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Margareta Johansson

Forskare

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Effects on the structure of arctic ecosystems in the short- and long-term perspectives

Författare

  • Terry V. Callaghan
  • Lars Olof Björn
  • Yuri Chernov
  • Terry Chapin
  • Torben Christensen
  • Brian Huntley
  • Rolf A. Ims
  • Margareta Johansson
  • Dyanna Jolly
  • Sven Jonasson
  • Nadya Matveyeva
  • Nicolai Panikov
  • Walter Oechel
  • Gus Shaver
  • Heikki Henttonen
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Summary, in English

Species individualistic responses to warming and increased UV-B radiation are moderated by the responses of neighbors within communities, and trophic interactions within ecosystems. All of these responses lead to changes in ecosystem structure. Experimental manipulation of environmental factors expected to change at high latitudes showed that summer warming of tundra vegetation has generally led to smaller changes than fertilizer addition. Some of the factors manipulated have strong effects on the structure of Arctic ecosystems but the effects vary regionally, with the greatest response of plant and invertebrate communities being observed at the coldest locations. Arctic invertebrate communities are very likely to respond rapidly to warming whereas microbial biomass and nutrient stocks are more stable. Experimentally enhanced UV-B radiation altered the community composition of gram-negative bacteria and fungi, but not that of plants. Increased plant productivity due to warmer summers may dominate food-web dynamics. Trophic interactions of tundra and sub-Arctic forest plant-based food webs are centered on a few dominant animal species which often have cyclic population fluctuations that lead to extremely high peak abundances in some years. Population cycles of small rodents and insect defoliators such as the autumn moth affect the structure and diversity of tundra and forest-tundra vegetation and the viability of a number of specialist predators and parasites. Ice crusting in warmer winters is likely to reduce the accessibility of plant food to lemmings, while deep snow may protect them from snow-surface predators. In Fennoscandia, there is evidence already for a pronounced shift in small rodent community structure and dynamics that have resulted in a decline of predators that specialize in feeding on small rodents. Climate is also likely to alter the role of insect pests in the birch forest system: warmer winters may increase survival of eggs and expand the range of the insects. Insects that harass reindeer in the summer are also likely to become more widespread, abundant and active during warmer summers while refuges for reindeer/caribou on glaciers and late snow patches will probably disappear.

Avdelning/ar

  • Molekylär cellbiologi
  • Institutionen för naturgeografi och ekosystemvetenskap

Publiceringsår

2004

Språk

Engelska

Sidor

436-447

Publikation/Tidskrift/Serie

Ambio: a Journal of Human Environment

Volym

33

Issue

7

Dokumenttyp

Artikel i tidskrift

Förlag

Springer

Ämne

  • Physical Geography
  • Biological Sciences

Nyckelord

  • terrestrial ecosystems climate change ultraviolet radiation

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0044-7447