|Publication Type:||Journal Article|
|Year of Publication:||2006|
|Authors:||Marchand, F. L., Kockelbergh, F., van de Vijver, B., Beyens, L., Nijs I.|
|Keywords:|| Ecology: environmental biology - General and methods,  Ecology: environmental biology - Plant,  Cyperaceae,  Betulaceae,  Empetraceae,  Ericaceae,  Polygonaceae,  Pyrolaceae,  Salicaceae, Angiospermae, Betula nana: species [Betulaceae], Betulaceae: Angiosperms, Carex bigelowii: species [Cyperaceae], cold resistance, Cyperaceae: Angiosperms, Dicots, Dicotyledones, Empetraceae: Angiosperms, Empetrum nigrum: species [Empetraceae], Environmental Sciences, Ericaceae: Angiosperms, heat resistance, infrared irradiation, Monocots, Monocotyledones, photosynthesis, Plantae, Plants, Polygonaceae: Angiosperms, Polygonum viviparum: species [Polygonaceae], Pyrola grandiflora: species [Pyrolaceae], Pyrolaceae: Angiosperms, Salicaceae: Angiosperms, Salix arctica: species [Salicaceae], Spermatophyta, Spermatophytes, successive extreme temperature events, Terrestrial Ecology: Ecology, Vaccinium uliginosum: species [Ericaceae], Vascular plants, vulnerable tundra vegetation|
Extreme temperature events are projected to increase in frequency in a future climate. As successive extremes could occur more frequently, patches of vulnerable tundra vegetation were exposed to two consecutive heat waves (HWs) of 10 d each, with a 5-d recovery period in between.Surface temperatures during the HWs were increased approximately 6 degrees C using infrared irradiation sources.In three of the four target species (Pyrola grandiflora, Polygonum viviparum and Carex bigelowii), plant conditions improved upon the first exposure. Depending on species, leaf relative growth, leaf chlorophyll content or maximal photochemical efficiency was increased. In P. grandiflora the positive effects of the heat on the photosynthetic apparatus led to augmented net photosynthesis. By contrast, Salix arctica responded mainly negatively, indicating species-specific responses.During the second HW, leaf mortality suddenly increased, indicating that the heat stress induced by the extreme events lasted too long and negatively influenced the species resistance to high temperature. After the HWs, when plants were exposed to (low) ambient temperatures again, plant performance deteriorated further, indicating possible loss of cold resistance.