"What will determine the location of the Arctic treeline in 2100, and what will its location mean for humans?"


Workshop Purpose

The location of the treeline is determined by several factors, including climate, topography, soil characteristics, biological interactions such as grazing, and human pressure such as farming or logging. In Norway, mountain birch forms the treeline, which has been moving northward and upward because of both climate change and reduced grazing. The latter change is the result of changes in Norwegian society that have led to reduced outfarming in mountain regions. Traditional use of the treeline ecosystem, for example by Saami reindeer herders, may also change and affect the treeline. Tourism, in particular the construction of vacation cottages, is increasing in this region. These visitors may harvest trees for firewood. More tourists may lead to more ski areas and ski lifts, which cause considerable ecological damage. Hydroelectric dams have caused significant landscape and aquatic changes in Norway, influencing human settlements and in some cases stopping reindeer migration routes and reducing grazing resources. Reindeer are also affected by roads and railways, and the reindeer population overall is affected by many social, economic, political, and cultural factors.

In short, the location of the treeline is a complex question involving numerous physical, biological, and social phenomena, each of which is in turn affected by many factors. Predicting the location of the treeline in 2100 may be difficult or impossible, but assessing the relative effects of various forces may help us understand the dynamics of the system, which in turn can lead to more effective management and perhaps sustainable utilization of the ecosystem.

Achieving this goal also requires understanding how the treeline affects humans.

Discussion Outline

The questions framed in the discussion forum are:

  • What are the factors influencing the position of northern treeline?
  • How does treeline influence people?
  • How do people influence treeline?
  • How do social, economic, and cultural influences affect the human-treeline relationship?
  • What will treeline look like in 100 years?

"The major thrusts of the HARC initiative are to broaden our understanding of the arctic system and to assist arctic peoples to understand and respond to the effects of large-scale chagnes. HARC is also concerned with the effects of change in the arctic system on people who live outside the Arctic."
–People and the Arctic: A Prospectus for Research on the Human Dimensions of the Arctic System.


Suggested Readings

Barber, Valerie A., Glenn Patrick Juday, and Bruce P. Finney. 2000. Reduced growth of Alaskan white spruce in the twentieth century from temperature-induced drought stress. Nature 405: 668-673.

Briffa, K.R. et al.1998. Reduced sensitivity of recent tree-growth to temperature at high northern latitudes. Nature 391: 678-682.

Garfinkle, H.L. and L.B. Brubaker. 1980. Modern climate–tree-growth relationships and climatic reconstruction in sub-Arctic Alaska. Nature 286: 872-874.

Jacoby, G.C. adn R.D. D'Arrigo. 1995. Tree-ring and width and density evidence of climatic and postential forest change in Alaska. Global Biogeochemical Cycles. 9(2) 227-234.

Sustainable development in northern timberline forests. 1999. Proceedings of the Timberline workshop, May 10-11, 1998, Whitehorse, Canada. Sakari Kankaanpää, Tapani Tasanen, and Marja-Liisa Sutinen (eds.). Finnish Forest Research Institute. Ministry of the Environment of Finland.

Viereck, L.A. 1979. Characteristics of treeline plant communities in Alaska. Holarctic Ecology. 2(4): 228-238.

Nordic Mountain Birch Ecosystems. 2001. Wielgolaski, F.E., ed. Man and the Biosphere Series Volume 27. The Parthenon Publishing Group. Paris, New York, London.