Reviewers Rapid Assessment Model ZonesVegetation Type

This type typically occurs on upland flats, benches, gentle slopes or well drained valley and draw bottoms in areas with less than 12 inches precipitation. Vegetation Description Vegetation is shrubland dominated by creosote bush, bur sage, opuntia, and palo verde, saguaro, with intermingled forbs. Blackbrush, ephedra, spiny hopsage, and fringed sage would be found in the Colorado Plateau areas. Could be crosswalked with Ecological System CES302.731, CES302.737, CES302.738, CES302.756, CES302.760, CES302.035, CES302.761, CES304.763. Disturbance Description Fire regime group III, infrequent mixed. The mean fire interval is generally greater than 75 years with high variation due to year to year variation in drying of shrub foliage, shrub mortality, grass, and forb production related to drought and moisture cycles combined with variation in ignitions and associated fire weather. Fire years are typically correlated with high spring moisture years in geographic areas dominated by cool season moisture and high summer moisture in areas dominated by monsoon season rains. Fire intervals would have been much longer in the dry ends of this PNV with return intervals on the order of 200 + years. Fire size would have been small because of the discontinuous fuels