✔ 1. What are some types of natural vegetation?✐ 2. How are forests useful to humans? 3. What happens if we overuse forests?
By the end of the lesson,You should be able to: – List and elaborate three uses of forests. Looks manageable? Lets start!
Functions/Uses of the forest1. Maintains water supply 6.Habitat for life2. Replenishes oxygen, b) maintains the quality 7. Provides timber, fuel, of water supply removes carbon dioxide medicine, food, chemicals3. Maintains nutrients in quantity a) maintains the the soil of water supply Recreation 8.4. Prevent floods 9. Research and education5. Protect coasts
a) maintains the quantity 1. Maintaining water supply of water supply through transpiration 2. Water vapour condenses into tiny droplets of water in the atmosphere and form clouds. 3. The clouds precipitate as rain when they have too much water to hold. 1. Forests release large amounts of water vapour into the4. The rain that falls atmosphere throughreplenishes the water in transpiration.rivers and reservoirs.
b) maintains the quality1. Maintaining water supply of water supply through i) filtering it Soil traps and filters impurities in rainwater and in waste water (such as dead animals, rubbish, human waste) that seeps underground before it flows into rivers and reservoirs. → This water is thus relatively clean
b) maintains the quality1. Maintaining water supply of water supply by i) filtering it Biodegradable waste that has been trapped is decomposed by bacteria present in the forests. E.g. Mangrove roots filter river water of its waste materials before it flows into the sea. The waste is broken down into nutrients for the mangroves.
b) maintains the quality1. Maintaining water supply of water supply through ii) intercepting foliage 1. The foliage of the forest intercepts and weakens the impact + Interception slows of raindrops hitting the down surface runoff so ground. less soil particles are 2. Forest soil thus washed into the river, remains porous making the water enough to let water cleaner. seep underground. 3. This water is stored as groundwater, which flows to and replenishes nearby rivers and reservoirs.
Textbook p. 182 Foliage interception slows down surface runoff.Less soil particles get washed into the river Rainwater seeping into the Water that finally gets to the river soil is cleaner. is filtered by the soil.
How does the water quality inforested areas compare with urban areas, like.... Singapore, Rio de Janeiro, London, Shanghai, Johannesburg, Cairo?
Textbook p. 182 Concrete surfaces means thatrainfall runs over the ground quickly + collects impurities along the way
2. Replenishes O2, removes CO2 Forests: Green Lungs of the Earth During photosynthesis, the greenhouse gas CO2 is absorbed, preventing global temperatures from rising. O2 is released, renewing oxygen supply for all life.
3. Maintains nutrients in the soil 4. Plants absorb1. Dead plant these nutrients inand animal the soil.matteraccumulate onthe forest floor. 3. Calcium, nitrates and phosphates are2. Decomposers released from deadcause dead matter into the soilmatter to rot.
4. Prevents floods Forest roots hold the soil firmly together. This: a) keeps the soil porous as a store for rainwater flowing over the ground b) prevents soil from being eroded and deposited in riverbeds, reducing their capacity to contain water.
5. Protects coasts Mangroves form the first line of defense against wave attack and coastal hazards. E.g. Sri Lanka, 2004 Boxing Day tsunami - Only 2 deaths in a village with densely growing mangroves; up to 6000 deaths in a nearby village with no mangroves (BBC News)
6. Habitat for life Forests are habitats for flora (plants) and fauna (animals), providing Food Shelter from heat or cold Protection from predatorsMatschies tree-kangaroo, Papua (Unfortunately, some areNew Guineas tropical rainforests endangered, e.g. Matschies tree-kangaroo and all species of tigers)American pika, temperate Tigers, tropical rainforests andconiferous forests monsoon forests
7. Provides valuable resources Valuable resources include timber for furniture and buildings. Teak, meranti, rattan (tropical rainforest); mahogany, pine, spruce (temperate coniferous forests) United Nations Food and Agriculture Organization (FAO) estimate that every year, the global timber industry earns over S$332 billion!
7. Provides valuable resources Valuable resources include medicine. Quinine, treatment for malaria, from Cinchona trees (tropical rainforest) Tannin from mangrove Rhizophora and redwood trees (coniferous forests) to make anti- diarrhea pills
7. Provides valuable resources Valuable resources include chemicals. Pine and fir resin as wood varnish Tannin from mangrove Rhizophora and redwoods to treat leather and make orange food dyes
8. Recreation Forests can be used for ecotourism. Tourists who want to experience nature without harming it.Yosemite National Park, California These forests are USA sometimes national parks and wildlife reserves. More of this when we study deforestation in Kalimantan.Sungei Buloh WetlandReserve, Singapore
Functions/Uses of the forest1. Maintains water supply 6.Habitat for life2. Replenishes oxygen, 7. Provides timber, fuel, removes carbon dioxide medicine, food, chemicals3. Maintains nutrients in the soil 8. Recreation4. Prevent floods 9. Research and education5. Protect coasts
Whats next?We will study the final section for this topic: What happens when humans interact with the forest?Well study deforestation (the destruction of tropical rainforests) in Kalimantan, Indonesia. Read textbook pp. 196-201.