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Disturbance (撹乱)






Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

Major catastrophic events originating in the physical environment - events which cause abrupt structural change in communities (White 1979)

☛ disaster (災害)

Problems

  1. There is a gradient from minor to major events rather than a uniquely definable set of major catastrophes for each kind of disturbance
  2. Some disturbances are initiated or promoted by the biotic component of the system

Three parameters on disturbances

3D-disturbacne
Disturbance regime = determined by the type and three parameters to characterize disturbances shown below:

Scale (size)
Frequency (interval)
Intensity (magnitude)

→ Grime's triangle → succession (遷移)
索引

Type

• Natural disturbance
• Human disturbance (human-induced disturbance, or anthropogenic disturbance)

Ecosystem health (生態系の健全性)

a metaphor used to describe the condition of an ecosystem

productivity resilience, and organization, including biodiversity

changed by disturbances, e.g., flooding, drought, biological invasion, climate change, mining, overexploitation, and landuse change
⇒ the relationship between resilience and diversity

Natural disturbance (自然撹乱)

Volcanic eruption
Landslide
Wildfire

black spruce forests in Alaska (Tsuyuzaki et al. 2014)
Sprouting Moderately-disturbed Intensitvely-disturbed

Table. Roles of duff on vegetation dynamics after fire (Johnson 1992)
Fire intensity         Low     High 
Duff consumption
Plant mortalitya     Low     High 
Seed banka           Rich    Poor 
Seedbed               Bad     Well 
a: not only aboveground biomass but also underground biomass, including roots and buried seeds are killed.
Charcoal (used for reconstructing wildfire history)
Ash/charcoal layer - praticle size

[ flood disaster ( 水害 )]

Floodplain (氾濫原)

Pattern of vegetation zonantion on Sorachi River floodplain
floodplain

(Niiyama 1990)

Disturbacnes, such as flood, are important for the vegetation zonation

Human activities destroy the zonation: dam construction + global warming

Human disturbance (人為撹乱)

Large-scale

| Global warming (+ ozene hole)
| ___Environmental hormone
| Desertification → Deforestation
| Acid rain → forest ecosystem change
| Mining, e.g., coal, bauxite, and peat (Nishimura et al. 2009)
| Heat island → urban ecosystem change
| Forest cutting, including skislope establishment (Tsuyuzaki 1994)
| Reclamation for cultivation, such as meadow and paddy
| ___field (Tsuyuzaki & Kanda 1996)
| Grazing by cattle, e.g., yak (Tsuyuzaki & Tsujii 1999),
| ___and deer (Tsuyuzaki & Takahashi 2007)
| Trampling
| Clipping

Small-scale
 [ occurring with various scales = biological invasion (生物学的侵入)]

Trampling (踏圧)

Way to go
  • GSES
    July 29 2019
  • GSES
    August 17 2019
  • GSES
    August 30 2019
  • GSES
    October 7 2019
  • GSES
    November 7 2019
  • GSES
    November 27 2019
  • GSES
    February 18 2019
  • GSES
    February 13 2020
  • GSES
    March 31 2020
  • GSES
    April 6 2020
  • GSES
    May 8 2020
  • GSES
    May 25 2020
  • GSES
    October 26 2020
  • GSES
    March 16 2023
  • GSES
    August 19 2023
  • GSES
    October 28 2023
Directly affecting vegetation
Shoot damages
Reduced plant activities
Reduced regeneration
Lost vegetation cover
Lost diversity
Indirectly affecting vegetation via the alteration of soil
Lost organic matter
Reduced soil porosity
Decreased air and water permeability
Increased run off
Increased soil instabilities
☛ the effects of yak grazing on vegetation

= grazing + trampling (+ human impact)

☛ camp site (Tsuyuzaki & Titus 2010)

Extreme environment (極限環境)

environments that are considered hard to survive in due to its extreme conditions such as temperature, accessibility to different energy sources or under high pressure

Alpine (高山)

Alpine zone (高山帯)
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