Effect of CO2‐enrichnient on seedling physiology and growth of two tropical tree species

• DOI: 10.1111/j.1399-3054.1985.tb08658.x
• Publication Date: 2006-04-30T23:33:02Z
• Authors: Steven F. Oberbauer; Boyd R. Strain; Ned Fetcher
• Keywords: 0106 biological sciences; 15. Life on land; 01 natural sciences

Seedlings of two tree species from the Atlantic lowlands of Costa Rica, Ochroma la‐gopus Swartz, a fast‐growing pioneer species, and Pentaclethra macroloba (Willd.) Kuntze, a slower‐growing climax species, were grown under enriched atmospheric CO2 in controlled environment chambers. Carbon dioxide concentrations were maintained at 350 and 675 μl 1−1 under photosynthetic photon flux densities of 500 μol m−2 s−1 and temperatures of 26°C day and 20°C night. Total biomass of both species increased significantly in the elevated CO2 treatment; the increase in biomass was greatest for the pioneer species, O. lagopus. Both species had greater leaf areas and specific leaf weights with increased atmospheric CO2. However, the ratio of non‐pho‐tosynthetic tissue to leaf area also increased in both species leading to decreased leaf area ratios. Plants of both species grown at 675 μl 1−1 CO2 had lower chlorophyll contents and photosynthesis on a leaf area basis than those grown at 350 μl 1−1. Reductions in net photosynthesis occurred despite increased internal CO2 concentrations in the CO2‐enriched treatment. Stomatal conductances of both species decreased with CO2‐enrichment resulting in significant increases in water use efficiency.