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The Arctic is an Ecosystem
by Bill Heal
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The Terrestial Ecosystem Or Ecosystems
The future for terriestial ecosystems
  Predicting changes over the next 50-100 years is difficult! It is not only the changes in the balance of production and decomposition within the system that have to be considered. It is also the rate of spread of vegetation following the gradual changes in climate. This is where the computer models come into play. The most recent model summarises the climatic factors driving change, and the responses of plant growth and soil organic matter. It is expected that the mean annual temperature of the region will rise by about 4°C this century, more in the High Arctic, less in the subArctic and Boreal forest. Snow and rain will change much less, probably increasing by only a few centimetres each decade. Based on these assumptions, the model is then run from 1850 to 2100, covering the circumpolar region from 50o Northwards. It predicts that:
  • Coniferous forest will expand at the expense of tundra.
  • The present tundra area will be halved by 2100.
  • The increased growth of forest will exceed increased decomposition so that the region will continue to be a carbon 'sink' throughout this Century.
  Many factors have to be taken into account and such models are always tentative. Changes will not be smooth and regular. There will be periods and places where the trend is briefly (decades) reversed because of local conditions and variations in the climate. Short-term changes will be difficult to detect, partly because the biological response will lag behind the climate trend - but the system will change, that is sure.
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The Arctic is an Ecosystem, by Bill Heal.
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