MODELLING CANOPY PHOTOSYNTHESIS FOR TWO GRASSLAND COMPETING SPECIES

摘要

A modelling approach have been used to investigate two competing species in grassland areas in the Southern Andes of Ecuador. In this approach a land surface model framework has been used, which includes evaluation of the radiation transfer, the biochemistry of photosynthesis and the plant rooting systems. For a proper parameterization of new average individuals, field and laboratory measurements have been undertaken, in which two photosynthetic pathways are considered, the C3 bracken fern and the C4 Setaria pasture grass. In addition shade acclimation is considered by duplicating measurements on shade and sunlit leaves. As a result, canopy net assimilation and potential primary productivity could be simulated for these two competing species in a very good agreement with measurements and literature data. It is shown that the exotic pasture grass is still competitive, despite contrary field observations. Most of land surface models has the same implementation being investigated here, which makes insights of a detailed one-dimensional approach valuable and easy extendable to a spatial explicit model.