined with Monte Carlo analyses of
the model FORCARB. We identified model sensitivity to range, shape, and covariability among model probability density functions,
even under conditions of limited initial information. Distributional forms of probabilities were not as important as covariability
or ranges of values. Covariability among FORCARB model parameters emerged as a very influential component of uncertainty,
especially for estimates of average annual carbon flux. 相似文献
725.
Smith V Fegan M Pollard D Long S Hayden E Ryan TP 《Journal of environmental radioactivity》2001,56(3):269-284
Technetium-99 activity concentrations in seawater and biota from Irish coastal waters are presented. Time series measurements of 99Tc in seawater and Fucus vesiculosus from the western Irish Sea show that activity concentrations have increased in line with the increase in discharges of 99Tc from Sellafield. The peak in activity concentrations in both seawater and Fucus vesiculosus occurred in 1997 approximately two years after the peak in 99Tc discharges. The highest activity concentration recorded in Fucus vesiculosus showed a 29-fold increase over the mean concentration for the period 1988-1993. Technetium-99 activity concentrations were measured in fish, lobsters, prawns, mussels and oysters landed at major fishing ports on the east and northeast coasts of Ireland between 1996 and 1998. Concentration factors for 99Tc in the brown seaweed Fucus vesiculosus and certain species of fish, crustaceans and molluscs from the Irish Sea were estimated. In general, these concentration factors were higher than those in the literature which were derived from laboratory studies, but agreed well with values which were based on field studies. The mean committed effective doses to Irish typical and heavy seafood consumers due to 99Tc in the period 1996-1998 were 0.061 and 0.24 microSv, respectively. 相似文献
726.
D. Fowler M. O’Donoghue J. B. A. Muller R. I. Smith U. Dragosits U. Skiba M. A. Sutton P. Brimblecombe 《Water, Air, & Soil Pollution: Focus》2005,4(6):9-23
Measurements of the concentrations of nitrogen compounds in air and precipitation in the UK have been made since the mid-19th century, but no networks operating to common protocols and having traceable analytical procedures were established until the 1950s. From 1986 onwards, a high-quality network of sampling stations for precipitation chemistry was established across the UK. In the following decade, monitoring networks provided measurement of NO2, NH3, HNO3 and a satisfactory understanding of the dry deposition process for these gases allowed dry deposition to be quantified. Maps of N deposition for oxidized and reduced compounds at a spatial scale of 5 km × 5 km are available from 1986 to 2000. Between 1950 and 1985, the more limited measurements, beginning with those of the European Air Chemistry Network (EACN) provide a reasonable basis to estimate wet deposition of NO? 3?N and NH+ 4?N. For the first half of the century, estimates of deposition were scaled with emissions assuming a constant relationship between emission and deposition for each of the components of the wet and dry deposition budget at the country scale. Emissions of oxidized N, which dominated total nitrogen emissions throughout the century, increased from 312 kt N annually in 1900 to a peak of 787 kt for the decade 1980–1990 and then declined to 460 kt in 2000. Emissions of reduced N, largely from coal combustion were about 168 kt N in 1900, increasing to a peak of 263 kt N in 2000 and by now dominated by agricultural sources. Reduced N dominated the deposition budget at the country scale, increasing from 163 kt N in 1900 to 211 kt N in 2000, while deposition of oxidized N was 66 kt N in 1900 and 191 kt N in 2000. Over the century, 68 Mt (Tg) of fixed N was emitted within the UK, 78% as NO x , while 29 Mt of nitrogen was deposited (43% of emissions), equivalent to 1.2 t N ha?1, on average, with 60% in the reduced form. Deposition to semi-natural ecosystems is approximately 15 Tg N, equivalent to between 1 and 5 t N ha?1, over the century and appears to be accumulating in soil. The N deposition over the century is similar in magnitude to the total soil N inventory in surface horizons. 相似文献
727.
Brian E. Haggard Paul B. DeLaune Douglas R. Smith Philip A. Moore 《Journal of the American Water Resources Association》2005,41(2):245-256
ABSTRACT: A main water quality concern is accelerated eutrophication of fresh waters from nonpoint source pollution, particularly nutrient transport in surface runoff from agricultural areas and confined animal feeding operations. This study examined nutrient and β17‐estradiol concentrations in runoff from small plots where six poultry litters were applied at a rate of about 67 kg/ha of total phosphorus (TP). The six poultry litter treatments included pelleted compost, pelleted litter, raw litter, alum (treated) litter, pelleted alum litter, and normal litter (no alum). Four replicates of the six poultry litter treatments and a control (plots without poultry litter application) were used in this study. Rainfall simulations at intensity of 50 mm/hr were conducted immediately following poultry litter application to the plots and again 30 days later. Composite runoff samples were analyzed for soluble reactive phosphorus (SRP), ammonia (NH4), nitrate (NO3), TP, total nitrogen (TN) and β17‐estradiol concentrations. In general, poultry litter applications increased nutrient and β17‐estradiol concentrations in runoff water. Ammonia and P concentrations in runoff water from the first simulation were correlated to application rates of water extractable NH4 (R2= 0.70) and P (R2= 0.68) in the manure. Results suggest that alum applications to poultry litter in houses in between flocks is an effective best management practice for reducing phosphorus (P) and β17‐estradiol concentrations in runoff and that pelleted poultry litters may increase the potential for P and β17‐estradiol loss in runoff water. Inferences regarding pelleted poultry litters should be viewed cautiously, because the environmental consequence of pelleting poultry litters needs additional investigation. 相似文献
728.
Bonnie Colby Elizabeth Smith‐Incer 《Journal of the American Water Resources Association》2005,41(3):709-717
ABSTRACT: Preservation of the few remaining ecologically vital riparian areas in the southwestern United States is a significant policy concern. This article reports on two economic aspects of preserving a nationally renowned riparian birding area in Southern California. First, the article examines visitor willingness to pay (WTP) for habitat restoration and estimates an annual WTP of US $77 per visitor to preserve the habitat, about a half‐million dollars a year for estimated visitor numbers in 2000 and 2001. Second, it documents visitor expenditures in the local economy to be approximately three‐quarters of a million dollars per year. This direct visitor spending attributable to the riparian habitat generates around US $1.3 million in increased local business activity in this relatively remote rural area. 相似文献
729.
Small mammals are important predators of gypsy moths (Lymantria dispar L.), which are major defoliators of deciduous forests in the northeastern United States. Abundance and habitat relationships
of small mammals were studied during summers 1984 and 1985 on forested sites at Moshannon and Rothrock state forests in two
physiographic regions of Pennsylvania (Allegheny High Plateaus Province and Valley and Ridge Province, respectively) that
varied in potential susceptibility to defoliation. The white-footed mouse (Peromyscus leucopus), which is a major vertebrate predator of gypsy moths, was the most common small mammal on all sites. Of the four common
species, northern short-tailed shrews (Blarina brevicauda), southern red-backed voles (Clethrionomys gapperi), and white-footed mice were more abundant at Moshannon compared to Rothrock State Forest, but masked shrews (Sorex cinereus) were more abundant at Rothrock. Elevation was a major factor affecting abundance and distribution of small mammals. Because
of the greater abundance of small mammals and more suitable physiographic features at Moshannon compared to Rothrock State
Forest, small mammals may be more effective as predators on gypsy moths in the Allegheny High Plateaus than the Valley and
Ridge Province of Pennsylvania. 相似文献
730.
James A. Smith 《Journal of the American Water Resources Association》1991,27(1):39-46
ABSTRACT: A class of nonparametric procedures is developed for producing long-range streamflow forecasts. The forecasting procedures, which are based solely on daily streamflow data, utilize nonparametric regression to relate a forecast variable to a covariate variable. The forecast variable is a function of future streamflow and can take a wide variety of forms. The covariate variable is a function of antecedent streamflow. The forecasting procedures are quite flexible, both in terms of the duration of the forecast period and the types of forecast variables that can be considered. The procedures are used to develop long-term (1–4 months) forecasts of minimum daily flow of the Potomac River at Washington, D.C. This forecast information is an integral component of water management activities for the Washington, D.C. metropolitan area. 相似文献