Ontario Land Cover - National-Scale (1:250,000) Version

The Ontario Land Cover data base was produced by the Ontario Ministry of Natural Resources from satellite remote sensing image data. The land cover mapping classification was derived from digital, multispectral LANDSAT Thematic Mapper image data recorded on a range of dates between 1986 and 1997, the majority in the early 1990s. The forest cutovers and burns were updated from 1996 Thematic Mapper coverage for the Great Lakes forest region and most of the Boreal forest region of Ontario. As the name implies, the National-Scale Ontario Land Cover data base is a generalization of the above data to a national scale, both in terms of the spatial resolution and the number of classes. The original data, containing 28 land cover classes with a minimum area of 0.6 hectare and a pixel size of 25 metres, is distributed by the Ontario Ministry of Natural Resources. The National-Scale Ontario Land Cover data base available through GeoGratis contains 15 land cover classes, a feature minimum area of 50 hectares, and a pixel size of 100 metres. These data are distributed on the basis of 1:250,000-scale map sheets of the National Topographic Series. The land cover classes consist of vegetation types (such as forest, wetlands, and agricultural crops or pasture) and categories of non-vegetated surface (such as water bodies, bedrock outcrops, or settlements). Unlike the land use classes of the historical Canada Land Inventory, the Ontario Land Cover classification reflects the nature of the land surface rather than the land use. For example, provincial parks are not discriminated as areas of recreational land use, but are mapped as part of the provincial mosaic of water bodies, forest types, wetlands, and other cover classes. Satellite land cover classification identifies cover types by their spectral character; that is, by the nature of the various wavelengths of the sun's energy reflected from them. This spectral character is determined by the vegetation cover and other types of surface that make up each land cover type. For example, forest types are identified by the mixture of coniferous and deciduous species, the degree of canopy closure, and the ground cover visible through canopy gaps. Similary, wetland types are identified by the nature of the vegetation cover (trees, grasses, or mosses) and the proportion of open water. Agricultural land cover is distinguished by the spectral character of growing row crops, pasture, or open soil. Forest cutovers are recognized by a combination of spectral reflectance, internal pattern, and context. The land cover classification was performed using a type of computer analysis identified as a "supervised" classification method. ("Supervised" indicates that the image interpreter first assigned meaning to differences found across a satellite image frame, then sought out all other occurrences of the same features. An "unsupervised" classification method involves classifying all of the discernible differences across the image frame, then assigning a meaning to those differences.) Use of the supervised classification approach requires prior knowledge of the range of land cover conditions in the area under study. Extensive field knowledge was brought to bear on the Ontario land cover classification process. Interactive editing was used extensively to map certain classes that could not be positively identified without taking pattern and/or context into account, in addition to spectral values. The knowledgeable use of editing techniques significantly improved the overall accuracy of the land cover data. _ NATIONAL-SCALE ONTARIO LAND COVER CLASSES PREPARED FOR GEOGRATIS DATA DISTRIBUTION 1. Water 2. Marshes 3. Open Wetlands 4. Treed Wetlands 5. Tundra Heath 6. Dense Deciduous Forest 7. Dense Coniferous Forest 8. Mixed Forest 9. Sparse Forest 10. Early Successional Forest 11. Successional Forest 12. Mine Tailings, Quarries, Bedrock Outcrop, Mudflats 13. Settlement and Developed Land 14. Agriculture 15. Unclassified Areas (within the province) Purpose: The lower-resolution, 15-class, National-Scale Ontario Land Cover data set provides the basis for calculating the representation of general land cover types in Ontario. It also provides a valuable land cover layer for a wide range of GIS applications. By representing land cover conditions to the early 1990s, for the most part, and successional forest classes to 1996, the data set provides a historical baseline for future land cover monitoring. The higher-resolution, 28-class, Ontario Provincial-Scale Land Cover data set provides the basis for calculations of selected or combined forest types, wetlands, or agricultural land cover. These and other analyses provide information for resource management planning within a user-defined management zone (e.g., a management district or region, a conservation area, a county, or a watershed). The data have also been used to generate provincial and regional forest landscape ecological analyses. In combination with land cover from other sources (for example, either historical or future satellite data coverage), the data set provides for detecting change in land cover and, by inference, in land use.