How to protect forest~why we practice thinning~


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I am working in KWS Malindi Marine Park in Kenya, as a volunteer of JICA.
I am teaching environment for children. In this presentation, I will discuss about why we need to practice thinning. Also techniques of thinning tree and products, which timber tips used are discussed in this presentation.

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  • 間伐するとどうなるの? 間伐の種類 切られた木はどうなるの?
  • selective thinning 定性間伐 fixed thinning 定量間伐 row thinning 列状間伐
  • 定性間伐 木々の形質の重点を置いて、あらかじめ伐る木を決めて行う間伐。 基本的には、成長のよくない木、ひょろひょろとした木、曲がった木などから順に伐採し、優良木を残します。 間伐木の選定が大切で、間伐方法の主流。
  • fixed thinning 定量間伐 定量間伐 立木の密度に重点を置いて、残す量をあらかじめ決めて行う間伐
  • 列状間伐 定量間伐の一種で斜面の上下に沿って列状(筋状)に間伐する方法。 列状間伐は「部分皆伐」といわれることもある。 高性能林業機械によって、低コストで効率的に間伐ができる新しい方法。 3列を残して1列を伐採する「3残1伐」や「4残1伐」など、森林の状況により方法を選択。 列状間伐では、定性間伐のように伐採する木を選ばず、効率を優先するため、優良木を伐採したり、不良木が残ってしまうという短所もある。伐採した木の良否によって、使い道を分けることができれば、合理的な間伐方法になる。
  • 切られた木はどうなるの?
  • How to protect forest~why we practice thinning~

    1. 1. How to protect forest?~Why we practice thinning?~ Takatoshi AKAI KWS Malindi Marine Park 231 JOCV/JICA
    2. 2. Outline• What will be happened after thinning trees?• Types of periodic thinning• What will be happened to cut-downed trees?
    3. 3. Q: Is it good to cut tree?
    4. 4. Thin diameter Without thinning, they Equalized looks like bean diameter sprout 1st 2nd Treethinning thinning Grow Well
    5. 5. Without thinning Thinning treePrecipitation impact Precipitation impact [huge] [little] Gr ou Gr nd ou f lo nd w fl o [m w u ch [lit ] t le] Penetration Penetration [little] [plenty]
    6. 6. Before AfterRetard the growth of each other After thinning trees,by cover up and shut down light. they grow up healthy.Once shut down light, forest Also sunlight grow other plantsbecome dark. to enhanced eco-system in the forest.
    7. 7. Types of periodic thinning
    8. 8. Selective Thinning• Main technique to grow trees.• Focus on shape of each trees.• Then decide which tree cut down.• Such as slow growing tree, spindly tree, bended tree, to remain good tree.
    9. 9. Fixed Thinning• Focus on density of trees.• Then decide which tree cut down on the map, before start to cut trees.
    10. 10. Row Thinning• Cut down trees in line.• Cheapest and efficiently technique.• We can choose depends on the status of forest. “3 remain, 1 thinning”: remain 3 lines and cut down 1 line, or “4 remain, 1 thinning”: remain 4 lines and cut down 1 line.• Weak point: We focused on efficiency and do not choose tree. Therefore, it may be cut down good tree, and remain useless tree
    11. 11. TipsTimber What will be happened to cut-downed trees?• We will use trees for build house and other products• We also use tips of tree for chop sticks or charcoals.
    12. 12. Conclusion• Cutting tree with sustainable development is good activity• Once thinning trees, the remained trees become valuable products.• Thinning also avoid land slide after heavy rain.• Thinned trees are nothing to waste, it able to use for building material, and timber tips also able to use for chopsticks.