The impact of elevated [CO2] and temperature in boreal Norway spruce forest

• This presentation is based on two experiments where whole-tree chambers (WTC) were used to expose 40-year-old field-grown Norway spruce trees at Flakaliden research site in northern Sweden to elevated [CO2], 700 mol CO2 mol-1, in combination with fertilisation (exp 1) and elevated air temperature (exp 2) aiming to simulate a likely climate in year 2100. Impacts are determined on net CO2 exchange on current and 1-year-old shoots and on biomass of shoot and tree levels. Elevated air temperature had a prominent influence on the timing of photosynthetic spring recovery and depression in autumn resulting in ca 3 weeks longer season of photosynthetic activity, while no effect was observed during the season. Elevated [CO2] had little or no effect on the recovery rate or autumn depression, but light saturated photosynthesis were on average stimulated by ~50% during the seasons. However, the stimulation was positively dependent on both temperature and light intensity in agreement with the prediction by the Farquhar model, resulting in a variable photosynthetic response over the season. Elevated air temperatures resulted in an earlier commencement of bud development and faster shoot elongation, while [CO2] had no effect. Elevated air temperature had no effect on developed shoots while light saturated photosynthesis in elevated [CO2], similar to 1-year old shoots, was stimulated by ca 50%. The resulted is that current-year shoots will assimilate their own mass in terms of carbon 20-30 days earlier in a future climate compared to the current, and thereby significantly contribute to the canopy assimilation during their first year. Although, both elevated [CO2] and air temperature alone and in combination had positive effects on the annual CO2 assimilation, no effect was observed on stem growth in these treatments except when elevated [CO2] was combined with fertilisation. *The following colleagues should be especially acknowledged for contributions to this presentation: Sune Linder, Marianne Hall, Jane Medhurst, Michelle Slaney, Johan Uddling, Mats Räntfors, Bjarni Sigurdsson and Eric Ceschia

Ämnesord

LANTBRUKSVETENSKAPER  -- Lantbruksvetenskap, skogsbruk och fiske -- Jordbruksvetenskap (hsv//swe)

AGRICULTURAL SCIENCES  -- Agriculture, Forestry and Fisheries -- Agricultural Science (hsv//eng)

NATURVETENSKAP  -- Biologi -- Mikrobiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Microbiology (hsv//eng)

NATURVETENSKAP  -- Biologi -- Botanik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Botany (hsv//eng)

Nyckelord

Carbon dioxide

climate change

whole-tree chambers

photosynthesis

phenology

Picea abies

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