Carbon Budgets of Quercus Rubra L. Seedlings at Selected Stages of Growth: Influence of Light

摘要

To determine potential growth responses of northern red oak (Quercus rubra L.) seedlings to various field light environments, carbon budgets of one-, two-, and three-flush seedlings were calculated. Leaf carbon dioxide exchange rate (CER), root respiration, and growth analysis provided inputs for the budgets. Daily CO sub 2 assimilation rates obtained from these budgets were lower than, but consistent with, actual red oak seedling growth rates. The budgets predicted that optimum daily CO sub 2 assimilation occurs under saturating irradiances in the absence of other stresses (e.g., drought), and that daily CO sub 2 assimilation is inadequate to match seedling respiration under the shade of a typical closed forest canopy. Calculated minimum incident photosynthetic photon flux densities required for sufficient CER to balance daily seedling respiration ranged from 30 to 150 mu mol photons m sup -2 s sup -1 , depending on plant size. 44 refs., 7 tabs. (ERA citation 12:013359)