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Changing Vegetation in the Savanna:
Supplementary Material to Lesson 4 of the “East Africa Climate Change Curriculum Unit”
Available at http://www.eaclipse.msu.edu/teaching_materials.html
Lesson 4 by Dwight Sieggreen & Barbara Naess. PowerPoint based on presentation by Jennifer M. Olson,
2008.
The Eaclipse Project is supported by
National Science Foundation Award No. BCS/CNH 0709671.
http://eaclipse.msu.edu
1© 2010 Michigan State University Board of Trustees
Lesson 4: Changing Vegetation in the SavannaSupplementary Material
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Rising Temperatures in East Africa
Inland Coast
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Arusha 1961-2005 (+1.1°C)Arusha mean annual temperature time series (1961 -2005)
y = 0.0248x - 29.127
R2 = 0.5132
18.5
19.0
19.5
20.0
20.5
21.0
21.5
1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009
Years
Tem
pera
ture
(C)
Annual Linear Trend
Zanzibar 1961-2005 (+1.9°C)Zanzibar annual mean temperature time series (1961 - 2005)
y = 0.0423x - 57.902
R2 = 0.5755
23.0
23.5
24.0
24.5
25.0
25.5
26.0
26.5
27.0
27.5
28.0
1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009
Years
Tem
pera
ture
(C)
Annual mean Linear Trend
Source: Tanzania Meteorological Agency
Variable Rainfall in East Africa
Inland Coast
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Arusha 1961-2005Arusha annual rainfall time series (1961 -2005) y = -6.2175x + 13146
R2 = 0.0799
0
200
400
600
800
1000
1200
1400
1600
1800
1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009
Years
Rain
fall
(mm
)
Annual rainfall Linear Trend
Zanzibar 1961-2005Zanzibar annual rainfall time series (1961 -2005)
y = -0.792x + 3251.6
R2 = 0.0007
0
500
1000
1500
2000
2500
3000
1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009
Years
Rai
nfal
l (m
m)
Annual rainfall Linear Trend
Source: Tanzania Meteorological Agency
While climate change is affecting all of East Africa, the savanna is the most vulnerable ecosystem in East Africa
Savanna vegetation is highly vulnerable to changes in temperature and moisture availability
These changes affect people’s ability to grow crops and keep livestock in the savanna (livelihood)
The EACLIPSE Project focuses on the savanna in order to have the greatest possible impact 5
Changing Vegetation
In this lesson, you will
• look at how changes in temperature and water availability affect savanna vegetation and
• make predictions as to how these changes might affect people’s choices of livelihoods and land use
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The savanna is a biome defined as a tropical grassland with scattered shrubs and trees.
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Temperature vs. Precipitation Biome Graph
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Source: The Wild Classroom. http://www.thewildclassroom.com/biomes/precipitationgraph.html
Ecological Zones in East Africa• Rainfall and evaporation determine moisture availability
• High temperatures speed up evaporation and evapotranspiration, decreasing moisture availability
• In East Africa, seven ecological zones have been described based on moisture availability and temperatures.
• Three of these zones (IV, V, and VI) include the savanna 9
Source: Kenya Ministry of Agriculture 1980: Agro-climatic zone map of Kenya 1980
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Table based on: Kenya Ministry of Agriculture 1980: Agro-climatic zone map of Kenya 1980
Source: Pratt, Greenway and Gwynne, 1966. A Classification of East African Rangeland. Journal of Applied Ecology, 3, 2: 369-382.
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Zone IV: Dry Woodland and Bushland
Higher moisture availability
Taller trees
More ground cover
Better growing conditions
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Zone V: Bushland
Lower moisture availability
Scattered shrubs
Medium ground cover
Poor growing conditions
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Zone VI: Bushland and Scrubland
Low moisture availability
Infrequent shrubs or scrub
Less ground cover
Very poor growing conditions
Changes in Savanna Vegetation
Moisture availability will impact:• crops• livestock• wildlife habitats
…affecting people’s livelihood options and land use
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Impact on Crops
• Timing of planting and harvest• Length of growing season• What crops can be planted, where• Whether some areas will be suitable for
farming• Lower crop yields (productivity)• Greater risk of crop failure
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Impact on LivestockWhen there are higher temperatures and less moisture
availability:• vegetation dries out faster• water becomes scarce• ground cover decreases (less forage for livestock)• forage grows less quickly (lower productivity)• forage species are of lower quality (palatability)• droughts are more often
and more severe• livestock diseases
are more frequent
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Impact on Wildlife Habitats• Many wildlife are sensitive to changes in temperature
and to water availability• Plants needed by some species may not grow• Wildlife migration patterns may change
The EACLIPSE project is collecting data on changes in climate and ecosystems in East Africa.
The data collected include:
•temperature and rainfall
•plant species, and
•plant density (ground cover)
This information will help researchers predict the effects of climate change and anticipate what kinds of livelihoods and land use might be viable under different conditions.
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Discussion Questions1. How does climate change affect vegetation in the
savanna?
2. What factors affect moisture availability?
3. What happens to savanna vegetation as moisture availability decreases?
4. What would happen if there were not enough moisture available for bushland and scrubland vegetation?
5. How does the changing vegetation affect people’s livelihood/land use options?
6. How does changing vegetation fit into the human-
land-climate system loop?19
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