ECSO 0037 (ANPP) is a annual flux, so the time interval has to be 'year'

[mobb]

don't know where to constrain that.

[mobb]

since 'year' is implied, often the units (std) are simply areal biomass (no time interval). If this is going to stay in a flux group (parent node is Primary production carbon flux) - where conceptually, it belongs - then that's an argument for not constraining the parent node to a unit that includes time.