(Upload on March 15 2021) [ 日本語 | English ]

Stress (ストレス)

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

Cannon WB (1871-1945, physiologist)

firstly proposed stress for medical term

Seyle H (1907-1982, endocrinologist)

defined the characteristics
→ a theory of stress (ストレス学説提唱), or general adaptation syndrome (汎適応症候群)

  1. stressor (ストレッサー, ストレス刺激): external-environmental stimuli that induce stresses
    physical stressor: temperature, UV, etc.
    chemical stressor: chemical substance, enzyme, etc.
    biological stressor
  2. stress (ストレス, ストレス反応): responses of plants (and animals) induced by stressors

[ water stress ]

Trade-offs between stress tolerance and competitive ability (Toll 2022)

→ habitat partitioning

Injury response (傷害応答)

Chilling injury (冷害)

any damages to plants caused by temperatures above the freezing point (0°C)

Freezing injury (凍害)

freeze damage occurs during an advection freeze
frost damage occurs during a radiation freeze

these two injuries are closely related

→ the formation of ice crystals in plant tissues, dehydrating cells and disrupting membranes Snow

Snow injury (雪害)

Relationships between broad-leaved trees and coldness
Damages induced by coldness → the migration of broad-leaved trees is limited
  1. Direct effects: Ex. tissue fluid (water) frozen by low temperature → tissue(s) is(are) frozen → freezing injury
  2. Indirect effects: Ex. frost drought (in particular the abovegroud organs)
    bark: vessels are clogged up → inhibition of water transportation + evaporation (on the aboveground) → death owing to dehydration
Difficulties in plant establishment in relation to cold tolerance
  1. unstable climate in early fall
  2. unstable climate in early spring (in particular occurring late frost)
    The frequency of late frosts determines the establihsment of European beech in Europe and Sakhalin fir in Hokkaido

Stress avoidance (ストレス回避)

1. physiological tolerance

seed dormancy

2. morphological tolerance (resistance)