Disturbance

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Disturbance (撹乱)

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

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

Problems

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

Three parameters on disturbances

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)

[ natural disturbance | human disturbance ]

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

Forest fire at Alaska

Sprouting after fire at Boston Creek (May 11 2005)	Moderately disturbed site. Peat moss still remained on the forest floor.	Intensively disturbed site. Peat was completely burned out by fire. Snags could not keep standing (Tsuyuzaki et al. 2014).

Small-scale

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