Section 1: Introduction The changing landscape of Canadian metropolitan areas
Section 1: Introduction

The following analyses make use of two main geographic units—the census metropolitan area (CMA) (Map 1.1) and the 'census metropolitan area-ecosystem' (CMA-E), a unit created for this report. For further information about data sets and methods see Appendix B. Data sources and methods.

What is a census metropolitan area (CMA)?

A census metropolitan area (CMA) is formed by one or more adjacent municipalities centred on a population centre (known as the core). A CMA must have a total population of at least 100,000 of which 50,000 or more must live in the core. To be included in the CMA other adjacent municipalities must have a high degree of integration with the core, as measured by commuting flows derived from previous census place of work data. Once an area becomes a CMA, it is retained as a CMA even if its total population declines below 100,000 or the population of its core falls below 50,000.^{Note 1}

What is a census metropolitan area-ecosystem (CMA-E)?

The census metropolitan area-ecosystem (CMA-E) is a spatial unit that combines CMAs with an environmental geography—the Soil Landscapes of Canada (SLC).^{Note 2} The CMA-E combines any SLC polygon that is contained within or that intersects the CMA boundary, as well as SLC polygons that are fully contained within this newly formed boundary of the CMA-E.

SLC polygons delineate the major permanent natural attributes of soil and land. These attributes include soil type, surface form, slope, surface water and water table depth, and therefore provide information on some basic ecosystem characteristics. SLC polygons are the smallest element of the National Ecological Framework for Canada.^{Note 3} The SLC polygons included in CMA-Es vary in size from 7 km² to over 17,000 km².

The CMA-E unit is not meant to delineate ecosystems as such, but instead was developed to help explore CMAs from an ecosystem perspective. It recognizes that cities, with their politically and administratively defined boundaries, depend on natural surroundings to provide ecosystem goods and services, as well as the physical space for urban expansion. Use of this unit allows for the development of a fuller picture of land use change and urban expansion around CMAs since urban expansion often depends on environmental assets including land located outside city boundaries. As well, the Census of Agriculture data used in this report are available by SLC polygons and provide insight on relationships between the environment and the economy.^{Note 4}

CMA-Es are not spatially mutually exclusive—they overlap where a SLC polygon crosses more than one CMA boundary, as is the case in Vancouver and Abbotsford–Mission or Toronto and surrounding CMAs including Hamilton, Oshawa, Kitchener–Cambridge–Waterloo, Guelph, Brantford and Barrie. For this reason, land use or population data for CMA-Es should not be summed to generate a total and caution should be used when comparing data. See maps in Section 3: Ecosystem accounts and statistics by census metropolitan area for a visual representation of the CMA-E boundaries.

Principal data sources

This study combines data from the 1971, 1991, 2001 and 2011 Census of Population^{Note 5} and Interpolated Census of Agriculture^{Note 6} with spatial data sets providing information on land cover and land use, in order to analyze the evolution of built-up areas around CMAs.

The Canada Land Inventory: Land Use (circa 1966) (CLI: LU),^{Note 7} supplemented with the Canada Land Inventory Monitoring Program (CLUMP): Land Use 1971,^{Note 8} were used to estimate the 1971 built-up area. CLUMP coverage excludes the CMAs of Moncton, Trois-Rivières, Sherbrooke, Peterborough, Kingston, Barrie, Brantford, Kelowna and Abbotsford–Mission.

Canada Land Inventory: Soil Capability for Agriculture, 1969^{Note 9} provides information on the potential of a specific area for agricultural production. Despite the vintage of this product and the availability of more recent soil data for some areas, the soil capability interpretations are considered to be largely valid and they continue to be used for land planning purposes.^{Note 10}

Remote sensing imagery data are taken from Agriculture and Agri-Food Canada's Land Use 1990, 2000 and 2010.^{Note 11} These land use maps cover all of Canada south of 60°N at a spatial resolution of 30 m and were developed to meet international reporting requirements including for the National Inventory Report to the United Nations Framework Convention on Climate Change, the Agri-Environmental program of the Organisation for Economic Co-operation and Development (OECD) and the FAOSTAT component of the Food and Agricultural Organization of the United Nations (FAO).

Each data set is subject to limitations. In particular, the accuracy of land cover classification using spatial data sets depends on the resolution of the data and imagery dates and is also limited by the similarity of certain land covers when viewed from above and by cloud and tree canopy cover, which can obscure underlying land features.

This report uses a consistent methodology to compare urban development trends across the country, allowing inter-city comparison. However, it is recognized that this broad scale analysis does not capture the finer details that are required to assess all the environmental impacts of the development of cities.

For more information about sources and methods used here see Appendix B.

Land is a distinct category of natural capital. This environmental asset is at the foundation of ecosystem services and economic activities, providing the space for these to occur. When measuring the extent, condition or quality of this asset, it is useful to distinguish between two land characteristics—land cover and land use.

Land cover refers to the observed physical and biological surface of the Earth and includes biotic (living, such as vegetation) and abiotic (non-living, such as rocks) surfaces. Built-up areas are human-produced and include both abiotic and biotic components, for example impervious surfaces like roads and buildings, as well as gardens, backyards, parks and playing fields. Land cover can be determined by field assessment and using aerial photography and satellite imagery.

Land use, on the other hand, describes the economic and social functions of land to meet human demands, including activities and institutional arrangements to maintain or restore natural habitats. Typical land use classes include agriculture, settled areas and managed areas.^{Note 12}

The two concepts—land cover and land use—are intertwined since some land uses depend on the type of land cover and land use also affects and changes land cover. This report presents data for both types of classifications—for example, forests, which reflects land cover, and arable land, which reflects land use.