UNIT SIX

6. SOILS, NATURAL VEGETATION AND WILDLIFE RESOURCES OF ETHIOPIA AND THE HORN

6.1. Introduction

• Ethiopia's historical geological processes and climatic variations have resulted in varied soil and biological diversity.

  • Distribution of wildlife and natural vegetation is influenced by:

    • Climate

    • Soil types

    • Drainage

• Ethiopia is home to many unique endemic fauna and flora resources.

6.2. Soils of Ethiopia

6.2.1. Major Components, Formation & Properties of Soils

• Composition of soil includes:

  • Weathered Mineral Materials (45%)

  • Organic Matter (5%)

  • Air (20-30%)

  • Water (20-30%)

• Soil Formation:

  • A long-term process, taking thousands of years.

  • Influenced by:

    • Climate and topography

    • Parent material (rocks)

    • Living organisms

    • Vegetation cover

    • Time

6.2.2. Weathering and Soil Formation

• Weathering: Breakdown of rocks into smaller soil pieces through:

  • Frost action

  • Rainwater action

  • Extreme temperature variations

  • Biological activity

• Types of weathering:

  1. Mechanical (Physical) Weathering:

     • Physical disintegration of rock without changing composition.

     • Involves:

       • Differential stresses

       • Frost action

       • Abrasion (erosion by friction)

  2. Biological Weathering:

     • Weakening and disintegration from biological agents:

       • Plant roots

       • Burrowing animals

       • Microbes (bacteria and fungi)

  3. Chemical Weathering:

     • Disintegration through chemical reactions, altering composition.

     • Major reactions include:

       • Carbonation

       • Dissolution

       • Oxidation

       • Hydrolysis

6.2.3. Soil Properties

• Physical Properties:

  • Texture, structure, porosity affecting air and water movement.

• Chemical Properties:

  • Availability of minerals, electrical conductivity, soil pH.

6.2.4. Soil Types and Agriculture Suitability

• Ethiopian soils derived from:

  • Crystalline, volcanic, and Mesozoic sedimentary rocks.

• Soil Types (FAO classification): 18 soil types, major ones cover 87.4% of land area.

6.2.4.1. Nitosols

• Develop on gently sloping ground in highlands with high rainfall.

  • Strongly weathered, high leaching, reddish-brown color due to iron oxides.

  • More productive than most tropical soils.

  • Found in:

    • Western Highlands (Wellega)

    • Southern/Central/Eastern Highlands

6.2.4.2. Acrisols

• Associated with high rainfall highland areas.

  • Low productive capacity, known for nutrient loss.

  • Found alongside nitosols in SW highlands.

6.2.4.3. Vertisols

• Found in highlands and moderate climates.

  • Heavy clay soils, prone to swelling and cracking.

  • Develop from volcanic basalt and sedimentary rocks.

  • Found in NW, Central, and SE Highlands.

6.2.4.4. Xerosols & Yermosols

• Desert soils in arid areas, characterized by high salt content and low organic matter.

  • Fertility improved by irrigation.

6.2.5. Soil Degradation in Ethiopia

• Definition: Deterioration of soil properties (physical, chemical, biological).

• Types:

  1. Physical Degradation: Includes compaction and soil erosion.

  2. Biological Degradation: Loss of organic matter, carbon, and soil fauna.

  3. Chemical Degradation: Nutrient depletion, toxic chemical buildup.

6.2.6. Soil Erosion Control Measures

• Aim: Reduce erosion for sustainable agricultural production without environmental damage.

  • Major control mechanisms:

    • Biological Control:

      • Vegetative strips

      • Afforestation and reforestation

    • Physical Control:

      • Terracing, check dams, contour ploughing.

6.3. Natural Vegetation of Ethiopia

6.3.1. Introduction

• Natural Vegetation (NV): Plant cover with minimal human interference.

  • Controlled by: altitude, climate, and drainage.

  • Estimated 6000 species of plants, with 10% endemic.

6.3.2. Major Natural Vegetation Types

• 1. Afro-alpine and sub-afro-alpine Region

• 2. Forest Region

• 3. Woodland Savanna Region

• 4. Steppe Vegetation Region

• 5. Semi-Desert Vegetation Region

6.3.3. Key Vegetation Types

• Afro-Alpine: Found between 3,200-4,620 m; characterized by tussock grasslands and lichens.

• Forests: Vary from humid to arid; characterized by distinct flora.

• Woodland Savanna: Xeromorphic characteristics; trees shed leaves in dry season.

6.3.4. Degradation of Natural Vegetation

• Major causes:

  • Forest clearing for agriculture

  • Timber exploitation

  • Overgrazing and urban expansion.

6.4. Wildlife Resources of Ethiopia

6.4.1. Species Overview

• Birds: 860 species (16 endemic).

• Mammals: 279 species (31 endemic).

  • Includes Walia Ibex, Gelada Baboon, and Ethiopian Wolf.

6.4.2. Importance of Wildlife

• Ecological, economic, and recreational values.

• Used for scientific research and promoting tourism.

6.4.3. Conservation Efforts

• Protected areas established:

  • National parks and sanctuaries where legal hunting is regulated.

• Challenges faced in protected areas:

  • Human expansion, overgrazing, illegal wildlife trade.