Are heat and cold resistance of arctic species affected by successive extreme temperature events?
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.
Marchand
F L
FL
Research Group Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Campus Drie Eiken, Universiteitsplein 1, B-2610 Wilrijk, Belgium.
Kockelbergh
Fred
F
van de Vijver
Bart
B
Beyens
Louis
L
Nijs
I
I
D001110:Arctic Regions; D031255:Carex Plant / Q000254:growth & development / Q000502:physiology; D002734:Chlorophyll / Q000378:metabolism; D003081:Cold Climate; D029791:Ericaceae / Q000254:growth & development / Q000502:physiology; D005453:Fluorescence; D017752:Greenhouse Effect; D006358:Hot Temperature; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000502:physiology; D018515:Plant Leaves / Q000254:growth & development* / Q000502:physiology; D028502:Polygonum / Q000254:growth & development / Q000502:physiology; D032108:Salix / Q000254:growth & development / Q000502:physiology; D013045:Species Specificity
D045332:Photosystem II Protein Complex; D002734:Chlorophyll