Temperate Grasslands

Produced by Michael G, former colleague. Good outline of temperate grasslands, with some Google Earth images of the steppes.

1. Grassland Biomes
location, structure and functions

2. The 8 major biomes of
the world

3. The temperate grassland biome
Prairies of
North America
Pampas of
South America Veldt of
South Africa
Russian /
Mongolian Steppes
Australian
Bush
Canterbury
Plains, NZ

4. Steppe terrain in Russia and Mongolia
•Undulating land dominated by
grasses
•Large trees and shrubs are
mainly absent

5. Steppe climate
What do you think the general climate is like
throughout the year and why? (think about
factors such as latitude)
Cool temperate climate for steppe grasslands
(warm temperate climate for Veldt)

6. Steppe climate
What annual temperature range would you
expect and why? (think about factors such as
continentality)
Mean annual temperatures ranging from –15 in
winter to +20 in summer. Continental interior
results in low temperatures during winter.

7. Steppe climate
How important would you think precipitation is
for grassland biomes? Why? Would they be
high rainfall biomes? Why / why not?
Precipitation is a dictating factor on grassland
biomes and grass type – more rain generally
means taller grasses. Low precipitation (not
enough for trees) of around 250-500mm per
year. More precipitation in western steppe
than in east as there are less rain-bearing
winds. 75% of all precipitation falls during the
summer months.

8. Typical Steppe climate graph

9. What problems could this factor of low precipitation bring?
Threats of drought and fire.
Steppe climate

12. Temperate grassland soils
Chernozem (black earth) type
•Very deep, dark in colour with fertile upper layers
•Nutrient rich from decay of surface matter in winter and
due to decay of deep, wide-branching roots – especially
important for recycling of Ca.
•Approx 2m-deep grass rooting system helps keep the
soil structure stable and intact (tightly-knit ‘sod’)
reducing soil erosion and protecting underground stems
and buds from winter frost and snow.
•Roots reach right down to the water table so there is a
net upward movement of water.
•Ideal soils for farming but prone to wind erosion if
ecosystem balance is not maintained.

13. A Horizon 0-50cms
Organic matter on top. Strong drying
action by winds. Crumbly black
topsoil. Matted, random root network
with accumulation of mull humus and
bases Ca, Ng, Na, K and some Fe,
Al and Si. Grasses extract and return
minerals. Many biota such as
earthworms – nutrient mixing and
aids drainage.
B1 Horizon 50-100cms
Fine vertical roots. Slight leaching of
nutrients especially after spring snow
melt and summer storms. Loess
B2 Horizon 100-160cms
Calcification occurs - nodules of
CaCo
3
form. Loess
C Horizon 160-200cms
weathered parent rock
Lime-rich parent rock 200cms

14. Last lesson …
•Where are the major areas of grassland biomes to be found?
•In terms of climate, what type of biome is Steppe?
•What did we find out about the climate in the Steppe biome?
•What type of soil is generally found in this area?
•Are these soils infertile? Why / Why not?

15. Why no trees?
•Thick grass cover – prevents tree seeds from taking hold.
•Low precipitation inhibits tree growth.
•Fire destroys any trees that may take hold – underground
stems and buds of perennial grasses not affected by fire
(as opposed to trees and shrubs that have above-ground
stems and buds).
•Grazing animals quickly destroy emerging shrubs and
sapling trees.
•Grasses are hardy and quick growing.

16. Steppe biodiversity
Low flora and fauna
diversity when compared
with tropical grasslands
such as savanah.
•Blue gramma and buffalo grass
•Sagebrush and speargrasses

17. Flora
What advantages do you think
these grasses have for survival in
the environment that they live in?
•Narrow, spine-like leaves
•Waxy or downy surfaces
•Long, water-seeking roots
•Below-ground stems and buds
•Seeds easily dispersed by wind
•Some grasses and their seeds release
inhibitory chemicals

18. Fauna
Lower biodiversity than
tropical grasslands …
Small mammals
(mainly rodents)
•Gophers
•Rabbits
•Foxes
Other mammals
•Goats, antelope
•Horse
Also
•Reptiles
•Birds
•Many insect varieties

19. GPP and NPP in temperate
grasslands
•Gross primary productivity is the amount
of energy trapped in organic matter during
a specified interval at a given trophic level.
•Net primary productivity is the amount of
energy trapped in organic matter during a
specified interval at a given trophic level
less that lost by the respiration of the
organisms at that level.

20. Tropical rainforest – 15000 Kcal/m
2
/yr
Comparative NPP rates in
different biomes
Temperate forest – 5000 Kcal/m
2
/yr
Temperate grasslands– 2000 Kcal/m
2
/yr
Desert – 500 Kcal/m
2
/yr

21. Nutrient Cycling
•In addition to energy, ecosystems also contain cycles of nitrogen
and other plant nutrients, such as phosphates and potassium.
•The pattern of plant nutrients can be shown as a diagram. Nutrients
are derived from weathered rock or in dissolved in rainfall and
they may be lost from the system by leaching, in runoff or through
harvesting of crops.
•Most nutrients are recycled within the system through plant uptake,
leaf fall (and other “fallout” from plants and animals) and
decomposition.
•Nutrients are stored in the biomass, the litter and the soil in
variable quantities depending on the type of ecosystem and
seasonal changes.

22. Mineral recycling

24. L
B
S
B
L
S
Tropical rainforest Steppe nutrient storage
nutrient storage

25. S
B
L
Input dissolved
in rainfall
Release as litter
decomposes
Uptake by
plants
Loss in
runoff
Fall out as
tissues die
Input weathered
from rock
Loss by
leaching