FTTS F04 Soils Lecture, 18 Oct Page 1 of 2Introduction to Soils: Foundations of EcosystemsWhat is soil?Role of soil in ecosystems1. Medium for plant growth2. Control fate of water3. Recycling system4. Habitat for soil organismsSoil formation is controlled by1. Parent material2. Climatea. Physical weatheringb. Chemical weathering i. Cation Exchange Capacity (CEC)3. Biotaa. Types of Soil Organic Matter (SOM)4. Topography5. TimePhysical composition of soilTexture triangle (p 62)Percent sand, silt, & claySoil ProfilesLayers development over time (p 58)Horizontal and vertical movement within soil profileFTTS F04 Soils Lecture, 18 Oct Page 2 of 2How ecosystems influence soilsVariety of scales Macro to microCapture of solar energy and carbon fixationDeposition of organic material (OM)DecompositionFunctionsSoil microorganismsInfluence of plantsRhizosphereSoils are open systemsWorkshop: Soils in Forests—Temperate vs. Tropical (20 minutes)Form groups of three. Appoint one person to take notes during your discussion. At the end of the discussion,make sure that each person has time to copy down the list of answers you agree upon. Carefully considereach of the following attributes/ factors that influence soils and how they differ between temperate andtropical forests. Briefly outline the differences and the resulting influence you would expect to see in thesoils of forests in these areas. Discuss and list the reasons for your answers.1. Climate2. Plant Biomass3. Decomposition rate4. SOM accumulation5. Degree of weathering6. Relative fertility of soil7. Ability to hold cations & anions8. Major pool (storage) of nutrients9. Soil
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