Higher densities and areas of trees, with largely closed canopy, provide extensive and nearly continuous shade are referred to as forest. Savanna Savanna is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses. Desert Desert is a landscape or region that receives an extremely low amount of precipitation, defined as areas with an average annual precipitation of less than per year, or as areas where more water is lost by evapotranspiration than falls as precipitation. In the Köppen climate classification system, deserts are classed as BWh (hot desert) or BWk (temperate desert). In the Thornthwaite climate classification system, deserts would be classified as arid megathermal climates. Tundra Tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." There are three types of tundra: Arctic tundra, alpine tundra, and Antarctic tundra In tundra, the vegetation is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered trees grow in some tundra. The ecotone (or ecological boundary region) between the tundra and the forest is known as the tree line or timberline. North America Canada Rangeland is a prominent feature of rural Canada. A provincial jurisdiction, administration and policy regarding range use varies across the country. As in many other Commonwealth countries, public tenures on crown land for the purpose of range activities are common in geographically compatible areas. Reconciling the economic needs of ranchers and the need for environmental conservation is one of the primary themes in modern range discourse. In western Canada, both grassland and forested range are significant. In British Columbia, 70 percent of grassland range is privately owned and 60 percent of the total annual livestock forage requirement is provided by grazing on Crown rangeland (34 million hectares), 80 percent of which is forested range. Grassland range predominates in much of the prairie provinces’ ranching area; however, forested range is particularly important in the boreal region. Certain rangelands are preserved as provincially-protected areas similar to parks, others are managed as community resources. For example, in Alberta since 2003 there has been legislation allowing the creation of "Heritage Rangelands" within the parks