chapter 4 v1.3 - universiteit twente · – wildlife culling +/‐ ... major natural vegetation...
TRANSCRIPT
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Chapter 4
Distribution and ecology of trees in east African drylands
Thomas A. Groen (Twente University)Roeland Kindt (ICRAF)
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Chapter 4Set‐up so far:• What are the definitions of
(to be defined in concordance with workshop attenders):– Aridity (Aridity indices, which one to use?)– Trees (structural, functional, ecological)– Tree lands/Shrublands (physiognomy…
• What determines tree cover– Abiotic factors (rainfall, soil etc…)– Biotic factors (herbivory, fire)– Human interference with these factors
• Distinct vegetation types with trees in arid lands– Species composition of these types– Distribution in East Africa– Relative importance in the different countries– Usage by humans
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Talking about tree cover
Next to tree cover:• Total Biomass• Tree Height• Canopy density• Number of trees• Stem diameter• Species type
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What determines tree cover• Abiotic factors
– Rainfall +– Soil +/‐– Temperature ‐– [CO2] C3 trees vs C4 Grasses +
• Biotic factors – Competition with grass ‐
– Herbivory• Grazing +
• Browsing ‐– Fire ‐
• Human interference– Harvesting ‐
• Leaves• Fruits• Branches• Clear cut
– Livestock raising +/‐– Wildlife culling +/‐
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What determines tree cover
– Abiotic factors (rainfall, soil etc…)
Source: Sankaran et al. 2005 Source: Staver et al. 20
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What determines tree cover
What determines tree cover
Source: Bertram and Dewar 2013
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What determines tree cover
Source: Staver et al. 2012
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What determines tree cover
• Biotic factors (herbivory, fire)
Source: Van Langevelde et al. 2003
grass
Source: http://www.lonelyplanet.com/blog/2009/10/23/goats‐in‐trees/
Source: http://www.fire.uni‐freiburg.de/photos/za/za.htm
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What determines tree cover
Source: http://www.crlonghorns.com/Default.aspx?id=8277
http://www.adventurecampstz.com/PHOTOGALLERIES/Ruaha/Ruaha%20Other%20Animals/pages/24%20Kudu%20horns,%20Ruaha_jpg.htm
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What determines tree cover
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What determines tree cover
Source: Staver et al. 2012
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Major natural vegetation types in the Horn of Africa
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Somalia‐Masai Acacia‐Commiphora deciduous bushland and thicket
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Somalia‐Masai Acacia‐Commiphora deciduous bushland and thicket
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Somalia‐Masai semi‐desert grassland and shrubland
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Somalia‐Masai semi‐desert grassland and shrubland
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Somalia‐Masai East African evergreen and semi‐evergreen bushland and thicket /secondary (biotic) Acacia wooded grassland
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Somalia‐Masai East African evergreen and semi‐evergreen bushland and thicket /secondary (biotic) Acacia wooded grassland
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Drier Zambezian miombo woodland (yellowish)Wetter Zambezian miombo woodland (greenish)
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Drier Zambezian miombo woodlandWetter Zambezian miombo woodland
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Sudanian undifferentiated woodlandSudanian woodland with abundant Isoberlinia
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Sudanian undifferentiated woodlandSudanian woodland with abundant Isoberlinia
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Decision‐support tools for species selection
“ICRAF have a nifty new tool out called Useful Tree Species for Africa. I’ve been playing around with it and I have to say it’s impressive.”Luigi Guarino http://agro.biodiver.se/)
http://www.worldagroforestrycentre.org/our_products/databases
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VECEA: A higher resolution map for 7 countries in eastern Africa(Ethiopia, Kenya, Malawi, Rwanda, Uganda, Tanzania and Zambia)
http://www.vegetationmap4africa.org
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VECEA: A higher resolution map for 7 countries in eastern Africa(Ethiopia, Kenya, Malawi, Rwanda, Uganda, Tanzania and Zambia)
http://www.vegetationmap4africa.org
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VECEA: A higher resolution map for 7 countries in eastern Africa(Ethiopia, Kenya, Malawi, Rwanda, Uganda, Tanzania and Zambia)
http://www.vegetationmap4africa.org
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Agroforestry Species Switchboard(coming soon)
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Chapter 4
Distribution and ecology of trees in east African drylands
Thomas A. Groen (Twente University)Roeland Kindt (ICRAF)