IPR 1.0: an efficient method for calculating solar radiation absorbed by individual plants in sparse heterogeneous woody plant communities

摘要

Climate change may alter the spatial distribution, composition, structureand functions of plant communities. Transitional zones between biomes, orecotones, are particularly sensitive to climate change. Ecotones are usuallyheterogeneous with sparse trees. The dynamics of ecotones are mainlydetermined by the growth and competition of individual plants in thecommunities. Therefore it is necessary to calculate the solar radiation absorbedby individual plants in order to understand and predict their responses toclimate change. In this study, we developed an individual plant radiationmodel, IPR (version 1.0), to calculate solar radiation absorbed byindividual plants in sparse heterogeneous woody plant communities. The modelis developed based on geometrical optical relationships assuming that crowns ofwoody plants are rectangular boxes with uniform leaf area density. The modelcalculates the fractions of sunlit and shaded leaf classes and the solarradiation absorbed by each class, including direct radiation from the sun,diffuse radiation from the sky, and scattered radiation from the plantcommunity. The solar radiation received on the ground is also calculated. Wetested the model by comparing with the results of random distribution ofplants. The tests show that the model results are very close to the averagesof the random distributions. This model is efficient in computation, and canbe included in vegetation models to simulate long-term transient responsesof plant communities to climate change. The code and a user's manual areprovided as Supplement of the paper.