Geography and Environment Jahangirnagar University, Savar, Dhaka. 2013 Temperate Grasslands Sonia Nazneen (sonianazneen1991@gmail.com)  Temperate Grasslands Introduction: Temperate grasslands are composed of a rich mix of grasses and forbs and underlain by some of the world’s most fertile soils. Since the development of the steel plow most have been converted to agricultural lands. Grasslands: Regions with enough average annual precipitation to allow grass to prosper but with precipitation so erratic that drought and fire prevent large stands of trees from growing. Types of Grasslands Three Main Types of Grasslands  Tropical  Temperate  Polar (tundra) A short description of temperate grasslands is shown here- Temperate Grasslands: Temperate grasslands are a division of a larger biome grouping of grasslands that includes tropical savannas. Both biome types are characterized by a dominance of grasses, yet temperate grasslands differ significantly from savannas. First unlike savannas that can have trees and shrubs scattered throughout, temperate grasslands have trees and shrubs absent. Temperate grasslands are also found in less tropical ecosystems and thus have a larger temperate fluctuation during the year. Temperatures in temperate grasslands can vary tremendously which has a large impact on growing seasons. Generally they also have less rainfall. Art Explosion Art Explosion Rolling hills covered with grasses and very few trees are typical of North American grassland prairies. A few scattered trees are found on savannas, tropical grasslands of Africa. Location: Temperate Grasslands are found throughout the globe, generally in the interiors of the continents and north or south of the tropic of cancer/caper corn.  The following are the major regional expressions of grasslands recognized around the globe. Veldts of South Africa Puszta of Hungary Pampas of Argentina/Uruguay Steppes of Russia / China Plains and Prairies of North America Argentina – pampas Downs of Australia The Canterbury Plains in New Zealand Steppes of Russia Fig: Temperate Grasslands Minor Expressions: There are smaller local expressions of grasslands as well. These include the following: Australian Outback Minnesota Cedar Creek Region Fig: Temperate Grasslands Structure:  Temperate grasslands can be divided into tall-grass areas and short-grass areas. Tall grasses that are taller than two meters are usually found in wetter regions while short grasses that are shorter than sixty centimetres can be found in drier regions. The typical species of grasses are Andropogon, Panicum and Stipa and some herbs can be found between them. Trees are rare in the temperate grasslands because there is not enough moisture for them to grow as they have longer life cycles and need longer growing season than grasses.   Climate Temperatures in temperate grasslands vary according to the season. Temperate grasslands have a temperate continental climate, which is cooler than savannas. Temperate grasslands have warm, humid summers with an average temperature of 18° C and cool, dry winters with an average temperature of 10° C. Temperate grasslands receive low to moderate precipitation on average per year (20-35 inches). Most of this precipitation is in the form of snow in temperate grasslands of the northern hemisphere. Rainfall: Rainfall is generally less in temperate grasslands than in tropical savannas, although drought usually plays less of a roll effecting biodiversity than it does in savannas. Rain usually falls in temperate grasslands in the late spring and early summer. There is an average of 20 – 35 inches of rainfall a year. The amount of rainfall however determines the height of grasses in the grassland. For north America, this rainfall gradient helps to divide the temperate grasslands into tall grass prairies (in wetter areas) and short grass steppes (in dryer habitats). Drought: Drought plays a large role in keeping trees from taking over the grasslands. Some years receive less rain than others, just as certain seasons receive significantly less rain than others. Trees generally cannot stand the lack of water as easily as grasses and thus grasses remain dominant. Vegetation Low to moderate precipitation makes temperate grasslands a difficult place for tall plants such as woody shrubs and trees to grow. Grasses of this area have adapted to cold temperatures, drought, and occasional fires. These grasses have deep, massive root systems that take hold in the soil. This allows the grasses to remain firmly rooted in the ground to reduce erosion and to conserve water. Temperate grassland vegetation can either be short or tall. In areas that receive little precipitation, grasses remain low to the ground. Taller grasses can be found in warmer areas that receive more rainfall. Some examples of vegetation in temperate grasslands include: buffalo grass, cacti, sagebrush, perennial grasses, sunflowers, clovers, and wild indigo. Fig: Temperate Grasslands Grasses: Perennial grasses, with their growth buds at or just below the surface, are well adapted to drought, fire, and cold. The tiller or narrow, upright stem reduces heat-gain in the hot summers; the intricate root systems trap moisture and nutrients. Two basic types are: Turf- or sod-forming grasses, with rhizomes or underground stems from which new plants spring forth; associated with the more humid grasslands Bunch grasses, without rhizomes, that reproduce by seed; associated with the drier parts of the biome. Soils: Calcification is the dominant soil-forming process in semiarid regions. Mild leaching, high organic content, and concentration of calcium carbonate in the B horizon typifies the dark brown mollisols developed under the temperate grasslands. When this process works on a loess that itself is rich in calcium, the world’s most fertile soils are created, the chernozems (A Russian term meaning black soil). Loess and hence chernozem underlie the eastern prairies of the US, the pampas of South America, and the steppes of Ukraine and Russia. Art Explosion Art Explosion The rich soils make ideal farmland. Overuse of the land can deplete the soil of vital nutrients. Biodiversity: Grasslands (temperate) are dominated by one or a few species of grasses while there are several hundred other types of grasses and non-woody flowering plants that while less abundant make up a vital part of the species composition. There are many types of grass species that are dominant species in their own region. Each species of grass grows better with varying temperatures / rainfall / and soil conditions. Grasses are dominant (instead of trees) because of fire, drought and grazing by large herbivores. Fig: Biodiversity of Temperate Grasslands Floral Diversity: The most common grasses include blue gamma grass, buffalo grass, Johnson grass, and various sorts of wheat and burley. Common flowers include types of asters, coneflowers, Solidagos (goldenrods), vetches, Indian blankets and sweet clovers. Fauna Diversity: In North America common animals include: bison, pronghorns, deer, mice, rabbits, grouse, badgers, skunks, meadowlarks, various owls, garter snakes, rattle-snakes, red-tailed hawks and prairie dogs. Art Explosion Art Explosion Prairie dogs build extensive networks of tunnels underground. Pronghorn antelope are found grazing grasslands across western North America. Courtesy of John and Karen Hollingsworth, U.S. Fish and WildlifeSservice Courtesy of Ken Stansell, U.S. Fish and Wildlife Service There are several species of rhinoceros: black, white, Javan, Indian, and Sumatran. All are listed as endangered by the International Union for the Conservation of Nature and Natureal Resources. Once numerous in eastern and southern Africa, they are now found only in national parks and game Giraffes are found in the African savanna south of the Sahara Desert. Giraffes feed almost exclusively on the leaves of acacia, mimosa, and wild apricot trees. They drink only rarely, taking in approximately 8 liters (2 gallons) of water in a week, and can go a long time with no water at all. Prairies Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, Brazil and Uruguay as well as the steppes of Eurasia. Lands typically referred to as "prairie" tend to be in North America. The term encompasses the area referred to as the Interior Lowlands of the United States, Canada and Mexico, which includes all of the Great Plains as well as the wetter, somewhat hillier land to the east. In the U.S., the area is constituted by most or all of the states of North Dakota, South Dakota, Nebraska, Kansas, and Oklahoma, and sizable parts of the states of Montana, Wyoming, Colorado, New Mexico, Texas, Missouri, Iowa, Illinois, Indiana, Wisconsin, and western and southern Minnesota. The Central Valley of California is also a prairie. Fig: Temperate Prairies Grasslands Steppe: In physical geography, a steppe is an ecoregion, in the montane grasslands and shrublands and temperate grasslands, savannas, and shrublands biomes, characterized by grassland plains without trees apart from those near rivers and lakes. The prairie (especially the shortgrass and mixed prairie) is an example of a steppe, though it is not usually called such. It may be semi-desert, or covered with grass or shrubs or both. The term is also used to denote the climate encountered in regions too dry to support a forest, but not dry enough to be a desert. The soil is typically of chernozem type. Steppes are usually characterized by a semi-arid and continental climate. Extremes can be recorded in the summer of up to 40 °C (104 °F) and in winter, –40 °C (–40 °F). The mid-latitude steppes can be summarized by hot summers and cold winters, averaging 250–500 mm (10-20 inches) of precipitation per year. Precipitation level alone is not what defines a steppe climate. Fig: Temperate Steppes Grasslands Steppes Temperate Grasslands: Cold steppe Subtropical steppe Environmental concerns: There is a great concern for remaining grasslands in temperate regions. Because the soil in these areas is incredibly rich and the land is flat and treeless, most of this biome has been turned into farms or ranches. The result of this overuse and consumption of the grassland by agricultural practices is a fragmentation of once large tracks of grassland. Fragmentation decreases biodiversity (Theory of Island Biogeography). Plowing of grasslands, combined with wind has lead to huge dust storms, such as those which created the Great Dust Bowl in the American Depression of the mid 1920s. Finally, in dryer areas, overgrazing and salt build-up from irrigation of the land have turned these areas into near-wastelands. Ecological condition Literature that specifically measures or describes the condition and/or viability of Natural Temperate Grasslands is noted. The condition of a site is inextricably linked to its ecological viability. There is a lack of recent data on the condition of grasslands and a virtual absence of studies pertaining to ecological viability. Ecological viability is a complex concept and there are no set guidelines with which to measure it. Ecological viability could be based on any number of attributes of a site depending on the available resources. An obvious difficulty is that viability implies maintenance over time and few long-term studies exist for grasslands . However, information on several ecological characteristics of a site, along with current ecological knowledge, can be used to form a qualitative assessment of the likelihood of vegetation community persistence. Examples of useful characteristics are the extant vegetation structure, patch size and threats. It is important to recognize that a viable site is not necessarily one that is in excellent condition but one that can persist into the future in either the current condition or some improvement of it. Threats: Lists threats identified in the literature as particularly relevant to the region. It is likely that all.\Natural Temperate Grasslands face a similar suite of threats (eg. inappropriate fire régimes, neglect, and weed invasion) but some will be peculiar to certain areas. All Natural Temperate Grassland is under some threat to its long-term viability. Degrading disturbances even occur in permanent reserves. Many grassy remnants are also under severe and immediate threat due to their isolation and continuing changes in land use and land management practices. As a result of discontinuation of Aboriginal and faunal impacts, structural and floristic changes may have already occurred in many remnants. Alteration of species composition and community structure also occurs via heedless management practices and invasion by weeds. Other threatening processes include continuing urban expansion and clearance for agricultural purposes. The impacts of these threats have often been exacerbated by a general lack of interest, while others are threatened by ‘over interest’ where inappropriate tree-planting in native grasslands reduces the richness of the grassy layer. Conclusion: The Temperate grasslands of the world, known variously as the prairie in North America, the pampas in South America, the steppes in eastern Europe and northern Eurasia, and the grassed in South Africa, are among the most diverse and productive of all the earth’s terrestrial biomes. Yet, without exception, temperate grasslands have received very low levels of protection. According to the 1993 United Nations List of National Parks and Protected Areas, only 0.69% of the temperate grasslands biome is under some kind of protective status. Citations Mathur , H.s, Essentials of Biogeography,2004,Pointer Publishers Jaipur. http://images.google.com http://www.deepcreektimes.com/kids/world_grasslands_map. http://images.google.com/imgres http://www.fws.gov/midwest/EcosystemConservation/savanna.jpg http://www.larry-bolch.com/Alberta-Skies/images/Prairie-01.jpg http://www.blueplanetbiomes.org/prairie.htm http://www.blueplanetbiomes.org/savanna.htm