Irwin and Bockstael 1010.1073/pnas.0705527105 |
Fig. 2. State of Maryland 2000 land use.
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| Percent change in land use (1973-2000) |
Low-density residential | Estimate (P value) | 0.139 (0.000) |
R 2 | 0.29 | |
Moran's I (P value) | -0.006 (0.350) | |
Medium- to high-density residential | Estimate (P value) | -0.038 (0.000) |
R 2 | 0.08 | |
Moran's I (P value) | -0.008 (0.306) | |
Nonresidential urban | Estimate (P value) | -0.012 (0.102) |
R 2 | 0.07 | |
Moran's I (P value) | -0.009 (0.342) | |
Undeveloped | Estimate (P value) | 0.093 (0.000) |
R 2 | 0.08 | |
Moran's I (P value) | -0.007 (0.290) |
Dependent variable = Difference in proportion of contrasting edges, 2000 - 1973 (2 ´ 2 km window); n = 2,007; inverse distance weighting function with maximum cut-off of 5,000 m; constant term included in each regression. Moran's I test for spatial autocorrelation estimated with residuals. P value determined by randomization with 499 permutations.
| Estimate | Standard error | z value | Probability |
Constant | 0.20224 | 0.02656 | 7.61 | 0.000 |
Distance to nearest urban center | 0.00599 | 0.00095 | 6.32 | 0.000 |
(Distance to nearest urban center)2 | -0.00004 | 0.00001 | -4.62 | 0.000 |
Distance to Chesapeake Bay coastline | 0.05726 | 0.01399 | 4.09 | 0.000 |
Distance to nearest major road | 0.00003 | 0.00002 | 1.78 | 0.075 |
Well suited for urban development (indicator) | 0.04593 | 0.01851 | 2.48 | 0.013 |
Poorly draining soils (indicator) | 0.06134 | 0.01796 | 3.42 | 0.001 |
Minimum lot size | 0.00709 | 0.00105 | 6.73 | 0.000 |
Spatial error correlation coefficient | 0.19313 | 0.03559 | 5.43 | 0.000 |
R 2 = 0.245 |
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Dependent variable = proportion of contrasting edges in 2000 within 2 ´ 2 km window; sample = windows that contained at least some development in 2000; n = 697; inverse distance weighting function with maximum cut-off of 5,000 m; Moran's I statistic with residuals = -0.0114; P value determined by randomization with 499 permutations = 0.372.
SI Appendix
Description of Data
The following provides a general description of the datasets used in the analyses. The basic information listed is from each of the metadata files that are associated with each of the datasets.
1973 Land Use/Land Cover for Maryland (MDP)
Data generation
Originating Agency: Maryland Department of Planning
Projection and Units: Maryland State Plane Coordinates - meters
Datum: NAD 1983
Minimum mapping unit: 10 acres
Developed using uncontrolled high altitude aerial photography and State Highway Administration 1" = 1 mile County Maps.
Original Collection (developed mid 1970s): Various land use categories were identified as polygons and displayed manually as ink on Mylar with number codes.
Digitization done in 2003
Additional considerations of 1973 data relative to 2000 Land Use/Land Cover:
(1) More interior water bodies (e.g., ponds) mapped in 2000 and not in 1973 resulting in an increase in water for 2000.
(2) National Wetland Inventory Data used in 2000 to confirm and refine the shape of wetland areas 5 acres or greater in size. These were not used in 1973, which resulted in more accurate mapping of wetlands for 2000.
(3) Minimum mapping unit in 1973: 10 acres; in 2000 additional data from MD Property View were used to refine urban land use categories, resulting in more refined mapping results.
(4) Some transportation features mapped in 2000 (particularly in Baltimore City) and not in 1973 resulting in a decrease in other land use categories in 1973
(5) Code 24 was originally used in 1973 and changed to either 241 or 242 for 2000, resulting in a more comparable dataset.
Land use classification
The land use/land cover classification scheme described below was used to identify the predominant usage of land that could be interpreted from high altitude, uncorrected aerial photography circa 1973. The LU_CODE field, in each county land use shape file, contains the 2 or 3 digit integer numbers identified below. Only land uses greater than 10 acres in size were identified when this map dataset was developed in the mid 1970s. Transportation features such as roads, highways, rail lines and utility lines were not included.
10 Urban Built-Up
11 Low-density residential - Detached single-family/duplex dwelling units, yards and associated areas. Areas of more than 90% single-family/duplex dwelling units, with lot sizes of less than five acres but at least one-half acre (.2 dwelling units/acre to 2 dwelling units/acre).
12 Medium-density residential - Detached single-family/duplex, attached single-unit row housing, yards, and associated areas. Areas of more than 90% single-family/duplex units and attached single-unit row housing, with lot sizes of less than one-half acre but at least one-eighth acre (2 dwelling units/acre to 8 dwelling units/acre).
13 High-density residential - Attached single-unit row housing, garden apartments, high-rise apartments/condominiums, mobile home and trailer parks. Areas of more than 90% high-density residential units, with more than 8 dwelling units per acre.
14 Commercial - Retail and wholesale services. Areas used primarily for the sale of products and services, including associated yards and parking areas.
15 Industrial - Manufacturing and industrial parks, including associated warehouses, storage yards, research laboratories, and parking areas.
16 Institutional - Elementary and secondary schools, middle schools, junior and senior high schools, public and private colleges and universities, military installations (built-up areas only, including buildings and storage, training, and similar areas), churches, medical and health facilities, correctional facilities, and government offices and facilities that are clearly separable from the surrounding land cover.
17 Extractive - Surface mining operations, including sand and gravel pits, quarries, coal surface mines, and deep coal mines. Status of activity (active vs. abandoned) is not distinguished.
18 Open urban land - Urban areas whose use does not require structures, or urban areas where non-conforming uses characterized by open land have become isolated. Included are golf courses, parks, recreation areas (except areas associated with schools or other institutions), cemeteries, and entrapped agricultural and undeveloped land within urban areas.
20 Agriculture
21 Cropland - Field crops and forage crops.
22 Pasture - Land used for pasture, both permanent and rotated; grass.
23 Orchards/vineyards/horticulture - Areas of intensively managed commercial bush and tree crops, including areas used for fruit production, vineyards, sod and seed farms, nurseries, and green houses.
24 Feeding operations - Cattle feed lots, holding lots for animals, hog feeding lots, poultry houses, and commercial fishing areas (including oyster beds).
241 Feeding operations - Cattle feed lots, holding lots for animals, hog feeding lots, poultry houses.
242 Agricultural building breeding and training facilities, storage facilities, built-up areas associated with a farmstead, small farm ponds, commercial fishing areas.
25 Row and garden crops - Intensively managed truck and vegetable farms and associated areas.
40 Forest
41 Deciduous forest - Forested areas in which the trees characteristically lose their leaves at the end of the growing season. Included are such species as oak, hickory, aspen, sycamore, birch, yellow poplar, elm, maple, and cypress.
42 Evergreen forest - Forested areas in which the trees are characterized by persistent foliage throughout the year. Included are such species as white pine, pond pine, hemlock, southern white cedar, and red pine.
43 Mixed forest - Forested areas in which neither deciduous nor evergreen species dominate, but in which there is a combination of both types.
44 Brush - Areas which do not produce timber or other wood products but may have cut-over timber stands, abandoned agriculture fields, or pasture. These areas are characterized by vegetation types such as sumac, vines, rose, brambles, and tree seedlings.
50 Water - Rivers, waterways, reservoirs, ponds, bays, estuaries, and ocean.
60 Wetlands - Forested or non-forested wetlands, including tidal flats, tidal and non-tidal marshes, and upland swamps and wet areas.
70 Barren land
71 Beaches - Extensive shoreline areas of sand and gravel accumulation, with no vegetative cover or other land use.
72 Bare exposed rock - Areas of bedrock exposure, scarps, and other natural accumulations of rock without vegetative cover.
73 Bare ground - Areas of exposed ground caused naturally, by construction, or by other cultural processes.
2000 Land Use/Land Cover for Maryland (MDP)
Data generation
Originating Agency: Maryland Department of Planning
Projection and Units: Maryland State Plane Coordinates - meters
Datum: NAD 1983
Initially developed using high altitude aerial photography and satellite imagery. Urban land use categories were further refined using parcel data from MDPropertyView.
Minimum Mapping Unit: 10 acres
Land use classification
The land use/land cover classification scheme described below has been used to identify the predominant usage of land that could be interpreted from high altitude aerial photography and satellite imagery. The LU_CODE field, in each county land use shape file, contains the 2 or 3 digit integer numbers identified below. In general, only land uses greater than 10 acres in size have been identified, although urban land is identified at a smaller scale by comparisons with parcel data from MDPropertyView. Transportation features such as roads, highways, rail lines and utility lines have not been included in this GIS database. Transportation features are better represented by the point and line files available from the Maryland State Highway Administration.
10 Urban Built-Up
11 Low-density residential - Detached single-family/duplex dwelling units, yards and associated areas. Areas of more than 90% single-family/duplex dwelling units, with lot sizes of less than five acres but at least one-half acre (.2 dwelling units/acre to 2 dwelling units/acre).
12 Medium-density residential - Detached single-family/duplex, attached single-unit row housing, yards, and associated areas. Areas of more than 90% single-family/duplex units and attached single-unit row housing, with lot sizes of less than one-half acre but at least one-eighth acre (2 dwelling units/acre to 8 dwelling units/acre).
13 High-density residential - Attached single-unit row housing, garden apartments, high-rise apartments/condominiums, mobile home and trailer parks. Areas of more than 90% high-density residential units, with more than 8 dwelling units per acre.
14 Commercial - Retail and wholesale services. Areas used primarily for the sale of products and services, including associated yards and parking areas.
15 Industrial - Manufacturing and industrial parks, including associated warehouses, storage yards, research laboratories, and parking areas.
16 Institutional - Elementary and secondary schools, middle schools, junior and senior high schools, public and private colleges and universities, military installations (built-up areas only, including buildings and storage, training, and similar areas), churches, medical and health facilities, correctional facilities, and government offices and facilities that are clearly separable from the surrounding land cover.
17 Extractive - Surface mining operations, including sand and gravel pits, quarries, coal surface mines, and deep coal mines. Status of activity (active vs. abandoned) is not distinguished.
18 Open urban land - Urban areas whose use does not require structures, or urban areas where non-conforming uses characterized by open land have become isolated. Included are golf courses, parks, recreation areas (except areas associated with schools or other institutions), cemeteries, and entrapped agricultural and undeveloped land within urban areas.
20 Agriculture
21 Cropland - Field crops and forage crops.
22 Pasture - Land used for pasture, both permanent and rotated; grass.
23 Orchards/vineyards/horticulture - Areas of intensively managed commercial bush and tree crops, including areas used for fruit production, vineyards, sod and seed farms, nurseries, and green houses.
24 Feeding operations - Cattle feed lots, holding lots for animals, hog feeding lots, poultry houses, and commercial fishing areas (including oyster beds).
241 Feeding operations - Cattle feed lots, holding lots for animals, hog feeding lots, poultry houses.
242 Agricultural building breeding and training facilities, storage facilities, built-up areas associated with a farmstead, small farm ponds, commercial fishing areas.
25 Row and garden crops - Intensively managed truck and vegetable farms and associated areas.
40 Forest
41 Deciduous forest - Forested areas in which the trees characteristically lose their leaves at the end of the growing season. Included are such species as oak, hickory, aspen, sycamore, birch, yellow poplar, elm, maple, and cypress.
42 Evergreen forest - Forested areas in which the trees are characterized by persistent foliage throughout the year. Included are such species as white pine, pond pine, hemlock, southern white cedar, and red pine.
43 Mixed forest - Forested areas in which neither deciduous nor evergreen species dominate, but in which there is a combination of both types.
44 Brush - Areas which do not produce timber or other wood products but may have cut-over timber stands, abandoned agriculture fields, or pasture. These areas are characterized by vegetation types such as sumac, vines, rose, brambles, and tree seedlings.
50 Water - Rivers, waterways, reservoirs, ponds, bays, estuaries, and ocean.
60 Wetlands - Forested or non-forested wetlands, including tidal flats, tidal and non-tidal marshes, and upland swamps and wet areas.
70 Barren land
71 Beaches - Extensive shoreline areas of sand and gravel accumulation, with no vegetative cover or other land use.
72 Bare exposed rock - Areas of bedrock exposure, scarps, and other natural accumulations of rock without vegetative cover.
73 Bare ground - Areas of exposed ground caused naturally, by construction, or by other cultural processes.
80 Transportation - Miscellaneous Transportation features not elsewhere classified.
National Land Cover Dataset 1992 (NLCD)
Data generation
Originating Agency: U.S Geological Survey (USGS)
Projection and Units: Albers Conical Equal Area - meters
Datum: NAD 1983
Compiled from Landsat satellite TM imagery with a spatial resolution of 30 m and supplemented by various ancillary data (where available).
Minimum Mapping Unit: 30 m x 30 m
Land use classification
11 Open Water - areas of open water, generally with less than 25% or greater cover of water (per pixel).
12 Perennial Ice/Snow - All areas characterized by year-long cover of ice and/or snow.
Developed - areas characterized by high percentage (»30% or greater) of constructed materials (e.g., asphalt, concrete, buildings, etc).
21 Low Intensity Residential - Includes areas with a mixture of constructed materials and vegetation. Constructed materials account for 30-80% of the cover. Vegetation may account for 20 to 70% of the cover. These areas most commonly include single-family housing units. Population densities will be lower than in high intensity residential areas.
22 High Intensity Residential - Includes heavily built up urban centers where people reside in high numbers. Examples include apartment complexes and row houses. Vegetation accounts for less than 20% of the cover. Constructed materials account for 80-100% of the cover.
23 Commercial/Industrial/Transportation - Includes infrastructure (e.g., roads, railroads, etc.) and all highways and all developed areas not classified as High Intensity Residential.
Barren - Areas characterized by bare rock, gravel, sad, silt, clay, or other earthen material, with little or no "green" vegetation present regardless of its inherent ability to support life. Vegetation, if present, is more widely spaced and scrubby than that in the "green" vegetated categories; lichen cover may be extensive.
31 Bare Rock/Sand/Clay - Perennially barren areas of bedrock, desert, pavement, scarps, talus, slides, volcanic material, glacial debris, and other accumulations of earthen material.
32 Quarries/Strip Mines/Gravel Pits - Areas of extractive mining activities with significant surface expression.
33 Transitional - Areas of sparse vegetative cover (less than 25% that are dynamically changing from one land cover to another, often because of land use activities. Examples include forest clearcuts, a transition phase between forest and agricultural land, the temporary clearing of vegetation, and changes due to natural causes(e.g., fire, flood, etc.)
Forested Upland - Areas characterized by tree cover (natural or seminatural woody vegetation, generally greater than 6 m tall); Tree canopy accounts for 25-100% of the cover.
41 Deciduous Forest - Areas dominated by trees where 75% or more of the tree species shed foliage simultaneously in response to seasonal change.
42 Evergreen Forest - Areas characterized by trees where 75% or more of the tree species maintain their leaves all year. Canopy is never without green foliage.
43 Mixed Forest - Areas dominated by trees where neither deciduous nor evergreen species represent more than 75% of the cover present.
Shrubland - Areas characterized by natural or seminatural woody vegetation with aerial stems, generally less than 6 m tall with individuals or clumps not touching to interlocking. Both evergreen and deciduous species of true shrubs, young trees, and trees or shrubs that are small or stunted because of environmental conditions are included.
51 Shrubland - Areas dominated by shrubs; shrub canopy accounts for 25-100% of the cover. Shrub cover is generally greater than 25% when tree cover is less than 25%. Shrub cover may be less than 25% in cases when the cover of other life forms (e.g., herbaceous or tree) is less than 25% and shrubs cover exceeds the cover of the other life forms.
Non-natural Woody - Areas dominated by non-natural woody vegetation; non-natural woody vegetative canopy accounts for 25-100% of the cover. The non-natural woody classification is subject to the availability of sufficient ancillary data to differentiate non-natural woody vegetation from natural woody vegetation.
61 Orchards/Vineyards/Other - Orchards, vineyards, and other areas planted or maintained for the production of fruits, nuts, berries, or ornamentals.
Herbaceous Upland - Upland areas characterized by natural or semi- natural herbaceous vegetation; herbaceous vegetation accounts for 75-100% of the cover.
71 Grasslands/Herbaceous - Areas dominated by upland grasses and forbs. In rare cases, herbaceous cover is less than 25%, but exceeds the combined cover of the woody species present. These areas are not subject to intensive management, but they are often used for grazing.
Planted/Cultivated - Areas characterized by herbaceous vegetation that have been planted or is intensively managed for the production of food, feed, or fiber; or is maintained in developed settings for specific purposes. Herbaceous vegetation accounts for 75-100% of the cover.
81 Pasture/Hay - Areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the production of seed or hay crops.
82 Row Crops - Areas used for the production of crops, such as corn, soybeans, vegetables, tobacco, and cotton.
83 Small Grains - Areas used for the production of graminoid crops such as wheat, barley, oats, and rice
84 Fallow - Areas used for the production of crops that are temporarily barren or with sparse vegetative cover as a result of being tilled in a management practice that incorporates prescribed alternation between cropping and tillage.
85 Urban/Recreational Grasses - Vegetation (primarily grasses) planted in developed settings for recreation, erosion control, or aesthetic purposes. Examples include parks, lawns, golf courses, airport grasses, and industrial site grasses.
Wetlands - Areas where the soil or substrate is periodically saturated with or covered with water as defined by Cowardin et al.
91 Woody Wetlands - Areas where forest or shrubland vegetation accounts for 25-100% of the cover and the soil or substrate is periodically saturated with or covered with water.
92 Emergent Herbaceous Wetlands - Areas where perennial herbaceous vegetation accounts for 75-100% of the cover and the soil or substrate is periodically saturated with or covered with water.
National Land Cover Dataset 2001 (NLCD)
Data generation
Originating Agency: U.S Geological Survey (USGS)
Projection and Units: Albers Conical Equal Area - meters
Datum: NAD 1983
Compiled from Landsat satellite TM imagery with a spatial resolution of 30 m and supplemented by various ancillary data (where available).
Minimum Mapping Unit: 30 m x 30 m
Land use classification
11 Open Water - All areas of open water, generally with less than 25% cover of vegetation or soil.
12 Perennial Ice/Snow - All areas characterized by a perennial cover of ice and/or snow, generally greater than 25% of total cover.
21 Developed, Open Space - Includes areas with a mixture of some constructed materials, but mostly vegetation in the form of lawn grasses. Impervious surfaces account for less than 20% of total cover. These areas most commonly include large-lot single-family housing units, parks, golf courses, and vegetation planted in developed settings for recreation, erosion control, or aesthetic purposes
22 Developed, Low Intensity - Includes areas with a mixture of constructed materials and vegetation. Impervious surfaces account for 20-49% of total cover. These areas most commonly include single-family housing units.
23 Developed, Medium Intensity - Includes areas with a mixture of constructed materials and vegetation. Impervious surfaces account for 50-79% of the total cover. These areas most commonly include single-family housing units.
24 Developed, High Intensity - Includes highly developed areas where people reside or work in high numbers. Examples include apartment complexes, row houses and commercial/industrial. Impervious surfaces account for 80 to100% of the total cover.
31 Barren Land (Rock/Sand/Clay) - Barren areas of bedrock, desert pavement, scarps, talus, slides, volcanic material, glacial debris, sand dunes, strip mines, gravel pits and other accumulations of earthen material. Generally, vegetation accounts for less than 15% of total cover.
32 Unconsolidated Shore* - Unconsolidated material such as silt, sand, or gravel that is subject to inundation and redistribution due to the action of water. Characterized by substrates lacking vegetation except for pioneering plants that become established during brief periods when growing conditions are favorable. Erosion and deposition by waves and currents produce a number of landforms representing this class.
41 Deciduous Forest - Areas dominated by trees generally greater than 5 m tall, and greater than 20% of total vegetation cover. More than 75% of the tree species shed foliage simultaneously in response to seasonal change.
42 Evergreen Forest - Areas dominated by trees generally greater than 5 m tall, and greater than 20% of total vegetation cover. More than 75% of the tree species maintain their leaves all year. Canopy is never without green foliage.
43 Mixed Forest - Areas dominated by trees generally greater than 5 m tall, and greater than 20% of total vegetation cover. Neither deciduous nor evergreen species are greater than 75% of total tree cover.
51 Dwarf Scrub - Alaska only areas dominated by shrubs less than 20 centimeters tall with shrub canopy typically greater than 20% of total vegetation. This type is often co-associated with grasses, sedges, herbs, and non-vascular vegetation.
52 Shrub/Scrub - Areas dominated by shrubs; less than 5 m tall with shrub canopy typically greater than 20% of total vegetation. This class includes true shrubs, young trees in an early successional stage or trees stunted from environmental conditions.
71 Grassland/Herbaceous - Areas dominated by grammanoid or herbaceous vegetation, generally greater than 80% of total vegetation. These areas are not subject to intensive management such as tilling, but can be used for grazing.
72 Sedge/Herbaceous - Alaska only areas dominated by sedges and forbs, generally greater than 80% of total vegetation. This type can occur with significant other grasses or other grass like plants, and includes sedge tundra, and sedge tussock tundra.
73 Lichens - Alaska only areas dominated by fruticose or foliose lichens generally greater than 80% of total vegetation.
74 Moss - Alaska only areas dominated by mosses, generally greater than 80% of total vegetation.
81 Pasture/Hay - Areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or the production of seed or hay crops, typically on a perennial cycle. Pasture/hay vegetation accounts for greater than 20% of total vegetation.
82 Cultivated Crops - Areas used for the production of annual crops, such as corn, soybeans, vegetables, tobacco, and cotton, and also perennial woody crops such as orchards and vineyards. Crop vegetation accounts for greater than 20% of total vegetation. This class also includes all land being actively tilled.
90 Woody Wetlands - Areas where forest or shrubland vegetation accounts for greater than 20% of vegetative cover and the soil or substrate is periodically saturated with or covered with water.
91 Palustrine Forested Wetland* -Includes all tidal and non-tidal wetlands dominated by woody vegetation greater than or equal to 5 m in height and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is below 0.5%. Total vegetation coverage is greater than 20%.
92 Palustrine Scrub/Shrub Wetland* - Includes all tidal and non-tidal wetlands dominated by woody vegetation less than 5 m in height, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is below 0.5%. Total vegetation coverage is greater than 20%. The species present could be true shrubs, young trees and shrubs or trees that are small or stunted due to environmental conditions.
93 Estuarine Forested Wetland* - Includes all tidal wetlands dominated by woody vegetation greater than or equal to 5 m in height, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is equal to or greater than 0.5%. Total vegetation coverage is greater than 20%.
94 Estuarine Scrub/Shrub Wetland* - Includes all tidal wetlands dominated by woody vegetation less than 5 m in height, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is equal to or greater than 0.5%. Total vegetation coverage is greater than 20%.
95 Emergent Herbaceous Wetlands - Areas where perennial herbaceous vegetation accounts for greater than 80% of vegetative cover and the soil or substrate is periodically saturated with or covered with water.
96 Palustrine Emergent Wetland (Persistent)* - Includes all tidal and non-tidal wetlands dominated by persistent emergent vascular plants, emergent mosses or lichens, and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is below 0.5%. Plants generally remain standing until the next growing season.
97 Estuarine Emergent Wetland* - Includes all tidal wetlands dominated by erect, rooted, herbaceous hydrophytes (excluding mosses and lichens) and all such wetlands that occur in tidal areas in which salinity due to ocean-derived salts is equal to or greater than 0.5% and that are present for most of the growing season in most years. Perennial plants usually dominate these wetlands.
98 Palustrine Aquatic Bed* - The Palustrine Aquatic Bed class includes tidal and nontidal wetlands and deepwater habitats in which salinity due to ocean-derived salts is below 0.5% and which are dominated by plants that grow and form a continuous cover principally on or at the surface of the water. These include algal mats, detached floating mats, and rooted vascular plant assemblages.
99 Estuarine Aquatic Bed* - Includes tidal wetlands and deepwater habitats in which salinity due to ocean-derived salts is equal to or greater than 0.5% and which are dominated by plants that grow and form a continuous cover principally on or at the surface of the water. These include algal mats, kelp beds, and rooted vascular plant assemblages.
* Coastal NLCD class only