Long-term response of Sitka spruce (Picea sitchensis (Bong.) Carr.) to CO2 enrichment and nitrogen supply. I. Growth,biomass allocation and physiology |
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Authors: | Shi-Rong Liu Craig Barton Helen Lee Paul G. Jarvis Dave Durrant |
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Affiliation: | 1. Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry , Beijing, 100091, China;2. Institute of Ecology and Resource Management, University of Edinburgh , King's Buildings, Darwin Building, Mayfield Road, Edinburgh, EH9 3JU, UK;3. Forestry Research Station, Forestry commission , Alice Holt Lodge, UK |
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Abstract: | ABSTRACT After a 3-year exposure to elevated CO2, young trees of Sitka spruce (Picea sitchensis (Bong.) Carr.) were planted in native, nutrient-deficient forest soil and grown for two more years with three CO2 treatments in open-top chambers, and with two nutrient treatments (with and without supplied N). Elevated CO2 resulted in larger fresh mass, dry mass, leaf area and leaf thickness in two-year old needles, but had no effect on one-year old and current needles. Tree height, basal diameter and biomass production also increased, regardless of N supply. In trees without added N, elevated CO2 resulted in higher root-to-shoot and absorbing roots-to-stump ratios. Regardless of N supply, trees grown in elevated CO2 had lower photosynthetic rates on a leaf area basis. Photosynthesis reduction was accompanied by a decline in Rubisco activity and leaf N concentration. Under elevated CO2, added N elevated photosynthesis and Rubisco activity, suggesting a dependence on N availability of the photosynthetic response to elevated CO2. Stomatal conductance of trees grown with added N decreased in response to elevated CO2. This may account for the larger reduction in intercellular CO2 concentration, and hence photosynthesis, in the trees supplied with N than in those without N supply. |
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Keywords: | growth carbon and nitrogen allocations CO2 enrichment nitrogen supply Sitka spruce |
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