Tucson Mountain District, Saguaro National Park Vegetation Inventory, Mapping,andCharacterization Report,Saguaro National Park plants to take hold. are very common to dominant (35–65%)and canprovide the majority ground of cover, leaving little space for range from 35%slope upwards to vertical bands cliff dotted with vegetation. Rock and bedrock outcroppings very rocky north and northeast-facing crests, shoulders, and backslopes steep of mountain slopes. Gradients Mountain District, mainly inthe district’s northernmost section, north Picture of Rocks Road. It occurs on This community iscontained within atwo-association map class that covers the 3%(295ha/729 ac)of Tucson exsertum) and water jacket (Lycium andersonii) is wolfberry (Lycium the most dominant and consistent species inthe subcanopy (0.5–2m) as ashort (2m)tree or tall shrub, with cover 5–12[20]%. In of general, the vegetation islocated. Yellow paloverde (P. microphylla) ispresent coolerof temperatures and protected germination sites where much of rock cover, inthe form large, of rounded boulders, creates microclimates dominated by Berlandier’s wolfberry (Lycium berlandierihigh). The diverse understory mixed of shrubs and succulents, most commonly canopy yellow (>2m)of paloverde (Parkinsonia microphylla), with a This shrubland community ischaracterized by anopen(5–20%cover) Yellow paloverde/Berlandier’s wolfberry(MixedShrub)RockyShrublandAssociation(P) Association (P) 29. la arizonica) isaconsistent associate that canprovide occasional inclusions dominance, of with cover upto 5%. forbs, and perennial grasses with noconsistent dominants or common associates. Arizona spikemoss (Selaginel- ( acacia (Vachellia constricta), rough jointfir (Ephedra aspera), creosote (Larrea tridentata),and staghorn cholla subcanopy species include catclaw acacia (Senegalia greggii), spiny hackberry (Celtisehrenbergiana), whitethorn is aconsistent and characteristic component this of community, generally with 2–3%cover. Other noteworthy Cylindropuntia acanthocarpa ). The field stratum (<0.5m)is defined by a diverse suiteof subshrubs, perennial Parkinsonia microphylla/ spp.)— mostly Berlandier’s wolfberry (L. berlandieri), but Arizona desert-thornLycium ( Lycium berlandieri(MixedShrub)RockyShrubland

were also documented. Berlandier’s wolfberry (L. berlandieri) • • • • Common species

Celtis ehrenbergiana Vachellia constricta Lycium berlandieri Parkinsonia microphylla Tucson Mountain District, Saguaro National Park