Physiological measurements such as respiration rate and assimilation rate depend
ID: 30833 • Letter: P
Question
Physiological measurements such as respiration rate and assimilation rate depend on temperature.
Most papers report tissue temperature (e.g. leaf temperature for leaf measurements), although some report air temperature.
My goal is to compare measurements in the literature. I use leaf temperature at time of measurement to adjust the rates to a common temperature. Currently, I assume that if leaf temperature is not available, it is the same as air temperature. (This is often assumed in papers where the leaf temperature was not measured).
Is there a way to estimate the difference between air temperature and leaf temperature? I can get fairly good estimates of other physiological traits (e.g. leaf thickness, albedo, stomatal conductance) as well as climate data (e.g. humidity, soil moisture content).
My model is:
And I currently assume X = 0 in my calculations
Is there a better way to estimate X?
Under what conditions would X < 0? X > 0?
Explanation / Answer
One way to do this is to use the "humid operative temperature" equation, or something similar. A variant of this equation, specifically for estimating leaf temperature, is derived using a leaf energy balance equation in chapter 14.1 of the Environmental Biophysics book (cited below).
I'll let you look up the actual equation since I'm not sure how to do math symbols here. But, in addition to air temperature, you will need to know a few pieces of information:
That's about it - its a somewhat hairy calculation, but if you have standard weather data and a little knowledge of the plants you are estimating the leaf temperature of, it should be manageable.