International Tundra Experiment ITEX 1990 wwwsystbotguseresearchitexitex html

In 1990, the International Tundra Experiment (ITEX) was established as a MAB-NSN (Man and Biosphere; Northern Sciences Network) initiative. Since then the program has grown rapidly, and is today one of the most active international field programs in Arctic ecology. The purpose of ITEX is to monitor the performance of plant species and communities on a circumpolar basis in undisturbed habitats with and without environmental manipulations. At present, there are over 20 active ITEX field sites throughout the eight Arctic countries and in addition some alpine areas (Japan and Switzerland).

The basic experiment is a temperature enhancement manipulation, where the field mean surface temperature is increased by 2-3°C to simulate the climate at the middle of the next century according to the forecast from the general circulation models (GCMs). Most of the results generated within ITEX so far relate to the response of single species, but from the field season of 1995 the experimentation was scaled up to include community-level responses. There are also ITEX research efforts dealing with plant phenotypic plasticity and quantitative genetics of some of the target species.

The results to date can be summarized as follows. The performance of nearly all study species in a warmer climate increases. Different groups of plant species respond in different ways to warming, thereby resulting in changes of community composition. Recruitment of new plant individuals is extremely slow in undisturbed tundra (except perhaps in the polar deserts of the High Arctic); instead we see a loss of species and biodiversity as long as the warming trend persists. Long-term monitoring of manipulated and unmanipulated plots in Arctic Alaska and Subarctic Sweden corroborate the adequacy of these first ITEX results. Thus, we expect a disintegration of the plant communities in the tundra that we are familiar with today, and this must entail drastic changes also for animal populations at the landscape scale.

A volume containing the first set of ITEX-generat-ed papers on vascular plants, presented at the 1995 ITEX workshop at Ottawa, Canada, appeared in print in 1997 as a special issue of Global Change Biology (Volume 3, Suppl. 1). A meta-analysis of lichen responses to warming in ITEX and pre-ITEX experiments was published by Cornelissen et al. (2001).

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