Open access publications in the SLU publication database

Abstract

The theory of the simulation model SPAC-GROWTH is presented. The model simulates transpiration, evaporation of intercepted water and growth for horizontally homogeneous cultivations for either non-woody or woody plants. The description aims to serve as a tool when using the model. Transpiration and evaporation simulations are based on the SPAC (Soil Plant Atmosphere Continuum) concept where the soil water potential and vapour pressure deficit of the air are input variables creating the driving force for water flow. The pathway of water through the system is pepresented by characteristic resistances. The growth is based on the "water use efficiency" concept and is allocated between leaf+stem, root and grain biomass. The plant size affects the water flow mainly through the leaf area development. The presentation also includes functions for converting daily weather input data to minute values required by the water flow simulations. Two simulation examples show all input needed by the model and some output of the model.