If you take a look in the WRF/run/VEGPARM.TBL file, you will see ALBEDOMIN and ALBEDOMAX, corresponding to each landuse type. The Noah LSM scheme reads this file, then calculates albedo based on the vegetation cover fraction, and the max/min albedo. For more details, you can see the file WRF/phys/module_sf_noahlsm.F.