ANOXIA TOLERANCE IN HIGH ARCTIC VEGETATION

A uniquely high level of anoxia tolerance has been observed in Spitsbe rgen populations of some common high arctic vascular plant species. Th e most surprising aspect of anoxia tolerance in these species is their ability to maintain turgid, green leaves throughout the period of ano xia and into the postanoxic recovery phase. Prolonged anoxia tolerance has never been reported previously for green leaves, which normally l ose turgor and wither rapidly when deprived of oxygen. Tests on more s outhern populations from Norway, Iceland, and Scotland of species foun d to be tolerant of anoxia in Spitsbergen failed to detect an equivale nt ability to survive oxygen deprivation. This distinctive feature of high arctic populations as compared to more southern populations of th e same species suggests a different evolutionary history for arctic po pulations as compared with those from lower latitudes. Possession of a such an unusual physiological feature whole-plant anoxia tolerance, n ot found in more southerly populations, is an additional argument for suggesting that some arctic populations of vascular plants may have su rvived part of the Pleistocene epoch at high latitudes in ice-free pol ar deserts. Such populations will have been exposed to many climatic a lterations in the past and this history of a long-term presence in the High Arctic is discussed in relation to current threats to arctic veg etation from climatic warming.