Day 5: Ecosystems and ecosystem services

2024-07-02

Midterm test

  • 30 minutes long

  • 5 minute break after test

  • You may answer in English or Japanese

What are ecosystems?

  • Networks of interacting organisms
  • 「生態系」とは、相互作用する生物のネットワーク

Food web

https://www.nature.com/scitable/knowledge/library/food-web-concept-and-applications-84077181/

The composition of ecosystems differs across the globe

生態系は場所によって構造が違う。

From a conservation standpoint we need to save each one

保全的な観点からすると、それぞれ保全すべき価値がある

Ecosystems are not static

  • Ecosystems change (succession) 生態系は変わることがある（遷移）

Primary succession: when an ecosystem develops from bare rock

一次遷移：溶岩台地などの土壌もない裸地や新しい湖沼などから始まる遷移

Picture of primary succession

https://news.uchicago.edu/explainer/what-is-ecological-succession https://www.shinrin-ringyou.com/shinrin_seitai/seni.php

Secondary succession: when an ecosystem develops after major disturbance

二次遷移：大きな撹乱が起こった後の遷移

Picture of secondary succession

https://news.uchicago.edu/explainer/what-is-ecological-succession

Activity: Which is more diverse?

Which is more diverse: forest with no disturbance or small amount of disturbance

Intermediate disturbance hypothesis

Ecosystems reach highest diversity at intermediate levels of disturbance
中ぐらいの撹乱で種数が最も多くなる（仮定）

Intermediate disturbance curve

https://stephenthomforde.com/intermediate-disturbance-hypothesis-idh/

Disturbance is natural

  • When humans suppress natural change, it lowers biodiversity

  • 撹乱は自然現象である

  • 人間が自然に起こる撹乱を抑えると、生物多様性が低下する

Japan has diverse ecosystems

Brazil 2022, Japan: The Natural History of an Asian Archipelago

Japan has diverse ecosystems

Brazil 2022, Japan: The Natural History of an Asian Archipelago

Ecosystems are linked to ecosystem services （生態系サービス）

Healthy ecosystems have benefits for people

健康的な状態を保った生態系は人間にとって有利

  • Direct　直接的
    • Example: food from plants
  • Indirect　間接的
    • Example: mangroves prevent coastal erosion
  • Aesthetic/ethical　美的・倫理的
    • Example: trees in parks relieve daily stress

Activity: Discuss ecosystem services

  1. List as many ecosystem services as you can in your group (at least 10)

  2. Arrange them in the Venn diagram. Put a star next to ecosystem services that you experience yourself.

  3. Share your results with the class. What are services that show up in multiple categories?

Example to satoyama: Misato, Kumamoto

久保田康裕・生物多様性研究室シンクネイチャー

Satoyama with labels

Satoyama are complex ecosystems with human interactions

里山は人間との相互作用による複雑な生態系

Not one ecosystem, but many

“Traditional, rural landscapes, which are social and ecological networks of a village and its surroundings, which include agricultural lands, open forest lands and forests, and which have maintained a high diversity of plants, insects, and small-to-medium-sized animals”

Fukamachi (2001, Landsc. Ecol. 16: 703–717)

Satoyama are widely distributed throughout Japan

里山は日本全国に広く分布している

https://www.biodic.go.jp/biodiversity/

In satoyama, humans benefit from the ecosystem and help maintain biodiversity

里山では、人間をが生物多様性を維持すると同時に恩恵を受ける

  • Cutting trees prevents any one species from becoming dominant 樹木を伐採することで、種のどれか一つだけが圧倒的に多くなることを防ぐ
  • Watering of rice paddies provides habitat for wetland species 水田への散水は湿地生物に生息地を提供する

Satoyama are being lost due to population shrinkage

人口減少で失われつつある里山

  • The current population of Japan is shrinking 現在の日本の人口は減少している
  • Most young people are in the cities 若者の多くは都会にいる
  • There are fewer and fewer people to manage satoyama, so biodiversity is being lost 里山を管理する人が少なくなり、生物多様性が失われている

The Japanese government is trying to conserve satoyama

日本政府は里山の保全に取り組んでいる

https://www.env.go.jp/nature/satoyama/En_ActionPlan_summary_ver.pdf

Reminder: Quiz next week

Watch the videos and be ready for a quiz next week (7/9)