39 résultats pour "grasslands"

• Dry Grasslands - geography.

• Saskatchewan (province) - Geography.

  The length of the frost-free season varies within the province. In the southwest, particularly in the valley lands along the South Saskatchewan River, the frost-freeperiod ranges from 150 to 160 days. Regina enjoys about 123 frost-free days, and Saskatoon has about 111. The far north has only from 85 to 95 frost-free days. One important characteristic of Saskatchewan’s climate is the great variability in temperature and precipitation from year to year, which is often critical for agriculture.The...

• Saskatchewan (province) - Canadian History.

  The length of the frost-free season varies within the province. In the southwest, particularly in the valley lands along the South Saskatchewan River, the frost-freeperiod ranges from 150 to 160 days. Regina enjoys about 123 frost-free days, and Saskatoon has about 111. The far north has only from 85 to 95 frost-free days. One important characteristic of Saskatchewan’s climate is the great variability in temperature and precipitation from year to year, which is often critical for agriculture.The...

• China - country.

  North China lies between the Mongolian Steppe on the north and the Yangtze River Basin on the south. It stretches west from the Bo Hai gulf and the Yellow Sea to theeastern edge of the Tibetan Plateau. Administratively, North China includes Beijing and Tianjin municipalities; Shandong and Shanxi provinces; most of Hebei, Henan,and Shaanxi provinces; and portions of Ningxia Hui Autonomous Region and of Jiangsu, Anhui, and Gansu provinces. Humans have lived in the agriculturally rich region of Nor...

• North Dakota - geography.

  Bismarck, the growing season averages 134 days, as the average date of the last killing frost is May 11 and that of the first killing frost is September 22. The length ofthe growing season drops to about 110 days in the northerly reaches of the state. The long periods of summer sunshine at this latitude, providing as much as 16 hoursof daylight in summer, help crops to mature quickly, thus compensating somewhat for the relatively short growing season. Temperatures in the north are, on the averag...

• North Dakota - USA History.

  Bismarck, the growing season averages 134 days, as the average date of the last killing frost is May 11 and that of the first killing frost is September 22. The length ofthe growing season drops to about 110 days in the northerly reaches of the state. The long periods of summer sunshine at this latitude, providing as much as 16 hoursof daylight in summer, help crops to mature quickly, thus compensating somewhat for the relatively short growing season. Temperatures in the north are, on the averag...

• Nebraska - geography.

  by natural resource districts to limit the rate of pumping for irrigation. C Climate Nebraska has a typical continental climate with wide seasonal variations in temperature. C1 Temperature Winter temperatures below -20°C (0° F) and summer temperatures in the upper 30°s C (lower 100°s F) are common. The average January temperature varies from about -7° C (about 20° F) in the northeast to about -2° C (about 29° F) in the southwest. The average for July, thehottest month, ranges from about 26° C...

• Nebraska - USA History.

  by natural resource districts to limit the rate of pumping for irrigation. C Climate Nebraska has a typical continental climate with wide seasonal variations in temperature. C1 Temperature Winter temperatures below -20°C (0° F) and summer temperatures in the upper 30°s C (lower 100°s F) are common. The average January temperature varies from about -7° C (about 20° F) in the northeast to about -2° C (about 29° F) in the southwest. The average for July, thehottest month, ranges from about 26° C...

• South Africa - country.

  The major soil zones are conditioned largely by climatic factors. In the semiarid north and west, soils are alkaline and poorly developed. In the southern part of WesternCape Province, rain falls mostly in the winter months, and soils there form slowly and are generally thin and immature. The moderate temperatures and summer rainfallof the High Veld and eastern coastal areas create conditions for more productive organic decomposition, leading to dark, fertile soils, or chernozems, similar to tho...

• Arizona - geography.

  of the Mogollon Rim, the Little Colorado draws very little water from a relatively large watershed, usually containing a mere trickle of water in its riverbed. The ColoradoRiver’s principal tributary is the Gila River, which flows all the way across the southern part of the state from New Mexico to the California border. From the mountainsand plateaus of central Arizona, the Gila River receives the Salt, Agua Fria, and Hassayampa rivers. The Salt River is itself fed by the Verde River. The Gila...

• Arizona - USA History.

  of the Mogollon Rim, the Little Colorado draws very little water from a relatively large watershed, usually containing a mere trickle of water in its riverbed. The ColoradoRiver’s principal tributary is the Gila River, which flows all the way across the southern part of the state from New Mexico to the California border. From the mountainsand plateaus of central Arizona, the Gila River receives the Salt, Agua Fria, and Hassayampa rivers. The Salt River is itself fed by the Verde River. The Gila...

• Mammal - biology.

  On land, mammals live in many different habitats, and at a wide range of altitudes. Many mammals dig burrows as refuges or as places to raise their young, but somehave developed a largely subterranean lifestyle, feeding on small animals or plant roots beneath the soil's surface. These animals, including moles and mole-rats, digthrough the ground either with spadelike front paws or with their teeth, and they detect danger by being highly sensitive to vibrations transmitted through the soil.Most m...

• Wyoming (state) - geography.

  The basins, which lie in the rain shadow of mountains, are very dry, with an average annual precipitation of about 250 mm (about 10 in) or less; the Great Plains regionhas an annual average of about 380 mm (about 15 in), and the Black Hills region receives slightly more. Thunderstorms and hailstorms are relatively frequent insummer. The annual snowfall ranges from about 500 mm (about 20 in) in the Bighorn Basin to well over 5,100 mm (over 200 in) in the higher mountains, where annualprecipitatio...

• Wyoming (state) - USA History.

  The basins, which lie in the rain shadow of mountains, are very dry, with an average annual precipitation of about 250 mm (about 10 in) or less; the Great Plains regionhas an annual average of about 380 mm (about 15 in), and the Black Hills region receives slightly more. Thunderstorms and hailstorms are relatively frequent insummer. The annual snowfall ranges from about 500 mm (about 20 in) in the Bighorn Basin to well over 5,100 mm (over 200 in) in the higher mountains, where annualprecipitatio...

• Illinois - geography.

  the state before joining the Mississippi River at Grafton. The Illinois has been deepened and straightened and forms part of the Illinois Waterway. The watershed between rivers that flow into the Mississippi river system and rivers that flow into the Great Lakes is low and in many places is not easily discernible. Inwhat is now the Chicago area, explorers had little difficulty portaging, or carrying, their canoes over the low watershed between the Des Plaines River, which flows intothe Illinois,...

• Illinois - USA History.

  the state before joining the Mississippi River at Grafton. The Illinois has been deepened and straightened and forms part of the Illinois Waterway. The watershed between rivers that flow into the Mississippi river system and rivers that flow into the Great Lakes is low and in many places is not easily discernible. Inwhat is now the Chicago area, explorers had little difficulty portaging, or carrying, their canoes over the low watershed between the Des Plaines River, which flows intothe Illinois,...

• Colorado - geography.

  Although the rivers of Colorado are navigable only by small boats, they are important as a source of irrigation water for use in Colorado and adjoining states. However,the water level of the rivers fluctuates seasonally and from year to year. The level is generally low in winter and high in spring and summer, during the runoff of meltedsnow from the mountains. Colorado has no large lakes of natural origin, but there are numerous small lakes in the mountains. The largest bodies of water in Colora...

• Colorado - USA History.

  Although the rivers of Colorado are navigable only by small boats, they are important as a source of irrigation water for use in Colorado and adjoining states. However,the water level of the rivers fluctuates seasonally and from year to year. The level is generally low in winter and high in spring and summer, during the runoff of meltedsnow from the mountains. Colorado has no large lakes of natural origin, but there are numerous small lakes in the mountains. The largest bodies of water in Colora...

• Texas - geography.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• Texas - USA History.

  D Climate Eastern Texas has a humid subtropical climate, while a semiarid low latitude climate prevails in central areas, and an arid low latitude climate in the extreme west. Alongthe coast the climate is much milder, with fewer extremes in temperatures. Hurricanes sometimes hit the coastal areas of Texas from late July through September, andtornadoes are common in north-central Texas in April and May. D1 Temperature Summers are hot throughout the state, and temperatures exceeding 35°C (95°F)...

• National Parks and Preserves.

  Some ibex raised in Italy’s 700 sq km (220 sq mi) Gran Paradiso National Park (1922) were transferred to aid herd restoration elsewhere in the country. Switzerlandreturned lynx to Swiss National Park to keep red deer populations in check. The growth of national parks also enabled many European countries to restore forests thathad given way to industrialization by the early 20th century. Africa’s wildlife was hunted heavily from the late 19th century well into the 20th century. By 1920 big-game h...

• New Mexico - geography.

  New Mexico’s major river is the Río Grande, originating in southern Colorado, and flowing southward for 760 km (470 mi) through the state. Between the San LuisValley and Española Valley the river flows in a deep canyon known as the Río Grande Gorge; then, below White Rock Canyon, it flows through several valleys containingagricultural land. Most of the water of the Río Grande is used to irrigate these valleys. The Río Grande’s waterflow in New Mexico is extremely low. One of the major tributarie...

• New Mexico - USA History.

  New Mexico’s major river is the Río Grande, originating in southern Colorado, and flowing southward for 760 km (470 mi) through the state. Between the San LuisValley and Española Valley the river flows in a deep canyon known as the Río Grande Gorge; then, below White Rock Canyon, it flows through several valleys containingagricultural land. Most of the water of the Río Grande is used to irrigate these valleys. The Río Grande’s waterflow in New Mexico is extremely low. One of the major tributarie...

• Biodiversity.

  a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...

• Biodiversity - biology.

  a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...

• Venezuela - country.

  Venezuela has six navigable rivers. Of the thousand or more streams in the country, the majority flow into the Orinoco. The Orinoco flows east across central Venezuelaand drains approximately four-fifths of the total area of the country. With the tributaries—the Apure, Meta, and Negro rivers—it forms the outlet into the Atlantic Oceanfor the waters of much of the interior of Colombia, as well as of inland Venezuela. F Climate The climate of Venezuela is tropical on the Llanos and along the coas...

• Oklahoma - geography.

  portion and the Panhandle are classified as a steppe, where precipitation, typically 250 to 500 mm (10 to 20 in), is the controlling characteristic. January is usually the coldest month with an average of about 3°C (38°F) and extremes from -33°C (-27°F), the lowest ever recorded, to 33°C (92°F). Summer arelong and hot with temperatures in the upper 30°s C (lower 100°s F) common from May until September across the state. The growing season varies from less than 180days in the western Panhandle to...

• Oklahoma - USA History.

  portion and the Panhandle are classified as a steppe, where precipitation, typically 250 to 500 mm (10 to 20 in), is the controlling characteristic. January is usually the coldest month with an average of about 3°C (38°F) and extremes from -33°C (-27°F), the lowest ever recorded, to 33°C (92°F). Summer arelong and hot with temperatures in the upper 30°s C (lower 100°s F) common from May until September across the state. The growing season varies from less than 180days in the western Panhandle to...

• Kangaroo - biology.

  ungulates, they have evolved multi-chambered stomachs containing bacteria that can break down plant cell walls and release the nutritious cell contents. V SOCIAL ORGANIZATION Kangaroo social life is poorly understood, as few species have been studied in detail. Small species, such as potoroos, bettongs, and musky rat-kangaroos, tend to besolitary and widely dispersed, with a male's territory encompassing those of several females. The animals come together briefly for mating, and mother and offs...

• South America - geography.

  B Natural Regions Tierra del Fuego, ArgentinaUshuaia, on Argentina’s island of Tierra del Fuego, is the world’s southernmost city. Argentina claims part of the Tierra del Fuegoarchipelago, including the largest island, known as Tierra del Fuego or Great Island, and Staten Island. Chile claims the remainder ofthe islands in the territory.R. Van Nostrand/Photo Researchers, Inc. Rising abruptly from the northwestern and western coasts of the continent are the Andes. They consist of a single chain...

• Biome.

• Benin - country.

  French is the official language of Benin, but most people speak an African language. Each of the country’s ethnic groups has its own language. Fon is the most widelyspoken language. About 52 percent of the population professes traditional religious beliefs, chiefly Vodun, a belief in spirits. Arab merchants introduced Islam to the region, and today it isthe religion of some 20 percent of the people, most of whom live in the north. Christianity, especially Roman Catholicism, is the religion of ab...

• Ecology.

  an input of nutrients exceeding the capability of the ecosystem to process them. Nutrients eroded and leached from agricultural lands, along with sewage and industrialwastes accumulated from urban areas, all drain into streams, rivers, lakes, and estuaries. These pollutants destroy plants and animals that cannot tolerate theirpresence or the changed environmental conditions caused by them; at the same time they favor a few organisms more tolerant to changed conditions. Thus,precipitation filled...

• Ecology - biology.

  an input of nutrients exceeding the capability of the ecosystem to process them. Nutrients eroded and leached from agricultural lands, along with sewage and industrialwastes accumulated from urban areas, all drain into streams, rivers, lakes, and estuaries. These pollutants destroy plants and animals that cannot tolerate theirpresence or the changed environmental conditions caused by them; at the same time they favor a few organisms more tolerant to changed conditions. Thus,precipitation filled...

• Horse - biology.

  Horses reach sexual maturity at about one and a half years. The estrous cycle in the mare—a mature female horse—typically lasts 21 days. During the first five days ofthe cycle, the mare is usually receptive to mating. The estrous cycle stops during winter and resumes in the spring, which is the start of the breeding season. Astallion—a mature male horse—approaching a mare in estrus engages in various courtship rituals. These include uttering nickering sounds and sniffing and licking themare’s ge...

• Birding - biology.

  swallows, and rock doves nest on buildings in cities, towns, and farms. The chimney swift has abandoned hollow trees for chimneys as a nest site in urban areas.Mallards and Canada geese—once exclusively wild, migratory species—now live year-round in the open spaces found in city parks and golf courses. Nearly all purplemartins, a songbird species that once used the abandoned nests of woodpeckers or the natural cavities of cliffs or dead trees, now live primarily in structures specificallyconstru...

• Turkey - country.

  has a general elevation of 900 to 1,500 m (3,000 to 5,000 ft) above sea level. The eastern highlands region is the most mountainous and rugged portion of Turkey; Mount Ararat (Ağrı Da ğı) is the highest peak in the country at 5,165 m (16,945ft). Many Christians and Jews believe it to be the same Mount Ararat mentioned in the Bible as the place where Noah’s ark came to rest. The eastern highlands are thesource for both the Tigris (Dicle) and Euphrates (Fir āt)—two of southwestern Asia’s principal...

• Hawaii (state) - geography.

  limestone along the coast. The volcanoes of the Hawaiian Islands are all so-called shield volcanoes, or lava domes. Unlike the volcanoes of Alaska and South America, those of Hawaii were notcreated by very explosive eruptions. Formed mostly by lava flows, they are great rounded mountain masses, rather than steep-sided cones. Mauna Kea, dormant forcenturies, is the highest mountain in the state. It rises to 4,205 m (13,796 ft) above sea level, and its summit is dotted with cinder cones formed by...

• Hawaii (state) - USA History.

  limestone along the coast. The volcanoes of the Hawaiian Islands are all so-called shield volcanoes, or lava domes. Unlike the volcanoes of Alaska and South America, those of Hawaii were notcreated by very explosive eruptions. Formed mostly by lava flows, they are great rounded mountain masses, rather than steep-sided cones. Mauna Kea, dormant forcenturies, is the highest mountain in the state. It rises to 4,205 m (13,796 ft) above sea level, and its summit is dotted with cinder cones formed by...