I am really struggling with the formulation of my linear mixed effect model.
I need a lme function in which several fixed effects involved and random effects.
The fixed effects are soilmoist, soiltemp and airtemp having an influence on the CO2 respiration rate that is visualized below. Moreover, 2 random effects are involved, the potid and date. How can I generate a lme function that matches these requirements?
This is the function I have come up with so far. However, this results in a negative slope....
random=list(~0+DT|PotID, ~DT|Date), data =Dark, control = ctrl)