Hedda Bakåsmoen HOLM, University of Bergen, Norway
Benjamin Aubrey ROBSON, University of Bergen, Norway
Ole Reidar VETAAS, University of Bergen, Norway
Hutchinson's niche model will predict that species must migrate in space to remain inside their climatic niche in case of climate change. We examined whether the main population of Artemisia norvegica (Fr.) (at Dovre) has had an upward range shift in the past 90 years and if a subpopulation of A. norvegica on Mt Vassli (Hardanger) is becoming locally mountain-top extinct. Two hypotheses were tested: direct warming-induced extinction and/or upward displacement of Betula pubescence, which may outcompete A. norvegica for light. In addition, we assessed if elevation-dependent warming (EDW), i.e. faster warming at higher elevations than lowlands, has lowered the lapse rate throughout the previous three climate normal periods (1931-1960, 1961-1990, 1991-2020).
The temperature optimum of A. norvegica and its tolerance range for the three climatic normal periods and the total were estimated using a generalized linear model on occurrence only data and logistic regression on presence-absence data. The EDW was interpreted from the lapse rates for each normal period. EDW was verified in continental climate but not in the oceanic climate.
In the last 90 years A. norvegica has mowed upwards by 2.5 metres/year. Although the elevation optimum has increased, the temperature optimum had also cooled.
Climate forecasts project a temperature optimum for A. norvegica at a higher location than Mt Vassli. Consequently, there is no land for range shift and the Hardanger subpopulation may go mountain-top extinct. In addition, may the light-demanding alpine plant be may out shadowed and outcompeted by B. pubescence, which is mowing upwards nationwide and locally at Mt Vassli. EDW is predicted to increase the length a species must move to stay within its climate niche during climate change.
Mots clés : biogrography|climate change|alpine|niche|land use
A105298HH