emap statistical methods manual
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emap statistical methods manualThe methods described give procedures to estimate the current status of ecological resources that are appropriate for survey designs implemented by EMAP. The methods apply to analyses of EMAP regional demonstration studies and R-EMAP studies. The audience for the manual are statisticians of scientists with a reasonable background in statistics. The calculations are detailed so that a scientific computer programmer can implement the methods. The methods described give procedures to estimate the current status of ecological resources that are appropriate for survey designs implemented by EMAP. The calculations are detailed so that a scientific computer programmer can implement the methods. Please try again.The agency is charged with protecting human health and the environment, by writing and enforcing regulations based on laws passed by Congress. The EPA's struggle to protect health and the environment is seen through each of its official publications. These publications outline new policies, detail problems with enforcing laws, document the need for new legislation, and describe new tactics to use to solve these issues. This collection of publications ranges from historic documents to reports released in the new millennium, and features works like: Bicycle for a Better Environment, Health Effects of Increasing Sulfur Oxides Emissions Draft, and Women and Environmental Health. Then you can start reading Kindle books on your smartphone, tablet, or computer - no Kindle device required. Get your Kindle here, or download a FREE Kindle Reading App. Key elements of this process are ecologically meaningful indicators and cost-effective monitoring designs. The Environmental Monitoring and Assessment Program (EMAP) advances the science needed for measuring ecosystem condition and trends.http://sotel-perm.ru/site/dellorto-sha-carburetor-manual.xml
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Most recently the EMAP approach has been successfully used by participants in the Mid-Atlantic Integrated Assessment (MAIA), including EPA’s Office of Research and Development, EPA’s Region III, and the States of the Mid-Atlantic. The participants in MAIA have produced a regional landscape atlas, state of the estuaries report, and state of the streams report. The work in MAIA is currently moving from monitoring into the assessment phase. The Western EMAP Pilot (Western Pilot), will be a test of our current MAIA indicators and technology for applicability in western ecosystems. New indicators and designs may be needed in the Western Pilot for assessments at the level of EPA’s Regions, of the states, and of the Tribes; these assessments will be done so that they can be combined to provide regional assessments. Our coastal monitoring program in the Western estuaries will also be initiated shortly. Subsequently, this will be expanded to the Gulf and Atlantic coasts to provide the current condition of our national estuaries. By continuing to improve the science of monitoring, EMAP researchers will remove data gaps and allow the unequivocal assessment of the health of the nation’s resources. Keywords assessment ecology estuaries indicators mid-Atlantic monitoring scale trends West This is a preview of subscription content, log in to check access. Preview Unable to display preview. Download preview PDF. Unable to display preview. CrossRef Google Scholar Jackson, L., Kurtz, J. and Fisher, W. (eds.).: in press, Evaluation guidelines for ecological indicators, U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory. Google Scholar USEPA: in press, Mid-Atlantic Highlands State of the Streams, U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory.In: Sandhu S.S., Melzian B.D., Long E.R., Whitford W.G., Walton B.T. (eds) Monitoring Ecological Condition in the Western United States.http://anaheimmachining.com/admin/images/dellorto-sha-manual.xml Springer, Dordrecht. In the United States, ecological monitoring and assessment of GREs has lagged behind streams and estuaries, and the management of GREs is hampered by the lack of unbiased data at appropriate spatial scales. Properties of GREs that make them challenging to monitor and assess include difficult sample logistics and high habitat diversity. The U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP) has developed a comprehensive, regional-scale, survey-based monitoring approach to assessment of streams and estuaries, but has not yet conducted research on applying these tools to GRE monitoring. In this paper we present an overview of an EMAP research project on the Upper Missouri River (UMR). We summarize the assessment objectives for the study, the design for selecting sample locations, the indicators measured at these sites and the tools used to analyze data. We present an example of the type of statements that can be made with EMAP monitoring data. With modification, the set of methodologies developed by EMAP may be well suited for assessment of GREs in general. Subscription will auto renew annually. Taxes to be calculated in checkout. National Academy Press, Washington, DC. Annual Report, 2001.USDA: 2001, Forest Inventory and Analysis National Core Field Guide, Volume 1: Field Data Collection Procedures for Phase 2 Plots, version 1.5, U.S. Department of Agriculture, Forest Service, Washington, DC. USEPA: 1997, Guidelines for Preparation of the Comprehensive State Water Quality Assessments (305(b)) Reports. USEPA: 1998, Lake and Reservoir Bioassessment and Biocriteria Technical Guidance Document.Download citation Issue Date: March 2005 DOI: Keywords ecological assessment EMAP great rivers monitoring Missouri River survey design Subscription will auto renew annually. Taxes to be calculated in checkout. Received 2016 May 20; Accepted 2016 Aug 22. This article has been cited by other articles in PMC.http://www.diamondsinthemaking.com/content/boss-gt-pro-user-manual Abstract The US Environmental Protection Agency (US EPA) initiated planning in 2007 and conducted field work in 2011 for the first National Wetland Condition Assessment (NWCA) as part of the National Aquatic Resource Surveys (NARS). Not all of the estimated target population acres could be sampled due to accessibility and field issues. Keywords: Wetlands, Probability survey design, Wetland condition, Frame imperfections, Non-response Introduction In 2007, the US Environmental Protection Agency (US EPA) initiated planning for the National Wetland Condition Assessment (NWCA) as part of the National Aquatic Resource Surveys (NARS). The NWCA conducted field work in 2011 and was the fourth aquatic resource surveyed by NARS. It was preceded by coastal water, lake and reservoir, and river and stream assessments conducted in 2007 to 2010. In the early 1990s, the US EPA’s Environmental Monitoring and Assessment Program (EMAP) conducted research on approaches to monitoring wetland condition (Leibowitz et al. 1991 ). Their goal was “to provide a quantitative assessment of the current status and long-term trends in wetland condition on regional and national scales.” Leibowitz et al. ( 1993 ) considered alternative survey designs and conducted pilot studies to investigate the design’s feasibility (Ernst et al. 1995; Turner et al. 1995; Lesser 2001 ). The NWCA is based on that research. Wardrop et al. ( 2007a, b ), Stevens Jr.At a larger scale, Nestlerode et al. ( 2009, 2014 ) report on an assessment of Gulf of Mexico coastal wetlands. Wardrop et al. ( 2013 ) describe the evolution of monitoring and assessment in the Mid-Atlantic, culminating in an assessment of wetlands in the region. These studies used unequal probability survey designs, investigated potential indicators of wetland condition, and demonstrated the technical capability for conducting wetland assessments at the scale of a watershed and larger.http://hillstromplasticsurgery.com/images/96-mercury-sable-manual.pdf At the same time, state wetland programs were also testing and implementing wetland assessment efforts. The State of Minnesota is particularly noteworthy because it has employed a probability design to assess the quantity and quality of its wetlands (Genet and Olsen 2008, Genet 2012 ). This work was augmented by a state-wide assessment of wetland condition implemented as part of the 2011 NWCA and used a two-phase probability design (Minnesota Pollution Control Agency 2015 ). This paper describes the 2011 NWCA probability survey design, including its implementation and statistical estimation procedures. Since the geographic information system spatial coverage of wetland polygons (i.e., the sample frame) may not always correctly identify the wetlands included in the NWCA, the paper provides estimates of the proportion of the sample frame wetland area that is included in the NWCA. Finally, all wetlands included in the NWCA may not be able to be sampled either due to landowners denying field crews access to the wetland or due to the inaccessibility of the wetland site related to field crew safety or excessive time or cost required to do the assessment. The information from the evaluation status of the sites is used to estimate the proportion of the NWCA wetlands that could be sampled (i.e., the sampled population). Methods Study design The wetland types included in the NWCA (i.e., the target population) include all tidal and non-tidal wetlands within the conterminous USA with rooted vegetation and when present, shallow open water less than 1 m in depth that is not currently being used in the production of crops. A wetland’s jurisdictional status under state or federal regulatory programs does not factor into the NWCA wetland-type definition. Typically, intertidal categories occur in deeper water or are unlikely to contain rooted vegetation. This enables estimates to be made for all wetlands of interest based on the results of the sample. Survey designs have some inherent characteristics that distinguish them from other sampling designs. First, the population being sampled (target population) is explicitly described. Second, every element in the population has the opportunity to be sampled with known probability that is greater than 0. Third, the selection process includes an explicit random element. The NWCA wetland target population is viewed as a continuous resource; that is, wetlands are considered areal features. Any attribute of the wetland population, such as ecological condition, is assumed to vary continuously across the wetland. Consequently, the unit sampled is a site defined as a point where each attribute measured has a field plot design supporting its measurement. The plot design is described in detail in the NWCA 2011 Field Operations Manual (US EPA 2011 ). Sample frame Preferably, a national geographic data layer that included polygons representing wetlands in the target population (i.e., the sample frame) would be available and used to select sample sites. When the survey design for NWCA was required, no such sample frame was available. This provides a nationally consistent set of wetland polygons based on current imagery. Ohio elected to base their survey design on a current digital map of wetlands in Ohio. Minnesota has a Wetland Status and Trends Monitoring Program (WSTMP) that assesses the status and trends of wetland quantity and quality in Minnesota (Kloiber 2010 ). Each 4-mi 2 grid cell was subdivided into four 1-mi 2 grid cells. To be included in the design, at least 25 of a grid cell must be within the state. These polygons constitute the NWCA sample frame for Minnesota. Objectives included requirements to report on wetland condition nationally for seven wetland types, to report on nine NARS aggregated Omernik ecoregions, and to ensure that each of the states had a minimum of eight wetland sites to monitor. The random selection of the sites was completed in two steps (or phases) with the final inclusion probabilities being the product of the first step inclusion probability and the second step inclusion probability (which is conditional on the first step). In the next step, a Generalized Random Tessellation Stratified (GRTS) survey design for an area resource was applied to the wetland polygons (Stevens Jr.Since guaranteeing the exact number of sites by wetland type was not important and classification of the wetland type in the sample frame was not perfect, unequal inclusion probabilities were used within a state. For the NWCA, the expected sample size was 900 sites for the conterminous 48 states, although states had the option of sampling additional sites. This approach ensured that the sample size for the seven wetland types was sufficient for national reporting and that each state received a minimum number of sites (which also improved the national spatial balance of the sites). It also ensured the proportional allocation the sites by area within a wetland type. Site selection was completed using the R package “spsurvey” (Kincaid and Olsen 2015 ). The total number of site visits was 996 allocated to 900 unique sites with 96 sites to be revisited (two per state). To ensure that a sufficient number of sites were available that could be sampled, an additional 900 sites, as an over-sample, were selected to provide replacement sites for those sites that either are not part of the target population or could not be sampled (permission to sample not given by the landowner or site was not able to be sampled due to other access issues). To ensure that the final set of sites evaluated satisfied the requirements for a probability survey design, the sites were ordered in reverse hierarchical order (Stevens Jr.Three states elected to modify the survey design for their state. The state modifications replaced the above survey design for their state. In each case, the state designs identified sites that were required for the NWCA and additional sites that were specific to the state to meet state requirements. Wisconsin elected to study the Southeastern Plains Till region (Omernik and Griffith 2014 ). For the NWCA survey, the Wisconsin state stratum was replaced by a new design that included two strata, the Southeastern Plains Till region and the rest of the state. The sites selected under the national NWCA design were used for the rest of Wisconsin state region, and a new GRTS unequal probability survey design of 50 sites was selected for the Southeastern Plains Till region. Ohio elected to base their survey design on a current digital map of wetlands in Ohio ( ). A sample of size 50 was selected using an areal GRTS unequal probability survey design. Minnesota elected to base their survey design on mapped wetlands in the 1-mi 2 WSTMP plots. The next step was to select 150 sample sites using a GRTS unequal probability survey design from the delineated wetland polygons. The Minnesota sites required for the NWCA were the first 22 sites that were sampled when ordered by their site identification. An additional 150 sites were selected for use if any of the initial 150 sites could not be sampled, using the same process described earlier. Wetland evaluation and field sampling A critical element in the implementation of the survey design is the determination of the status of each site in the sample relative to the requirements of the design. Each site was checked to determine if it met the target population definition of a wetland included in the study. Where possible, the determination was made without a site visit; however, field reconnaissance was necessary for some evaluations. Initially, sites were screened using aerial photo interpretations to identify locations that did not meet the target population definition (e.g., non-NWCA wetland types, wetlands converted to non-wetland land cover due to development). Two other situations resulted in a wetland site not being sampled. First, many wetlands are on private land and require landowner permission to access. All landowner refusals were documented and recorded. When logistical or safety constraints made a wetland site inaccessible, the reason was recorded. Calculating the sample weights A critical activity for analyzing data from a study with a stratified, unequal probability survey design is deriving the weights for each of the evaluated sites. For this study, wetland area was used to determine the inclusion probability for each site. All statistical analyses used the weights based on the inclusion probability for each site, i.e., the inverse of its inclusion probability. Initial weights were calculated for each site based on the unequal inclusion probabilities used to select the sites based on the design. Since the site selection involved two steps, the initial weights are the product of the weights from the first step of selecting 4-mi 2 plots and the weights from the second step of selecting sites from wetland polygons identified in the selected 4-mi 2 plots. Final weights are equal to the total stratum area divided by the total area of the plots selected. This is an approximation of the number of 4-mi 2 plots in the stratum divided by the number of 4-mi 2 plots selected in the stratum. This is required since the plots are not all 4-mi 2 plots due to state boundaries. Weights for the second step are then adjusted by state and are equal to the initial weight for a site multiplied by the ratio of the total wetland acres in the 4-mi 2 plots within the state divided by the sum of the initial weights for all sites evaluated within the state. This adjustment accounts for the use of additional sites evaluated when the initial sites could not be sampled for various reasons and the requirement that each state sampled the number of sites specified by the design. Population estimation Information from the wetland site evaluation process was used to estimate the number of acres of wetlands in the target population for NWCA. The site evaluation information from sites determined to be target wetlands (whether sampled or not) was used to estimate the acres of wetlands that would not be sampleable (landowner denial or physically inaccessible) if they were selected. Finally, the site evaluation information from sites determined to be non-target for NWCA was used to investigate deficiencies of the sample frame. Diaz-Ramos et al. ( 1996 ) describe the statistical procedure used to produce these estimates. For calculating margins of error for these estimates, we used a variance estimate called a local neighborhood variance estimate, appropriate for spatially balanced survey designs, developed by Stevens Jr.In most cases, the local neighborhood variance estimator yields confidence interval coverage closer to the expected coverage than the standard Horvitz-Thompson variance estimator, which is typically used in complex, variable-probability survey designs (Stevens Jr. Results To sample 967 sites in the field, 2313 sites were evaluated (Fig. 1 ) to determine whether the sites met the definition of a wetland for the NWCA 2011, and if it met the definition, whether the site could be sampled. The 967 sites included additional sites from Wisconsin and Ohio who used NWCA field protocols for their state surveys, so that their data could be used for NWCA 2011. The survey design was intended to report by three and nine aggregated ecoregions. Limitations in the number of sites available for the development of the vegetation index and availability of reference wetlands reduced the number of geographic regions and wetland classes for which wetland results could be reported. In the West, reduced sample size was also a factor limiting the number of reporting categories. In addition, estuarine wetlands are reported only nationally (ALL). The classes used were woody wetlands in palustrine, shallow riverine, or shallow lacustrine littoral settings (PRLW) combining PSS—shrub and PFO—forested; herbaceous wetlands in palustrine, shallow riverine, or shallow lacustrine littoral settings (PRLH) combining PEM—emergent, PUBPAB—open-water ponds and aquatic bed, and Pf—farmed wetlands not in current crop production; and the original estuarine wetland types of estuarine herbaceous wetlands consisting of E2EM wetlands (EH) and estuarine woody wetlands consisting of E2SS wetlands (EW). Landowner denial of access to sample a wetland site is the primary reason 1644 target sites had to be evaluated to obtain 967 sampled sites. Rather, estimates based on the weights must be used to estimate the quality of the sample frame. Error bars are 95 confidence intervals Not all of the estimated target population acres could be sampled due to accessibility and field issues. The vertical line in panel a at 65 is the national percent of the target population estimated to be the sampled population. Similarly, 25 and 7 vertical lines in panels b and c are the national percent of the target population that is estimated to have landowners deny access ( b ) or to be physically inaccessible due to effort ( c ). That is, why was a site non-target for the NWCA 2011. Error bars are 95 confidence intervals Discussion The NWCA 2011 survey design was successful in enabling national and regional estimates of wetland condition to be made. Regional reporting consisted of ten reporting units based on a combinations of four ecoregions and four aggregated wetland types (palustrine, riverine, lacustrine herbaceous and woody, and estuarine herbaceous and woody). Also, only having approximately 5000 4-mi 2 plots available as the base of the NWCA design resulted in some clustering of sites within the plots. A sufficient number of wetland polygons for each wetland type were simply not available. This led to reducing the number of geographic regions and wetland types for reporting purposes. Each of these plots was then populated with the wetland polygons from the US FWS national digital map data ( ). While the national digital map data is complete, it is compiled from the latest existing state-level wetland mapping effort. In many cases, the data are not current, are dominated by information from the 1970s and 1980s, and are mapped at different scales. While this is not ideal, it improves the wetland sample frame, particularly in the West, and likely includes more wetlands than are currently present due to the loss of wetland area since the 1970s. Wetlands constructed since the digital map data from a state was updated will be missing, leading to constructed wetlands being potentially under represented. The more detailed classification used in the USFWS national digital map data enabled a more careful matching of wetland types to the NWCA wetland types. Overall, incorporation of the national digital map data improves the sample frame coverage of the NWCA target population and better meets the survey design requirement for geographic reporting units. While this resolves the issue of having more wetland sites in the west, it does so by giving up having current wetland polygon information. This results in the exclusion of newly constructed wetlands and possibly additional site evaluation due to wetlands disappearing, since the maps were constructed. The reason for being non-target would differ by NWCA wetland type. Given that a site would be evaluated as an NWCA wetland type, approximately 40 of the time the site would not be able to be sampled. The main reasons would be denial of access by landowner and the excessive physical effort necessary to reach the wetland site. The NWCA sample frame correctly identified the NWCA wetland type 82 of the time. Farmed wetlands (20) and open water ponds and aquatic bed wetlands (42) were the only two wetland types that were not well identified. In the former case, most were actively cropped wetlands, and in the latter, most had surface water too deep to meet the definition of a wetland. Given that wetland type within a state was ignored when selecting replacement sites, the impact was that not as many of these two wetland types were sampled as expected. It also resulted in additional costs due to the effort necessary to complete the site evaluations of the non-target wetland sites. Nationally, 65 of the NWCA wetland-type target population was estimated to be sampleable, 25 was estimated non-sampleable due to landowner access denial, and 7 was estimated to be physically inaccessible. Wetlands that were physically inaccessible may be more likely to have less local anthropogenic stressors; consequently, they may more likely be in better condition than wetlands that are accessible. While this may be a potential source of bias in the percent of the target population that was in good condition, the impact will be minimal given the small percent (7) that were inaccessible. Landowner access denial may have a greater impact due to the percent of access denial (25) and due to private landowners being the source of the denials. PRL-W wetlands in Coastal Plains and Eastern Mountains and Upper Midwest had the most wetland acres with landowner denials (approximately 10 and 3 million acres, respectively). PRL-H wetlands in West, Interior Plains, and Coastal Plains regions were next (approximately 3 million acres each) with the West having the highest landowner denial rate (57). Whether this results in any potential bias depends on whether wetlands associated with private landowners who deny access differ from wetlands associated with landowners who grant access. Note that Stevens Jr.While 65 of the target population being sampled for NWCA 2011 is lower than for National Aquatic Resource Surveys of streams, lakes, and coastal waters (US EPA 2009, 2015, 2016 ), estimates of condition for the sampled population remain valid, although a potential bias in the estimates exists if the results are inappropriately assumed to apply to the target population of NWCA wetland types. Acknowledgments Michael E. Scozzafava and Gregg Serenbetz of the US Environmental Protection Agency’s (US EPA) Wetlands Division led the development of the NWCA and without their leadership this paper would not have been possible. The manuscript has been subjected to review by the Western Ecology Division of ORD’s National Health and Environmental Effects Research Laboratory and approved for publication. Approval does not signify that the contents reflect the views of the Agency, nor does mention of trade names or commercial products constitute endorsement or recommendation for use. The data from the 2011 NWCA used in this paper resulted from the collective efforts of dedicated field crews, laboratory staff, data management and quality control staff, analysts, and many others from EPA, states, tribes, federal agencies, universities, and other organizations. Footnotes This article is part of the Topical Collection on Monitoring Wetlands on a Continental Scale: The Technical Basis for the National Wetland Condition Assessment Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. References R Core Team. (2015). R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.. Cowardin LM, Carter V, Golet FC, LaRoe ET. Classification of wetlands and deepwater habitats of the United States. Status and trends of wetlands in conterminous United States 1986 to 1997. Status and trends of wetlands in the conterminous United States 1998 to 2004. Status and trends of wetlands in the conterminous United States 2004 to 2009. Technical procedures for conducting status and trends of the nation’s wetlands. EMAP statistics methods manual. Evaluation of US environmental monitoring and assessment program’s (EMAP)—wetlands sampling design and classification. Assessment of wetlands in the Cuyahoga River watershed of northeast Ohio. Saint Paul, MN: Minnesota Pollution Control Agency. Developing an index of wetland condition from ecological data: an example using HGM functional variables from the Nanticoke watershed, USA. R package version 3.1. URL:. Kloiber SM. Status and trends of wetlands in Minnesota: wetland quantity baseline. Evaluation of EMAP—wetlands sampling design using national wetlands inventory data. Application of a three-tier framework to assess ecological condition of Gulf of Mexico coastal wetlands. Monitoring design and extent estimates for national. In: Gitzen RA, Millspaugh JJ, Cooper AB, Licht DS, editors. Design and analysis of long-term ecological monitoring studies. Ecoregions of the conterminous United States. Ecoregions of the conterminous United States: evolution of a hierarchical spatial framework. Survey design and extent estimates for the National Lakes Assessment. Variance estimation for spatially balanced samples of environmental resources. Spatially-balanced sampling of natural resources. Coastal wetlands indicator study: EMAP-Estuaries Louisianian Province—1991. National lakes assessment: a collaborative survey of the nation’s lakes. National Wetland Condition Assessment 2001: field operations manual. National Coastal Condition Assessment 2010. Monitoring and assessment of wetlands: concepts, case studies, and lessons learned. In: Brooks RP, Wardrop DH, et al., editors. Mid-Atlantic freshwater wetlands: advances in wetlands science, management, policy, and practice. Not a MyNAP member yet. Register for a free account to start saving and receiving special member only perks.