#17 Grasslands Flashcards
Grasslands occupy regions where rainfall is between ______?
25 and 60cm/year
Natural grasslands have shrunk to less than ___% of their original size
12%
Many grasslands exist through the intervention of ____ and ______?
fire and human activity
Grasslands occur in ______ regions, where annual precipitation is ______?
mid-continental; reduced
what type of grassland experiences recurring drought?
temperate grasslands
grasslands do poorest when precipitation is ____ and temperatures are __?
lowest; high
Grasslands are most productive when mean annual precipitation is greater than _____ mm and mean annual temperature is above ___ degrees Celsius
800mm; 15 degrees Celsius
grazing stimulates primary production (true or false).
true
what are the major consumers in grasslands?
invertebrates, heaviest consumption takes place in the soil by nematodes.
What are the six major North American Grasslands. What distinguishes them apart?
- mixed grass prairie
- tall grass prairie
- short grass prairie
- desert grassland
- Palouse grassland
- California annual grassland
the six types are based on the height of dominant species, reflecting precipitation and temperature
how many species does it take to characterize a grassland?
3-4 species characterize a grassland and produce majority of the biomass
what are some pros and cons of the ground layer in grassland ecosystems
the thick layer of mulch (litter) is a good place for decomposition.
- enhanced soil moisture through infiltration and evaporation
- reduced runoff and erosion
- stabilize soil temperature
- improves seed germination
- too much will reduce plant growth
How much biomass does the below ground root layer represent?
How many soil root zones are there?
- represents more than half of the biomass
- Three or more horizons
