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plantphys / gsti

A project focused on the development of generalized spectra-trait models for the prediction of leaf photosynthetic capacity. This includes models focused on the prediction of leaf nitrogen, leaf mass per area (LMA), leaf water content (LWC), Vcmax, Jmax and dark respiration.
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Rday / Rdark / One point method #44

Open JulienLamour opened 1 year ago

JulienLamour commented 1 year ago

From our meeting, I agree that we should add the ability to include dark-adapted Rdark datasets. However, when reading Burnett et al. 2019 and De Kauwe et al. 2016 I see that the one-point method was tested using a Rday (estimated from A_Ci curve in both method). From what I remember, Rday estimated from A-Ci curve is very different from Rdark. So I am not sure how relevant it is to add a Rdark option in the one point method and if that could bias Vcmax estimates. Any thought? In all cases I will include a Rdark description for people who want to include dark respiration measurement independently from the one point method.

serbinsh commented 1 year ago

@JulienLamour this is a good point. I do think that we and others have been using Rday/Rdark interchangeably in the 1 pt calc. @DavidsonKen thoughts on this?

DavidsonKen commented 1 year ago

@serbinsh @JulienLamour The 1pt really should be Rdark not light acclimated Rday, or at least that's where the 1.5% of Vcmax assumption comes from. I think its important to give the option of using your own Rdark/Rday value as long as people specify what the value is

serbinsh commented 1 year ago

I think the concern is that Rday is generally biased low and Rdark tends to be closer to the "true" respiration and as such the values of 1pt will be biased if using Rday. So I am happy to stick with Rdark but wonder if we should also use Rday or if only Rday revert to a 0.015*vcmax assumption?