The new grass code is optional with the flag "igrass"
igrass = 0 Old Code
igrass = 1 New Code

The main changes:
1) Sapwood has been split into above and below ground components (bsapwooda/bsapwoodb)
2) bdead = 0 for grass
3) hite = f(bleaf), and changes daily
4) grasses put all stored carbon into reproduction when they reach maximum hite/bleaf
5) allometric functions have been made more generic i.e. size2bl (intended to replace dbh2bl) ingests both dbh and hite so it can decide within the function which to use.
6) DBH(effective) is still stored as a value but not used for grass calculations