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CABI Book Chapter

Environmental changes and geomorphic hazards in forests.

Book cover for Environmental changes and geomorphic hazards in forests.



Chapter 9 (Page no: 167)

Natural hazards in forests: glacier and permafrost effects as related to climate change.

Atmospheric warming is predicted to be greater in polar regions than at lower latitudes and more pronounced at high altitudes than in lowlands. In polar regions, air and ground warming may lead to a more northerly extension of the boreal forest, as growing seasons lengthen and become warmer. Near-surface permafrost degradation will probably accompany such an evolution in environmental conditions. In some cases slope movement may be catastrophic, but in most instances the settlement is expected to be slow, and the water released by melting ground ice will evaporate. Subpolar forests in permafrost regions are primarily used for firewood and rough lumber, but not construction-grade materials. This is unlikely to change because long-term ground instability, relatively cold soil temperatures, depletion of nutrients in the active layer, and restriction of root systems to the active layer all limit tree growth. Extensive forest fires, usually initiated by lightning after a week or two of hot weather, also deplete timber stocks. There have been suggestions that wildfire may increase following climate warming. Meltwater runoff from glaciated and perennially frozen areas represents only a small portion of the annual water supply, but strongly influences stream flow in lowlands during the warm/dry season. The disappearance of perennial ice above and below the earth surface influences the seasonality of discharge by reducing meltwater production in the warm season and by increasing the permeability of frozen/thawing materials. The latter effect may have strong impacts on soil humidity and growth conditions for forest and tundra in such dry areas as Tian Shan Mountains or Tibet Plateau. In general, accelerated future warming would cause an enlargement of the periglacial belt in high mountain areas, an upslope shifting of hazard processes and a widespread reduction in the stability of formerly glaciated or perennially-frozen slopes. In the case of accelerated future warming, the cryospheric components of high mountain environments would be expected to change at high rates and lead to pronounced disequilibria in the water cycle, in mass-wasting processes and sediment flux, as well as in growth conditions for vegetation. For those directly involved with such changes, the main challenge would be to adapt to the high rates of environment evolution. Empirical knowledge would have to be replaced more and more by improved process understanding, especially concerning runoff formation and slope stability.

Other chapters from this book

Chapter: 1 (Page no: 1) Geomorphologic hazards and forest environmental change - an introduction. Author(s): Sidle, R. C.
Chapter: 2 (Page no: 7) Potential impacts of climate change on streamflow and flooding in snow-dominated forested basins. Author(s): Wigmosta, M. S. Leung, L. R.
Chapter: 3 (Page no: 25) Regional hydrologic impacts of climate change. Author(s): Burn, D. H.
Chapter: 4 (Page no: 45) The potential impact of global change on surface erosion from forest lands in Asia. Author(s): Lo, K. F. A. Cai QiangGuo
Chapter: 5 (Page no: 67) Climate change related to erosion and desertification: 1. Mediterranean Europe. Author(s): Rodolfi, G. Zanchi, C.
Chapter: 6 (Page no: 87) Climate change related to erosion and desertification: 2. Africa. Author(s): Beckedahl, H. R.
Chapter: 7 (Page no: 101) The effects of environmental changes on weathering, gravitational rock deformation, and landslides. Author(s): Chigira, M.
Chapter: 8 (Page no: 123) Potential effects of environmental change on landslide hazards in forest environments. Author(s): Sidle, R. C. Dhakal, A. S.
Chapter: 10 (Page no: 203) Global changes, mangrove forests and implications for hazards along continental shorelines. Author(s): Taylor, D. Sanderson, P. G.
Chapter: 11 (Page no: 227) Future directions for geomorphologic hazard analysis in forests. Author(s): Sidle, R. C.

Chapter details

  • Author Affiliation
  • Department of Geography, University of Zurich, Winterthurerstrasse 190 CH-8057, Zurich, Switzerland.
  • Year of Publication
  • 2002
  • ISBN
  • 0851995985
  • Record Number
  • 20023157479