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GEO-6 Regional Assessment for North America


still positive, rate of forest-to-cropland change. In absolute terms rather than percentages, from 1993 to 2013, 405 000 hectares of Canadian forest were converted to cropland use. This is down from the 1 286 000 ha of forest converted to cropland from 1970 to 1990.


Farmland conversion has been more common in eastern Canada.


Since 1993, 83 per cent of forest-to-cropland


conversions occurred in eastern Canada and only 10 per cent in the Prairie Provinces. The cropland-to-forest changes are largely occurring on privately-owned lots where marginal cropland is being taken out of production and planted with trees. This transition has primarily affected croplands where production was abandoned some years ago (e.g., old Christmas tree plantations, vineyards and old fields that naturally transitioned to woody species), and that in the most recent forest inventory finally had enough woody species to meet the definition of forest. The area of marginal cropland left to naturally transition to forest has not been quantified either by the current national forest inventory programme or the Census of Agriculture. Marginal agricultural land remains classified as cropland until sufficient tree cover emerges to meet the forest definition.


Unfortunately, inventories and monitoring programmes relied on for estimating land-use changes for greenhouse gas reporting, do not currently estimate the amount of cropland converted to settlements. However, other reports have documented significant changes. Canada’s agricultural land is classified based on its quality and constraints for production. The top three classes are called ‘dependable agricultural land’ (DAL) and total 49.3 million hectares. DAL is valuable because it has no severe constraints on production and because it is scarce;accounting for only 5 per cent of all agriculture land. Hofmann (2001) found that from 1971 to 1996, urban areas had consumed 1.2 million hectares of land; half of that being DAL. By 1996, urban areas covered 2.8 million hectares across Canada and 52 per cent of the urban area was on DAL. Hofmann et al. (2005) reported further loss of DAL to development, reporting that in 2001, urban areas occupied 3 per cent of all DAL; more importantly, 7.5 per cent of Class 1 DAL. When urban and rural built-up areas are combined with transportation and utility corridors and


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other developed land, 4 million acres of DAL—8.1 per cent of the nation’s endowment—was in non-agricultural land- use. A corroborating analysis by Statistics Canada (2014) found that settlements on DAL increased by 19 per cent from 2000 to 2011. By ecozone, the largest increase of urban intrusion onto dependable agricultural land occurred in the Mixed Wood Plains, where the settled area on dependable agricultural land grew by 128 030 hectares (+27 per cent)— over half this growth came from the Greater Golden Horseshoe region. The second largest increase was noted in the Prairies ecozone, where settled area on dependable agricultural land increased 59 807 hectares (+16 per cent ). As Canada’s population grows and cities develop and spread outward, the loss of some of the country’s best farmland will likely continue, given that many population centers are located near some of the best farmland in the country.


Conversion of other land-uses to settlement also continues. In the four years from 2010 to 2014, settlements added 499 600 hectares; the vast majority (498 790 hectares) from forest land-use (Government of Canada 2014). A small amount of grassland (820 ha)—mostly tundra in far northern regions— also was converted to settlements. While that conversion of forest to settlement use was tiny (0.13 per cent), it demonstrates that forest areas surrounding settlements are a target for urban expansion across the country.


2.2.2 US land-use change


Forests account for 30 per cent of the US land area; grazing and pasturelands, 27 per cent; cropland, 18 per cent; and urban areas, 3 per cent. The proportions vary widely by region.


The Great Plains and Rocky Mountain regions


together have more than three-quarters of the nation’s grazing land and a third of the cropland. The northern states have the largest percentage of land in forests (41 per cent) and 35 per cent of the nation’s cropland, while the southern states have the largest percentage of the nation’s timberland (40 per cent). Population is heavily concentrated in urban areas. The West has 90 per cent of its population in urban areas, the northeast has 85 per cent, and the Midwest and the South each have 76 per cent (US Census Bureau 2012).


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