Transcript temperate grasslands-craig-

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