MODELLING CANOPY PHOTOSYNTHESIS FOR TWO GRASSLAND COMPETING SPECIES

摘要

A modelling approach have been used to investigate tworncompeting species in grassland areas in the SouthernrnAndes of Ecuador. In this approach a land surfacernmodel framework has been used, which includesrnevaluation of the radiation transfer, the biochemistry ofrnphotosynthesis and the plant rooting systems. For arnproper parameterization of new average individuals,rnfield and laboratory measurements have beenrnundertaken, in which two photosynthetic pathways arernconsidered, the C3 bracken fern and the C4 Setariarnpasture grass. In addition shade acclimation isrnconsidered by duplicating measurements on shade andrnsunlit leaves. As a result, canopy net assimilation andrnpotential primary productivity could be simulated forrnthese two competing species in a very good agreementrnwith measurements and literature data. It is shown thatrnthe exotic pasture grass is still competitive, despiterncontrary field observations. Most of land surface modelsrnhas the same implementation being investigated here,rnwhich makes insights of a detailed one-dimensionalrnapproach valuable and easy extendable to a spatialrnexplicit model.