Tucson Mountain District, Saguaro National Park Vegetation Inventory, Mapping,andCharacterization Report,Saguaro National Park mix of old andmix of new alluvium, though igneous inclusions underlay some hillslope examples. lowest elevations. Elevation ranges upto 878meters (2,880ft). The geology this of association isgenerally a northwestern boundaries. It typically occurs on very gravelly alluvial fans and low hillslopes inthe district’s This community covers the 12%(1,222ha/3,020 ac)of Tucson Mountain District, mainly along the west and from 3%to 6%. bur ragweed (A. deltoidea) isaconsistent (1.0)dominant inthe field stratum, contributing with cover ranging fulgida), buckhorn cholla (Cylindropuntia acanthocarpa ), and cactus apple (Opuntiaengelmannii).Triangle approaching 5%.In order from most to least frequent, these species include chain-fruit cholla (Cylindropuntia When combined, cactus species are the next most-common group subcanopy of species, with average cover providing consistent (1.0)cover that typically ranges from 3%to 10%,with some dense inclusions upto 20%. classification plot. Creosote (L. tridentata)isthe most dominant species, all examples this of community, with seven amedian of individuals per Saguaro (Carnegiea gigantea) ispresent asalow-density associate in ranges from 2%to 5%,with occasional dense inclusions upto 10%. microphylla) grows asashort (3m)tree contributing cover that typically nated by triangle burragweed (Ambrosia deltoidea). Yellow paloverde (P. succulents,of and asparse (<5%cover) field stratum (<0.5m) domi- cover) subcanopy (0.5–2m)dominated by creosote and adiverse suite yellowm) of paloverde (Parkinsonia This community ischaracterized by anopen(<10%cover) canopy (>2 (Yellow paloverde)/Creosote-MixedCactiTriangle burragweedShrublandAssociation(P) 13. (Parkinsoniamicrophylla) Shrubland Association(P)
/ microphylla), avariable (5–20% Larreatridentata-MixedCacti/Ambrosiadeltoidea • • • • • Common species
Ambrosia deltoidea Opuntia engelmannii Cylindropuntia fulgida Larrea tridentata Parkinsonia microphylla
Tucson Mountain District, Saguaro National Park