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(Upload on September 20 2015) [ 日本語 | English ]

Topics of revegetation on Mount Usu






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

[ volcanoes | volcanology | Mount Usu ]

Table 1. Life form and seed dispersal type of vascular plants observed on the volcano Usu (number of species). I: Vegetatively recovering species, II: Immigrant species, III: Artificially introduced species, and IV: Buried-seed species (Tsuyuzaki 1987)
GroupIIIIIIIVTotal
Annual030811
Perennial6483984
Woody3172040
Wind-dispersed
___long distance7100017
___short distance4934763
Gravity-dispersal1010516
Self-dispersal820515
Animal-dispersal2121024
Total9518517135
Summit area before the 1977-78 eruptions

Forests dominated by Populus maximowiczii and Betula platyphylla var. japonica
Artificial meadows: grazed by cow

The effects of the 1977-78 eruptions

The summit area was covered with volcanic ejecta of which thickness was 1-3 m
→ the former vegetation was completely destroyed
After the eruptions, I have annually monitored vegetation succession on the summit areas, by using permanent plots, since 1983. The survey in 2015 was completed.

plant community dynamics on volcanoes

Characteristics of succession after the 1977-78 eruptions (特徴)


Permanent pltos monitored for more than 30 years confirmed the following four topics

Usu

  1. A rolling stone gathers no moss
    No moss stage in the succession (Tsuyuzaki 1987)
  2. You can't squeeze blood out of stone
    No annual plant stage in the succession (Tsuyuzaki 1994)

    ⇒ Exception: seedbank (埋土種子) in the former topsoil contained many annuals

  3. Unsung heroes in the plant community
    Perennial plants derived from vegetative reproduction were dominated soon after the eruption (Tsuyuzaki 1989)
  4. Fable of the hare and the tortoise
    Forestation was faster on slowly-recovered areas in the early stages than on areas recovered fast (Tsuyuzaki 2009)
    See the abstract of G8 symposium P
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