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Oct 19, 2023 · Grasslands are habitats with grasses as the dominant vegetation, found on every continent except Antarctica. They are often between forests and deserts, and have different types, plants, and animals depending on rainfall and temperature.
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grassland, area in which the vegetation is dominated by a nearly continuous cover of grasses. Grasslands occur in environments conducive to the growth of this plant cover but not to that of taller plants, particularly trees and shrubs. The factors preventing establishment of such taller, woody vegetation are varied.
Grasslands are one of the most widespread of all the major vegetation types of the world. This is so, however, only because human manipulation of the land has significantly altered the natural vegetation, creating artificial grasslands of cereal crops, pastures, and other areas that require some form of repetitious, unnatural disturbance such as cultivation, heavy grazing, burning, or mowing to persist. This discussion, however, concentrates on natural and nearly natural grasslands.
The most extensive natural grasslands can be thought of as intermediates in an environmental gradient, with forests at one end and deserts at the other. Forests occupy the most favourable environments, where moisture is adequate for growth and survival of a tall, dense vegetation dominated by trees. Deserts are found where moisture is so lacking that a continuous, permanent vegetation cover cannot be maintained. Grasslands lie between these two extremes.
Like the savannas, deserts, and scrublands into which they commonly blend, grasslands arose during the period of cooling and drying of the global climate, which occurred during the Cenozoic Era (65.5 million years ago to the present). Indeed, the grass family itself (Poaceae or Gramineae) evolved only early in this era. The date of earliest appearance of grasslands varies from region to region. In several regions a succession of vegetation types can be recognized in the Cenozoic fossil record, as climate dried out progressively. For example, in central Australia during the past 50 million years tropical rainforest gave way successively to savanna, grassland, and, finally, desert. In some places expansion of grasslands to something approaching their modern extent occurred only during the extremely cold, dry intervals—called ice ages in north temperate regions—of the past two million years.
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Ecosystems
A dynamic balance commonly exists between grasslands and related vegetation types. Droughts, fires, or episodes of heavy grazing favour grassland at some times, and wet seasons and an absence of significant disturbances favour woody vegetation at others. Changes in the severity or frequency of these factors can cause a change from one vegetation type to another.
Other grassland types occur in places too cold for trees to grow—i.e., beyond the forest limits of high mountains or at high latitudes. A characteristic type of grassland in cool, moist parts of the Southern Hemisphere is tussock grassland, dominated by tussock or bunch grasses that develop pedestals of matted stems, giving the vegetation a lumpy appearance. Tussock grasslands occur at various latitudes. In the tropics they are found above the forest limit on some high mountains—e.g., in New Guinea and East Africa. At the higher latitudes of the Southern Ocean they form the main vegetation of subantarctic islands. They are also typical of the drier, colder parts of New Zealand and the southernmost regions of South America.
Grassland climates are varied, but all large regions of natural grassland are generally hot, at least in summer, and dry, though not to the extent that deserts are. In general, tropical grasslands receive 500 to 1,500 millimetres (20 to 60 inches) of rain in an average year and in every season experience temperatures of about 15 to 35 °C (59 to 95 °F). The dry season may last as long as eight months. An excess of rainfall over evaporation, leading to ephemeral river flow, occurs only during the wet season. The tropical grassland climate overlaps very broadly with that of savanna. As previously stated, these vegetation types differ little from each other, a savanna being merely a grassland with scattered trees. Small changes in management and usage can convert one to the other.
Temperate grasslands are somewhat drier than tropical grasslands and also colder, at least for part of the year. Seasonal temperature variation may be slight in tropical grasslands but may vary by as much as 40 °C (72 °F) in temperate grassland areas. Mean annual rainfall in the North American grassland areas is 300 to 600 millimetres. Mean temperatures in January range from −18 °C (0 °F) in the north to 10 °C (50 °F) in the south, with corresponding values in July being 18 °C (64 °F) and 28 °C (82 °F). Mean annual temperature in the most northerly areas of the North American grassland zone is below 0 °C (32 °F).
A grassland is an area where the vegetation is dominated by grasses . However, sedge and rush can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur naturally on all continents except Antarctica and are found in most ecoregions of the Earth.
Aug 26, 2020 · Grasslands are regions where grasses dominate the plant growth, covering about 30-40% of Earth's land area. They occur on every continent except Antarctica, and have diverse climates, soils, and wildlife.
Mar 14, 2019 · Grasslands are open habitats with grasses as the dominant vegetation. They occur on every continent except Antarctica, and vary in rainfall, temperature, and biodiversity.
Apr 24, 2024 · Grasslands — also known as savannas, prairies, steppes and pampas — are ecosystems found in parts of the world that do not get sufficient consistent rainfall to support forest growth, but get enough to avoid the landscape turning into desert. Often, grasslands are a transition ecosystem between deserts and forests.
