Summary of the Provided Article:

Offset Periods and Litterfall Fluxes

The article discusses the deciduous phenology algorithms in the model, which specify the occurrence of litterfall during offset periods. Only leaf and fine root state variables are subject to litterfall fluxes during these periods.

Carbon Fluxes from Display Pools into Litter:
- Calculated using equations that vary based on whether the current timestep is the final offset timestep (t_offset = Δt) or not.
- The rate coefficient r_xfer_off linearly increases the litterfall rate throughout the offset period.
- For bioenergy crops, the harvested fraction of aboveground biomass (leaf & livestem) is accounted for using the biofuel_harvfrac parameter.

Nitrogen Fluxes during Litterfall:
- Account for the retranslocation of nitrogen out of the displayed leaf pool prior to litterfall (NF_leaf,retrans).
- Retranslocation of nitrogen out of fine roots is assumed to be negligible.
- Nitrogen fluxes to litter are calculated based on the carbon fluxes and the C:N ratios of leaf litter and fine roots.

The summary captures the key aspects of the article, including the calculation of carbon and nitrogen fluxes during the offset periods and the special considerations for bioenergy crops.