ibclogo XVI International Botanical Congess

Abstract Number: 4769
Poster No. = 1390


EFFECTS OF RISING ATMOSHPHERIC CO2 CONCENTRATION ON GROWTH AND PHYSIOLOGYOF SITKA SPRUCE


Shirong Liu1, Craig Barton2, Helen Lee2, Paul G Jarvis2 and Dave Durrant3, 1Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing 100091, PR. China. 2Institute of Ecology and Resource Management, University of Edinburgh, King's Buildings, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, UK. 3Forestry Research Station, Forestry commission, Alice Holt Lodge,UK.


After continuous exposure for three years to elevated CO2 in pots, young trees of Sitka spruce (Pieca sitchensis (Bong.) Carr.) were planted out in a native, nutrient-deficient forest soil and grown for two more years in three CO2 treatments (ca 700 ?mol mol-1, ambient CO2 in open-top chambers (OTCs) and ambient CO2 outside), with two nutrient treatments. Elevated CO2 significantly increased tree height, basal diameter and biomass production, regardless of added N supply. There were no effects of elevated CO2 on biomass allocation, but some morphological modifications occurred under elevated CO2. Trees without added N supply had slightly higher ratios of root:shoot and absorbing roots to stump in response to elevated CO2. Regardless of added N supply, trees grown in elevated CO2 had lower photosynthetic rates on a leaf area basis than those grown in ambient CO2either in OTCs or outside. Reduction in photosynthesis was accompanied by decline in Rubisco activity and leaf N concentration. Stomatal conductance of trees with added N supply decreased in response to elevated CO2.

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