Craig Christensen March 5, 2009 Development Studies TEMPERATE GRASSLANDS WHAT ARE THEY? An ecotone A transitional zone between two different ecosystems Areas where precipitation is high enough to sustain grass, but (sometimes) only a few trees. Occur between forested and desert areas. WHERE? * All occur in temperate regions (beyond 23.5 degrees North or South of the Equator.) WHAT ARE THEY CALLED? 1.- Central/North America - Plains and Prairies 2.- Argentina Pampas 3.- Hungary Puszta 4.- Russia Steppes 5.- Australia Downs 6.- New Zealand Downs 7.- South Africa Veldts CLIMATE Continental climate due to location Hot summers, up to 30°C, below freezing for up to six months continuous. Low ppt. (250-750mm annual) convectional rain in summer, snow in winter High evaporation rates in summer Periods of drought, and torrential rain can occur SOIL Chernozem soils Thick humus layer Calcium carbonate deposits Leaching during spring (snowmelt), and capillary rise in summer Deeps roots and flat relief minimize erosion VEGETATION Mainly grasses, with sparse bushes and trees Height of grass relates to amount of precipitation Vegetation is xerophytic and pyrophytic NPP = 600g/m2/yr Biomass = 1.6kg/m (low due to lack of trees) FAUNA Considering harsher climate, and lower availability of energy from primary producers, zoo-diversity quite low. Species include: Hoofed mammals (pronghorn, bison) Ground rodents (prairie dogs) Small carnivores (coyote, badgers, weasels) Decomposers crucial in mixing soil. NUTRIENT MOVEMENTS Largest reserve of nutrients is in Soil Very little lost to run-off and leaching Fire is important in returning nutrients to the soil. CASE STUDY: CANADIAN PRAIRIES FLORA AND FAUNA Grass species include: Many small bushes: Spear grass, wheat, barley, thread grass Saskatoon, choke cherry, aster Being on the edge of the ecotone, isolated forest communities exist, especially in Northern and Eastern limits. Dedicious species : birch, willow, elder, aspen, poplar Coniferous species : Spruce SPECIAL CHARACTERISTICS Local topography can affect ecosystem River valleys often have forest Occasional deserts in valleys (Badlands) SPECIAL CHARACTERISTICS Climactic Hazards Convectional summer rainfall can cause damaging hail and occasional tornadoes Ex. Black Friday, summer ‘04 in Edmonton Extreme winter cold (down to -40°C) troublesome for keeping livestock HUMAN IMPACT 95% of original, natural prairie has been converted to agricultural land. Little natural prairie remains. Hunting of bison left only 250 wood bison at the end of the 19th century Extinction and extirpation of many native species. Introduction of pests Swift fox Dandelion Colony Collapse disorder and bees 30-70% losses reported in Winter ’06’07 Bees add $15 billion to US economy; similar impact could be felt SOURCES http://www.runet.edu/~swoodwar/CLASSES/GEOG235/biomes/tempgrass /tempgras.html http://www.eldoradocountyweather.com/canada/climate/medicinehatclima te.html http://canadianbiodiversity.mcgill.ca/english/ecozones/prairies/prairies.ht m# http://www.srd.gov.ab.ca/fishwildlife/status/bison/index.html http://www2.canada.com/edmonton/edmontonjournal/news/story.html?id =b9fa4403-a7f9-40b8-bcb9-f8a8f6966968 http://www.ars.usda.gov/News/docs.htm?docid=15572