# Differences

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 plantmodel [2017/11/10 09:09] plantmodel [2017/11/10 09:09] (current) 2012/07/02 00:59 created Line 1: Line 1: + ====== [PLANTMODEL] Section ====== + + ===== Purpose ===== + To calculate the transpiration of plants, it is necessary to know the actual stomata resistance.\\ + The stomata are active components of the plant system and react on environmental impacts such as solar input, air temperature and water availability in the soil. + + ENVI-met provides two methods for calculating the stomata resistance: A simple approach based on the work of Deardorff (1978) and a very sophisticated approach called A-gs model following the work of Jacobs (1994) (for exact references please refer to the papers available on the UNCONVERTED WINHELP MACRO:! ''ExecFile("www.envi-met.com")ENVI-met webpage'') + + The Deardorff approach scales an explicitly given maximum value of the stomata resistance with respect to the solar input and the water availability whereas the A-gs model calculates the photosynthesis rate of the plant and concludes from that to the C02 demand and finally to the state of the stomata. + + **We recommend the use of the A-gs model as it is more plant physiologically based than the Deardorff model.** + + To choose the model, use the [PLANTMODEL] section: + + + 00: [PLANTMODEL] _____________Settings for plant model + 01: Stomata res. approach (1=Deardorff, 2=A-gs)  =2 + 02: Background CO2 concentration [ppm]           =350 + + + + ===== What do the lines mean? ===== + + === 01: Stomata res. approach (Default 2, A-gs) === + Select the stomata resistance model to be used in the simulation. + + === 02: Background CO2 concentration [ppm] (Default 350 ppm) === + Sets the background CO2 concentration. Only needed for the A-gs model.\\ + Remark: If other sources in the model are of the CO2 type, they will add up to the CO2 concentration.