SHOOT STRUCTURE, LEAF PHYSIOLOGY, AND DAILY CARBON GAIN OF PLANT SPECIES IN A TALLGRASS MEADOW

Abstract

We analyzed the importance of shoot structural and leaf physiological characteristics in determining interspecific differences in whole-shoot carbon gain in a tallgrass meadow. Canopy structure, aboveground mass, leaf nitrogen content, and leaf photosynthesis were determined for individual shoots of the dominant grass Miscanthus sinensis (a C4 species) and for four forb species (all C3). These data were used to calculate net daily carbon gain of individual shoots in absolute terms, per unit leaf area, and per unit aboveground biomass (Pmass). Pmass in turn, is an important component of growth per unit mass (relative growth rate, RGR). Miscanthus shoots had a higher total carbon gain and a higher Pmass than shoots of the other species. The greater Pmass of Miscanthus shoots was not because they captured more light per unit mass (Φmass), but because they achieved higher rates of photosynthesis per unit of absorbed light (Plight; Pmass = Φmass × Plight). The latter was mainly due to the higher leaf photosynt...