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Ecosystems & Population Change

Ecosystems & Population Change. 4.5 – Changes in Ecosystems. Change. Occur naturally over time - shift in abiotic /biotic factors - events ie ) fire, flood Human activity - deforestion - pollution. Terrestrial Change - Forests. Area of forests declining Forests affect:

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Ecosystems & Population Change

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  1. Ecosystems & Population Change 4.5 – Changes in Ecosystems

  2. Change • Occur naturally over time- shift in abiotic/biotic factors- events ie) fire, flood • Human activity- deforestion- pollution

  3. Terrestrial Change - Forests • Area of forests declining • Forests affect: • climate: recycling H2O & CO2 • physical environment: • soil erosion, runoff, groundwater • shelter for wildlife • Forestry Practices:- Slash-and-burn: tropical areas (bulldoze)- Clearcutting: remove all trees (succession pg 114)- Selective cutting: removal of certain trees • Amazon Deforestation in Google Earth

  4. Terrestrial Change - Fire • Fires necessary to maintain natural ecosystems • creates & maintains mosaic of vegetation types • Caused by:- lightning- prescribed burns: set intentionally

  5. Aquatic Change - Lakes • Oligotrophic Lakes: low nutrient levels- deep & cold • Eutrophic Lakes: high nutrient levels- shallow & warmer- murkier waters, many organisms • Lake Succession: oligotrophic to eutrophic over time- eutrophication: from low to high nutrient levels

  6. Aquatic Change - Lakes • Eutrophication: occurs natural as part of a lake’s succession • Human activity can also influence this process- increase the rate of eutrophication • Increased addition of minerals and pollutants to systemex) fertilizers on fields – runoff to wetlandsex2) phosphorus in detergents

  7. Water Pollution • Defn: any physical or chemical change in surface water or groundwater that can do harm • Adding nutrients • Accelerates eutrophication • 5 categories- organic solid waste- disease-causing organisms- inorganic solids & dissolved minerals- thermal energy- organic compounds

  8. Indicators of Water Quality • Classified according to its intended use • Bacteria: detection of coliform bacteria- animal waste contamination- dangerous diseases in feces • Dissolved Oxygen: low = fewer organisms- solutions to test (colour change)- type of organisms present are indicator too • Biological Oxygen Demand: amount of D.O needed by decomposers to break down organic matter in 20oC water for 5 days- more organisms = higher BOD, less D.O

  9. Example • Alberta: Lake Muriel- Water level decrease, salinity increase • Watershed: area of land that drains toward body of water- balance of abiotic/biotic factors • Cottage owners alter shorelines, also watersheds- making beaches- removing weeds- outhouses • Increased erosion/eutrophication = speed up aging of lake

  10. Alberta Watersheds

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