A map service depicting Bailey's ecoregions and ecosystems of regional extent in the United States, Puerto Rico, and the U.S. Virgin Islands, based on conditions in 1994. Four levels of detail are included to show a hierarchy of ecosystems. The largest ecosystems are domains, which are groups of related climates and which are differentiated based on precipitation and temperature. Divisions represent the climates within domains and are differentiated based on precipitation levels and patterns as well as temperature. Divisions are subdivided into provinces, which are differentiated based on vegetation or other natural land covers. The finest level of detail is described by subregions, called sections, which are subdivisions of provinces based on terrain features. Also identified are mountainous areas that exhibit different ecological zones based on elevation. Also included are maps of the Bailey Ecoregions of the United States in multiple formats and sizes. Metadata and Downloads

This map is commonly called Bailey's ecoregions and shows ecosystems of regional extent in the United States, Puerto Rico, and the U.S. Virgin Islands, based on conditions in 1994. Four levels of detail are included to show a hierarchy of ecosystems. The largest ecosystems are domains, which are groups of related climates and which are differentiated based on precipitation and temperature. Divisions represent the climates within domains and are differentiated based on precipitation levels and patterns as well as temperature. Divisions are subdivided into provinces, which are differentiated based on vegetation or other natural land covers. The finest level of detail is described by subregions, called sections, which are subdivisions of provinces based on terrain features. Also identified are mountainous areas that exhibit different ecological zones based on elevation. Also included are maps of the Bailey Ecoregions of the United States in multiple formats and sizes.

This multi-tiered, broad-scale, hierarchical system of ecoregions is based on numerous environmental variables at each level. The first two tiers are based on climate, followed by climate and physiograpghy, and finally topography and soils. This data was used to provide a general description of the ecosystem geography.

Bailey's Ecoregions of the World (1989)

Analysis of ‘Bailey's Ecoregions and Subregions Dataset’ provided by Analyst-2 (analyst-2.ai), based on source dataset retrieved from https://catalog.data.gov/dataset/8b68912e-b005-486f-99c2-1baef33c44e8 on 11 February 2022.

--- Dataset description provided by original source is as follows ---

This map is commonly called Bailey's ecoregions and shows ecosystems of regional extent in the United States, Puerto Rico, and the U.S. Virgin Islands, based on conditions in 1994. Four levels of detail are included to show a hierarchy of ecosystems. The largest ecosystems are domains, which are groups of related climates and which are differentiated based on precipitation and temperature. Divisions represent the climates within domains and are differentiated based on precipitation levels and patterns as well as temperature. Divisions are subdivided into provinces, which are differentiated based on vegetation or other natural land covers. The finest level of detail is described by subregions, called sections, which are subdivisions of provinces based on terrain features. Also identified are mountainous areas that exhibit different ecological zones based on elevation. Also included are maps of the Bailey Ecoregions of the United States in multiple formats and sizes.

--- Original source retains full ownership of the source dataset ---

The purpose of the work, which began in 1976, was to show how the national forests of the United States fit within the global ecoregional scheme. In this system an ecoregion is defined as any large portion of the Earth's surface over which the ecosystems have characteristics in common. There are three levels in this classification system, the Domains, the Divisions and the Provinces.Ecoregions of the continents are based on macroclimate (i.e., the climate that lies just beyond the local modifying irregularities of landform and vegetation). The theory behind the approach is that macroclimates are among the most significant factors affecting the distribution of life on Earth. As the macroclimate changes, the other components of the ecosystem change in response. Macroclimates influence soil formation and help shape surface topography, as well as affecting the suitability for human habitation.Four Domains were defined: Polar, Humid temperate, Humid tropical and Dry. The combination of temperature and rainfall to indicate major climatic zones was based on Köppen and Trewartha's work, where dry climates were treated as a separate entity from Tropical humid and Temperate humid. However, the Köppen system defines an addtional "Subtropical" division at this level.The next level in the Bailey system is the Divisions, and these are also climate - based, for example in the Humid temperate Domain there is Hot continental, Warm continental, Subtropical, Marine, Prairie and Mediterranean, all with Mountain variants (i.e., a total of 12 Divisions in this Domain). There are a total of 30 of these.The third and last level are the Provinces, which are based on physiognomy of vegetation, modified by climate. For example, the Forest-Meadow of Eastern Oceanic (Monsoon climate). There are a total of 98 of these subdivisions.The global map has been digitised and converted to a geographic (lat/long) projection by the WCMC, Cambridge, UK. It is also available on CD from NOAAs National Geophysical Data Center in Boulder, Colorado as part of their Global Ecosystem Database Project. http://www.ngdc.noaa.gov/Store/.

This package consists of a geo-spatial data file, specifically, an ESRI polygon shape file, containing approximately 1700 polygons depicting the Bailey's Eco Regions classification system. (Consult http://www.nationalatlas.gov/mld/ecoregp.html for a summary of this system). Also included is an R-language script that applies a regularly-spaced point grid on top of the polygon map, and produces a geospatial point file containing samples of the Bailey's region code at each point in the grid.

Ths data set consists Bailey's Ecoregions polygons for the continental United States, sampled into raster grids at spatial resolutions of .1 and 1.0 degrees.

Baileys Ecoregions - Subregions by DomainThis feature layer, utilizing National Geospatial Data Asset (NGDA) data from the U.S. Forest Service (USFS), displays ecosystems by domains in the United States, Puerto Rico and the U.S. Virgin Islands. Per the USFS, "the largest ecosystems are domains, which are groups of related climates and which are differentiated based on precipitation and temperature".Humid Temperate Domain & Humid Tropical DomainData currency: This cached Esri federal service is checked weekly for updates from its enterprise federal source (Bailey's Ecoregions by Domain) and will support mapping, analysis, data exports and OGC API – Feature access.Data.gov: Bailey's Ecoregions and Subregions DatasetGeoplatform: Bailey's Ecoregions and Subregions DatasetOGC API Features Link: (Baileys Ecoregions - Subregions by Domain - OGC Features) copy this link to embed it in OGC Compliant viewersFor more information, please visit: Description of the Ecoregions of the United States For feedback please contact: Esri_US_Federal_Data@esri.comThumbnail image courtesy of: Bureau of Land ManagementNGDA Data SetThis data set is part of the NGDA Biodiversity Theme Community. Per the Federal Geospatial Data Committee (FGDC), Biodiversity is defined as pertaining to, or describing, "the dynamic processes, interactions, distributions, and relationships between and among organisms and their environments".For other NGDA Content: Esri Federal Datasets

This is the master spatial data layer for TNC's terrestrial ecoregions of the world, exported from the geodatabase listed above. Note that it includes Mangroves, Inland Water, and Rock and Ice MHTs, although they are not being handled by terrestrial assessments. This layer is based on WWF's ecoregions outside the United States, and loosely based on Bailey's ecoregions (from the USDA Forest Service) within the United States.Purpose: Developed originally by Olson, D. M. and E. Dinerstein (2002), Bailey (1995) and Environment Canada (Wiken, 1986), these data layers were modified by The Nature Conservancy (TNC) to be used in its Biodiversity Planning exercises in the process known as Ecoregional Assessments. Several Ecoregions were modified from the originals by TNC staff developing the aforementioned assessments. The modifications are based on ecological, bio-physical and political rationales; most changes are noted in the accompanying documentation (attributes). Ecoregions in Canada and Mexico were modified mainly at the border with US territory, where TNC modified-Bailey (1995) ecoregions crossed over the country boundaries and the Olson, D. M. and E. Dinerstein (2002) and (Wiken, 1986) were replaced where the TNC modified-Bailey (1995) overlayed them. This layer was split from the terrestrial ecoregional assessment layer in June 2008.

We assessed the geophysical settings within the larger context of natural ecoregions. Ecoregions are large contiguous units of land with similar environmental conditions (landforms, geology, and soils) which share a similar climate and a distinct assemblage of natural communities and species. The term “ecoregion" was coined by J.M. Crowley (1967) and later popularized by Robert Bailey of the US Forest Service (Bailey 1995). In recent decades, ecoregions have become a defining construct of larger conservation efforts because they provide an ecological context for understanding landscape-scale conservation activities by enabling the evaluation of properties considered critical to conserving biodiversity such as representation, complementarity, redundancy, ecological function, and endemism. The TNC ecoregions used for this analysis are modified from Bailey (1995) and were based on the subsections delineated by the U.S. Forest Service (USDA Forest Service ECOMAP Team 2007) and the Canadian Provinces (Ecological Stratification Working Group 1995). In comparison to Bailey’s ecoregions, TNC’s grouping of subsections puts more emphasis on physical characteristics and natural communities and less on climatic patterns.We made two changes to the ecoregions based on steering committee feedback.The boundary between the Tropical Florida and the Florida Peninsula ecoregions was not satisfactory with a number of science staff in Florida. The Peninsula Florida ecoregion extended southward along the Florida Gulf of Mexico and Atlantic Ocean coasts while Eastern Terrestrial Resilience Update 186 | Page it bowed northward at the interior of the Florida Peninsula. This ignored the temperature moderating effect of the Gulf and the ocean, making the climate warmer along the coast further to the north in Florida. The upward pointing bow, it was felt, should actually be a downward pointing bow. To model this desired new boundary between the two ecoregions, climate data was acquired from the Prism Climate Group of the Northwest Alliance for Computational Science and Engineering.TNC’s grouping of subsections puts more emphasis on physical characteristics and natural communities and less on climatic patterns. We made a revision to then ecoregions for this analysis which was to update the border between the Upper West Gulf Coastal Plain and the Mississippi River Alluvial Plain to the EPA Level III linework (US Environmental Protection Agency 2013) which more closely matched the landform patterns along that edge section.

This polygon shapefile depicts global ecoregions, major habitat types, biogeographical realms and The Nature Conservancy terrestrial assessment units as of December 14, 2009. Developed originally by Olson, D. M. and E. Dinerstein (2002), Bailey (1995) and Environment Canada (Wiken, 1986), these data layers were modified by The Nature Conservancy (TNC) to be used in its Biodiversity Planning exercises in the process known as Ecoregional Assessments. Several Ecoregions were modified from the originals by TNC staff developing the aforementioned assessments. The modifications are based on ecological, bio-physical and political rationales; most changes are noted in the accompanying documentation (attributes). Ecoregions in Canada and Mexico were modified mainly at the border with US territory, where TNC modified-Bailey (1995) ecoregions crossed over the country boundaries and the Olson, D. M. and E. Dinerstein (2002) and (Wiken, 1986) were replaced where the TNC modified-Bailey (1995) overlayed them. This layer was split from the terrestrial ecoregional assessment layer in June 2008.

Ecoregions denote areas of general similarity in ecosystems and in the type, quality, and quantity of environmental resources. They are designed to serve as a spatial framework for the research, assessment, management, and monitoring of ecosystems and ecosystem components. These general purpose regions are critical for structuring and implementing ecosystem management strategies across federal agencies, state agencies, and nongovernment organizations that are responsible for different types of resources within the same geographical areas. The approach used to compile this map is based on the premise that ecological regions can be identified through the analysis of patterns of biotic and abiotic phenomena, including geology, physiography, vegetation, climate, soils, land use, wildlife, and hydrology. The relative importance of each characteristic varies from one ecological region to another. A Roman numeral hierarchical scheme has been adopted for different levels for ecological regions. Level I is the coarsest level, dividing North America into 15 ecological regions. Level II divides the continent into 50 regions (Commission for Environmental Cooperation Working Group, 1997). At Level III, the continental United States contains 104 regions whereas the conterminous United States has 85 (U.S. Environmental Protection Agency, 2005). Level IV ecoregions are further subdivisions of Level III ecoregions. Methods used to define the ecoregions are explained in Omernik (1995, 2004), Omernik and others (2000), and Gallant and others (1989). Data Download: https://app.fw.ky.gov/kfwis/kygeonet/ecoregion2012.zip Literature cited: Bailey, R.G., Avers, P.E., King, T., and McNab, W.H., eds., 1994, Ecoregions and subregions of the United States (map): Washington, D.C., USFS, scale 1:7,500,000.Bryce, S.A., Omernik, J.M., and Larsen, D.P., 1999, Ecoregions—a geographic framework to guide risk characterization and ecosystem management: Environmental Practice, v. 1, no. 3, p. 141-155.Commission for Environmental Cooperation Working Group, 1997, Ecological regions of North America- toward a common perspective: Montreal, Commission for Environmental Cooperation, 71 p. Gallant, A. L., Whittier, T.R., Larsen, D.P., Omernik, J.M., and Hughes, R.M., 1989, Regionalization as a tool for managing environmental resources: Corvallis, Oregon, U.S. Environmental Protection Agency, EPA/600/3-89/060, 152p. Griffith, G., Omernik, J., Azevedo, S., 1998, Ecoregions of Tennessee (text, map, summary tables, and photographs): Reston, Virginia, U.S. Geological Survey, map scale 1:940,000.McMahon, G., Gregonis, S.M., Waltman, S.W., Omernik, J.M., Thorson, T.D., Freeouf, J.A., Rorick, A.H., and Keys, J.E., 2001, Developing a spatial framework of common ecological regions for the conterminous United States: Environmental Management, v. 28, no. 3, p. 293-316.Omernik, J.M., 1987, Ecoregions of the conterminous United States (map supplement): Annals of the Association of American Geographers, v. 77, p. 118-125, scale 1:7,500,000.Omernik, J.M., 1995, Ecoregions - a framework for environmental management, in Davis, W.S. and Simon, T.P., eds., Biological assessment and criteria-tools for water resource planning and decision making: Boca Raton, Florida, Lewis Publishers, p.49-62. Omernik, J.M., Chapman, S.S., Lillie, R.A., and Dumke, R.T., 2000, Ecoregions of Wisconsin: Transactions of the Wisconsin Academy of Science, Arts, and Letters, v. 88, p. 77-103.Omernik, J.M., 2004, Perspectives on the nature and definitions of ecological regions: Environmental Management, v. 34, Supplement 1, p. s27-s38.U.S. Department of Agriculture–Soil Conservation Service, 198, Land resource regions and major land resource areas of the United States: Agriculture Handbook 296, 156 p.U.S. Environmental Protection Agency, 2002, Level III ecoregions of the continental United States (revision of Omernik, 1987): Corvallis, Oregon, USEPA–National Health and Environmental Effects Research Laboratory, Map M-1, various scales.Wiken, E., 1986, Terrestrial ecozones of Canada: Ottawa, Environment Canada, Ecological Land Classification Series no. 19, 26 p.Woods, A.J., Omernik, J.M., Brockman, C.S., Gerber, T.D., Hosteter, W.D., and Azevedo, S.H., 1998, Ecoregions of Indiana and Ohio: Reston, USGS, map scale 1:500,000Comments and questions regarding the Level III and IV Ecoregions should be addressed to Glenn Griffith, USGS, c/o US EPA., 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4465, email:griffith.glenn@epa.gov Alternate: James Omernik, USGS, c/o US EPA, 200 SW 35th Street, Corvallis, OR 97333, (541)-754-4458, email:omernik.james@epa.govThis was first downloaded by KDFWR in 2005 for the State Wildlife Action Plan and then updated in 2012 again to reflect an updated national shapefile. Kentucky Department of Fish and Wildlife Resources downloaded first the Kentucky Data set https://www.epa.gov/eco-research/ecoregion-download-files-state-region-4#pane-15 , but saw that the boundary did match well the Kentucky state boundary maintained by KY Geonet. We then downloaded the national data set obtained from https://www.epa.gov/eco-research/level-iii-and-iv-ecoregions-continental-united-statesand intersected to the KY DGI state boundary, For those slivers assigned to unexpected ecoregions (55d Pre-Wisconsinan Drift Plains, 67h Southern Sandstone Ridges, 71m Northern Shawnee Hills, 71n Southern Shawnee Hills, 73c St. Francis Lowlands) we merged to the geographically nearest polygon so that the ecoregions found in this dataset match that in the poster Ecoregions of Kentucky.

Based on: Global Ecoregions, Major Habitat Types, Biogeographical Realms and The Nature Conservancy Terrestrial Assessment Units as of December 14, 2009. Developed originally by Olson, D. M. and E. Dinerstein (2002), Bailey (1995) and Environment Canada (Wiken, 1986), and modified by The Nature Conservancy (TNC). Ecoregions are relatively large units of land containing distinct assemblages of natural communities and species, with boundaries that approximate the original extent of natural communities prior to major land-use change. Ecoregions are nested within two higher-order classifications: biomes (14) and biogeographic realms (8). Source: WWF

This dataset can be used to identify the outline of California's ecological provinces and regions.

On the continental scale, climate is an important determinant of the distributions of plant taxa and ecoregions. To quantify and depict the relations between specific climate variables and these distributions, we placed modern climate and plant taxa distribution data on an approximately 25-kilometer (km) equal-area grid with 27,984 points that cover Canada and the continental United States (Thompson and others, 2015). The gridded climatic data include annual and monthly temperature and precipitation, as well as bioclimatic variables (growing degree days, mean temperatures of the coldest and warmest months, and a moisture index) based on 1961-1990 30-year mean values from the University of East Anglia (UK) Climatic Research Unit (CRU) CL 2.0 dataset (New and others, 2002), and absolute minimum and maximum temperatures for 1951-1980 interpolated from climate-station data (WeatherDisc Associates, 1989). As described below, these data were used to produce portions of the "Atlas of relations between climatic parameters and distributions of important trees and shrubs in North America" (hereafter referred to as "the Atlas"; Thompson and others, 1999a, 1999b, 2000, 2006, 2007, 2012a, 2015). Evolution of the Atlas Over the 16 Years Between Volumes A & B and G: The Atlas evolved through time as technology improved and our knowledge expanded. The climate data employed in the first five Atlas volumes were replaced by more standard and better documented data in the last two volumes (Volumes F and G; Thompson and others, 2012a, 2015). Similarly, the plant distribution data used in Volumes A through D (Thompson and others, 1999a, 1999b, 2000, 2006) were improved for the latter volumes. However, the digitized ecoregion boundaries used in Volume E (Thompson and others, 2007) remain unchanged. Also, as we and others used the data in Atlas Volumes A through E, we came to realize that the plant distribution and climate data for areas south of the US-Mexico border were not of sufficient quality or resolution for our needs and these data are not included in this data release. The data in this data release are provided in comma-separated values (.csv) files. We also provide netCDF (.nc) files containing the climate and bioclimatic data, grouped taxa and species presence-absence data, and ecoregion assignment data for each grid point (but not the country, state, province, and county assignment data for each grid point, which are available in the .csv files). The netCDF files contain updated Albers conical equal-area projection details and more precise grid-point locations. When the original approximately 25-km equal-area grid was created (ca. 1990), it was designed to be registered with existing data sets, and only 3 decimal places were recorded for the grid-point latitude and longitude values (these original 3-decimal place latitude and longitude values are in the .csv files). In addition, the Albers conical equal-area projection used for the grid was modified to match projection irregularities of the U.S. Forest Service atlases (e.g., Little, 1971, 1976, 1977) from which plant taxa distribution data were digitized. For the netCDF files, we have updated the Albers conical equal-area projection parameters and recalculated the grid-point latitudes and longitudes to 6 decimal places. The additional precision in the location data produces maximum differences between the 6-decimal place and the original 3-decimal place values of up to 0.00266 degrees longitude (approximately 143.8 m along the projection x-axis of the grid) and up to 0.00123 degrees latitude (approximately 84.2 m along the projection y-axis of the grid). The maximum straight-line distance between a three-decimal-point and six-decimal-point grid-point location is 144.2 m. Note that we have not regridded the elevation, climate, grouped taxa and species presence-absence data, or ecoregion data to the locations defined by the new 6-decimal place latitude and longitude data. For example, the climate data described in the Atlas publications were interpolated to the grid-point locations defined by the original 3-decimal place latitude and longitude values. Interpolating the data to the 6-decimal place latitude and longitude values would in many cases not result in changes to the reported values and for other grid points the changes would be small and insignificant. Similarly, if the digitized Little (1971, 1976, 1977) taxa distribution maps were regridded using the 6-decimal place latitude and longitude values, the changes to the gridded distributions would be minor, with a small number of grid points along the edge of a taxa's digitized distribution potentially changing value from taxa "present" to taxa "absent" (or vice versa). These changes should be considered within the spatial margin of error for the taxa distributions, which are based on hand-drawn maps with the distributions evidently generalized, or represented by a small, filled circle, and these distributions were subsequently hand digitized. Users wanting to use data that exactly match the data in the Atlas volumes should use the 3-decimal place latitude and longitude data provided in the .csv files in this data release to represent the center point of each grid cell. Users for whom an offset of up to 144.2 m from the original grid-point location is acceptable (e.g., users investigating continental-scale questions) or who want to easily visualize the data may want to use the data associated with the 6-decimal place latitude and longitude values in the netCDF files. The variable names in the netCDF files generally match those in the data release .csv files, except where the .csv file variable name contains a forward slash, colon, period, or comma (i.e., "/", ":", ".", or ","). In the netCDF file variable short names, the forward slashes are replaced with an underscore symbol (i.e., "_") and the colons, periods, and commas are deleted. In the netCDF file variable long names, the punctuation in the name matches that in the .csv file variable names. The "country", "state, province, or territory", and "county" data in the .csv files are not included in the netCDF files. Data included in this release: - Geographic scope. The gridded data cover an area that we labelled as "CANUSA", which includes Canada and the USA (excluding Hawaii, Puerto Rico, and other oceanic islands). Note that the maps displayed in the Atlas volumes are cropped at their northern edge and do not display the full northern extent of the data included in this data release. - Elevation. The elevation data were regridded from the ETOPO5 data set (National Geophysical Data Center, 1993). There were 35 coastal grid points in our CANUSA study area grid for which the regridded elevations were below sea level and these grid points were assigned missing elevation values (i.e., elevation = 9999). The grid points with missing elevation values occur in five coastal areas: (1) near San Diego (California, USA; 1 grid point), (2) Vancouver Island (British Columbia, Canada) and the Olympic Peninsula (Washington, USA; 2 grid points), (3) the Haida Gwaii (formerly Queen Charlotte Islands, British Columbia, Canada) and southeast Alaska (USA, 9 grid points), (4) the Canadian Arctic Archipelago (22 grid points), and (5) Newfoundland (Canada; 1 grid point). - Climate. The gridded climatic data provided here are based on the 1961-1990 30-year mean values from the University of East Anglia (UK) Climatic Research Unit (CRU) CL 2.0 dataset (New and others, 2002), and include annual and monthly temperature and precipitation. The CRU CL 2.0 data were interpolated onto the approximately 25-km grid using geographically-weighted regression, incorporating local lapse-rate estimation and correction. Additional bioclimatic variables (growing degree days on a 5 degrees Celsius base, mean temperatures of the coldest and warmest months, and a moisture index calculated as actual evapotranspiration divided by potential evapotranspiration) were calculated using the interpolated CRU CL 2.0 data. Also included are absolute minimum and maximum temperatures for 1951-1980 interpolated in a similar fashion from climate-station data (WeatherDisc Associates, 1989). These climate and bioclimate data were used in Atlas volumes F and G (see Thompson and others, 2015, for a description of the methods used to create the gridded climate data). Note that for grid points with missing elevation values (i.e., elevation values equal to 9999), climate data were created using an elevation value of -120 meters. Users may want to exclude these climate data from their analyses (see the Usage Notes section in the data release readme file). - Plant distributions. The gridded plant distribution data align with Atlas volume G (Thompson and others, 2015). Plant distribution data on the grid include 690 species, as well as 67 groups of related species and genera, and are based on U.S. Forest Service atlases (e.g., Little, 1971, 1976, 1977), regional atlases (e.g., Benson and Darrow, 1981), and new maps based on information available from herbaria and other online and published sources (for a list of sources, see Tables 3 and 4 in Thompson and others, 2015). See the "Notes" column in Table 1 (https://pubs.usgs.gov/pp/p1650-g/table1.html) and Table 2 (https://pubs.usgs.gov/pp/p1650-g/table2.html) in Thompson and others (2015) for important details regarding the species and grouped taxa distributions. - Ecoregions. The ecoregion gridded data are the same as in Atlas volumes D and E (Thompson and others, 2006, 2007), and include three different systems, Bailey's ecoregions (Bailey, 1997, 1998), WWF's ecoregions (Ricketts and others, 1999), and Kuchler's potential natural vegetation regions (Kuchler, 1985), that are each based on distinctive approaches to categorizing ecoregions. For the Bailey and WWF ecoregions for North America and the Kuchler potential natural vegetation regions for the contiguous United States (i.e.,

Climate envelopes dynamics within ecoregions of the US (Bailey 1995).

Link to landing page referenced by identifier. Service Protocol: Link to landing page referenced by identifier. Link Function: information-- dc:identifier.

This is a shapefile showing the ecoregions of the state of Nebraska as defined in conjunction with the development of a comprehensive wildlife conservation plan (Schneider et al 2005, aka the Natural Legacy Plan) for the state. The following description of the ecoregion layer and the sources of data used to create it were copied directly from Appendix 10 (page 246) of that document: Ecoregions are relatively large units of land and water delineated by the biotic and abiotic factors (e.g. climate, topography, geology, vegetation) that regulate the structure and function of the ecosystems within them. There are two main ecoregion maps for the United States, one developed by the U.S. Forest Service (Bailey et al. 1994) and the other developed by the U.S. Environmental Protection Agency (Omernik et al. 1987). For the Natural Legacy Project we delineated ecoregions using primarily Level III ecoregion lines from Ecoregions of Nebraska and Kansas (Chapman et al. 2001), which was a joint project of the USFS and EPA to blend the two systems. However, we used Bailey's Section level line to delineate the western boundary of tallgrass prairie south of the Sandhills since this was a better fit with Kaul and Rolfsmeier's (1993) map of the native vegetation of Nebraska.

The NPP Database contains documented field measurements of NPP for global terrestrial sites compiled from published literature and other extant data sources. The NPP Database contains biomass dynamics, climate, and site-characteristics data georeferenced to each intensive site. A major goal of the data compilation is to use consistent and standard well-documented methods to estimate NPP from the field data. Other important components of the database include a summary, investigator contact information, and a list of key references for each site. As far as possible, the original principal investigator or his/her successor has been contacted to review the data and documentation. The NPP Database currently contains detailed data for over 60 intensive study sites. A majority of these sites are grasslands, the remainder being tropical forests, boreal forests, and tundra study sites. Some combination of above-ground annual peak live biomass data and/or seasonal biomass dynamics data are available for all sites. Many sites also have data on below-ground biomass and/or turnover. Estimates of net primary productivity are included, where available, for individual sites, and as part of the NPP Summary tables. Climate and soils data are available for all sites in varying degrees of detail. The sites have been grouped according to vegetation maps based upon Bailey ecoregions, Holdridge Life-Zones, Matthews vegetation classes, and Olson World Ecosystem Complexes. Previously compiled multi-site data sets of georeferenced NPP estimates are also provided. NPP estimates are available from a number of different collections, containing more than 1700 sites but with less information available for each individual site as compared to the intensive sites. Records for these sites typically include an NPP value, latitude and longitude, original source of the data, and sometimes information on vegetation type, management, soils, and local climate. More information on the entire Net Primary Productivity Project can be found at the NPP home page, with links to further details on individual study sites or multi-site collections. Users are encouraged to browse these Web pages to find details of original studies, methodologies, and original research contacts. NPP data are available on-line from the ORNL Distributed Active Archive Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee, U.S.A. Data Citation: Cite the data sets using the following reference format: Author, P. A., and M. B. Author. Year. Data Set Title. Available on-line from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. For example: Williamson, P., and J. Pitman. 1999. NPP Grassland: Beacon Hill, U.K. 1972-1973. Available on-line from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.