The linear relation between stand yield and integrated light in a shade-adapted annual grass'

BARDEN, L. S. (Department of Biology, University of North Carolina at Charlotte, Charlotte, NC 28223). The linear relation between stand yield and integrated light in a shade-adapted annual grass. Bull. Torrey Bot. Club 123: 122-125. 1996.-Many ecology textbooks state that the photosynthetic response of plants to varying light is represented by the response of single leaves, which is a downward concave curve that often reaches saturation. Single leaves of the shade-adapted, annual grass, Microstegium vimineum (Trinius) A. Camus, saturate at 25% full sunlight. However, two field experiments showed that stand dry weight yield at the end of the growing season was a linear function of integrated light, rather than a downward concave saturation-type curve. The linear relation for M. vimineum stands concurs with results of several agricultural studies and may have implications for forest growth models that assume saturation-type response curves for whole trees or forest canopies.