Tucson Mountain District, National Park Vegetation Inventory, Mapping,andCharacterization Report,Saguaro National Park This association isone five of found inboth the TMD and the Rincon Mountain District. soil. within the watercourse, are dominated by fine gravel and sand. The adjacent slopes are more commonly bare from 820to 935meters (2,690–3,067ft). The surface cover ischaracterized by deep, well-drained soils that, restricted to low-angle (<5%),typically north-flowing washes that bisect the broad alluvial fans and low hills This community covers the 2.6%(265ha/655 ac)of TMD. It iswidespread throughout the alluvial fans. It is mon associates. for each species. The field layer (<0.5m)isextremely sparse (<5%),without any consistent dominants or com- consistent creosote (>0.75)mixof (L. tridentata ) and catclaw acacia (S. greggii), with anaverage cover 6% of consistent cover throughout, with anaverage around 20%. The remainder the of layer iscomposed a of ( vides cover upto of 5%. The shrub layer isconsistently (1.0)dominated by large (upto 3m)whitethorn acacia District (TMD), desert ironwood that canco-occur or occasionally replace velvet mesquite (P. velutina) inthe canopy. At the Tucson Mountain florida) are sparse (1–2%cover), inconsistent (0.5and 0.4)associates paloverde ( microphylla) and blue paloverde ( Parkinsonia along the the margins of watercourse, with cover around of 6%.Yellow is aconsistent (1.0)component, typically present aslarge (4m) tata) and catclaw acacia ( greggii). Velvet mesquite (P. velutina) ( [60]% cover) shrub layer (0.5–2m)dominated by whitethorn acacia canopy velvet (>2m)of mesquite (Prosopis velutina) and adense (20–40 This shrubland community ischaracterized by asparse (<10%cover) Association (P) (Velvet mesquite)/Whitethornacacia(Creosote-Catclawacacia)IntermittentlyFloodedShrubland Intermittently FloodedShrublandAssociation(P) 39. (Prosopisvelutina) V. constricta) that canform dense thickets along and within the watercourse. Overall, this species provides Vachellia constricta), with common associates creosoteLarrea ( triden-

/ Vachellia constricta( ( tesota) isanoccasional (0.57)associate that, when present, pro - -Senegaliagreggii) • • • • Common species

Senegalia greggii Larrea tridentata Vachellia constricta Prosopis velutina Tucson Mountain District, Saguaro National Park Rincon Mountain District, Saguaro National Park Vegetation Inventory, Mapping,andCharacterization Report,Saguaro National Park This association isone five of found inboth the RMDand the Tucson Mountain District. are dominated by fine gravel and sand while the adjacent slopes are more commonly bare soil. (2,690–3,067 ft.). The surface cover ischaracterized by deep, well-drained soils that, within the watercourse, (<5%), typically north-flowing washes that bisect the broad alluvial fans and low hills from 820 to 935 meters ily occurs near the Douglas Spring trailhead and the Forest LoopRoad. It isrestricted to low-angle This community covers the 0.6%(152ha/376 ac)of Rincon Mountain District (RMD). At the RMD, it primar field layer (<0.5m)isextremely sparse (<5% cover), without any consistent dominants or common associates. creosoteof (L. tridentata ) and catclaw acacia (S. greggii), with anaverage cover 6%for of each species. The out, with anaverage around of 20%. The remainder the of shrub layer iscomposed aconsistent of (>0.75)mix form dense thickets along and within the watercourse. Overall, this species provides consistent cover through - The shrub layer isconsistently (1.0)dominated by large (upto 3m)whitethorn acacia ( (0.5 and 0.4)associates that canco-occur or occasionally replace velvet mesquite (P. velutina) inthe canopy. paloverde (Parkinsonia florida)are sparse (1–2%cover), inconsistent aroundof 6%.Yellow paloverde ( ) and blue ent aslarge (4m)trees along the the margins of watercourse with cover mesquite (P. velutina) isaconsistent (1.0)component, typically pres- sote (Larrea tridentata)and catclaw acacia (Senegalia greggii). Velvet whitethorn acacia (Vachellia constricta), with common associates creo- and adense (20–40[60]%cover) shrub layer (0.5–2m)dominated by (<10% cover) canopy velvet (>2m)of mesquite (Prosopis velutina) This xeroriparian shrubland community ischaracterized by asparse Association (P) (Velvet mesquite)/Whitethornacacia(Creosote-Catclawacacia)IntermittentlyFloodedShrubland Intermittently FloodedShrublandAssociation(P) 39. (Prosopisvelutina)

/ Vachellia constricta( Larrea tridentata-Senegaliagreggii) • • • • Common species

Senegalia greggii Larrea tridentata Vachellia constricta Prosopis velutina V. constricta) that can - Rincon Mountain District, Saguaro National Park