hut104
commented
2 years ago The approach in NG is as described in the wheat model documentation for Wheat in NG. There were biomass-based approaches in classic, but these are not used in the current wheat model in NG.
From: iMarang @.> Sent: Wednesday, 13 April 2022 10:50 AM To: APSIMInitiative/ApsimX @.> Cc: Subscribed @.***> Subject: [APSIMInitiative/ApsimX] Height model description (Issue #7233)
Hi, I've used APSIM next gen for my phd thesis and have described the way height is simulated as:
"In APSIM, height is modelled as daily increments of potential height growth modified by water stress, with potential height set according to linear interpolation with growth stage."
This is the description in the WheatDocumentation.pdf (3.4.4.1) I accessed from herehttps://apsimnextgeneration.netlify.app/modeldocumentation/ (which I can't download from currently by the way)
"Height is used by the MicroClimate model to calculate the aerodynamic resistance used for calculation of potential transpiration. Calculates the potential height increment and then multiplies it by the smallest of any childern functions (Child functions represent stress)." The only stress listed is water stress (Fw).
I've been advised by my thesis reviewer that this is incorrect, but that height is actually derived from calculated biomass. I think this is the method used in APSIM classic, not next gen, but I can't find details in the APSIM classic wheat documentation referring to height at all. I understand biomass accumulation is controlled through nutrient and water supply and radiation interception, distributed according to the arbitrators potential growth vs stress-limited growth calculations, but height seems directly connected to thermal time accumulation development stage (aka phenology) progression, and not biomass per se.
Can you advise please? My reviewer has much more experience with APSIM than I, but I can't find any documentation to support their description.
By the way, thank you very much for your excellent model and support. Ian
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iMarang
Hi, I've used APSIM next gen for my phd thesis and have described the way height is simulated as:
"In APSIM, height is modelled as daily increments of potential height growth modified by water stress, with potential height set according to linear interpolation with growth stage."
This is the description in the WheatDocumentation.pdf (3.4.4.1) I accessed from here (which I can't download from currently by the way)
"Height is used by the MicroClimate model to calculate the aerodynamic resistance used for calculation of potential transpiration. Calculates the potential height increment and then multiplies it by the smallest of any childern functions (Child functions represent stress)." The only stress listed is water stress (Fw).
I've been advised by my thesis reviewer that this is incorrect, but that height is actually derived from calculated biomass. I think this is the method used in APSIM classic, not next gen, but I can't find details in the APSIM classic wheat documentation referring to height at all. I understand biomass accumulation is controlled through nutrient and water supply and radiation interception, distributed according to the arbitrators potential growth vs stress-limited growth calculations, but height seems directly connected to thermal time accumulation development stage (aka phenology) progression, and not biomass per se.
Can you advise please? My reviewer has much more experience with APSIM than I, but I can't find any documentation to support their description.
By the way, thank you very much for your excellent model and support. Ian