Photosynthetic responses of Douglas-fir seedlings to CO{sub 2} at two soil temperatures
- Oregon State Univ., Corvallis, OR (United States); and others
Plant responses to increasing CO{sub 2} can be modified by soil temperatures which change over the growing season and a increase with global change. We used controlled environment experiments with an economically and ecologically important species, Pseudotsuga menziesii (Douglas-fir) to test this idea. Douglas-fir seedling were grown from seeds for 6 months in controlled-environment chambers at two levels of CO{sub 2} (350 and 700 PPM) and at two soil temperatures (13{degrees} and 17{degrees}C). Seedlings were grown in soils collected from the Andrews Experimental Forest within the native range of Douglas-fir. Steady state gas exchange equipment, matched to chamber conditions, was used to assess the response of carbon assimilation rates to intercellular CO{sub 2} concentrations, air temperatures, and photosynthetic photon flux density. Elevated CO{sub 2} reduced carboxylation efficiency, maximum photosynthetic capacity, and quantum yield. In addition, trees grown at high soil temperatures and at low CO{sub 2} had higher photosynthesis across all temperatures ranging from 10{sup {degrees}} to 20{degrees} C. These results show that photosynthetic characteristics of Douglas-fir are affected by both CO{sub 2} and soil temperature, and that as soil temperatures warm seasonally or over the long-term photosynthesis will increase both at ambient and elevated CO{sub 2} until constrained by other factors.
- OSTI ID:
- 107095
- Report Number(s):
- CONF-9507129--
- Journal Information:
- Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 3 Vol. 76; ISSN BECLAG; ISSN 0012-9623
- Country of Publication:
- United States
- Language:
- English
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