landcover descriptions for the southwest regional gap analysis project

SOURCESReferences: Brown 1982, Dick-Peddie 1993, MacMahon 1988, Muldavin et al. 2000b, Muldavin et al. 2002Last updated: 20 Feb 2003Stakeholders: WCS, SCS, LACDConcept Author: NatureServe Western Ecology TeamLeadResp: WCSS063 SONORAN PALOVERDE-MIXED CACTI DESERT SCRUBDivision 302, Shrubland, CES302.761Spatial Scale & Pattern: MatrixClassification Confidence: mediumRequired Classifiers: Natural/Semi-natural, Vegetated (>10% vasc.), UplandDiagnostic Classifiers: Lowland [Foothill], Lowland [Lowland], Shrubland (Shrub-dominated),Tropical/Subtropical [Tropical Xeric], Temperate [Temperate Xeric], Aridic, Xeromorphic Shrub, Succulent Shrub,Cacti-dominatedNon-Diagnostic Classifiers: Sideslope, Toeslope/Valley Bottom, Alkaline Soil, Sand Soil Texture, Broad-LeavedDeciduous Shrub, Succulent ForbConcept Summary: This ecological system occurs on hillsides, mesas and upper bajadas in southern Arizona andextreme southeastern California. The vegetation is characterized by a diagnostic sparse, emergent tree layer ofCarnegia gigantea (3-16 m tall) and/or a sparse to moderately dense canopy codominated by xeromorphicdeciduous and evergreen tall shrubs Parkinsonia microphylla and Larrea tridentata with Prosopis sp., Olneyatesota, and Fouquieria splendens less prominent. Other common shrubs and dwarf-shrubs include Acacia greggii,Ambrosia deltoidea, Ambrosia dumosa (in drier sites), Calliandra eriophylla, Jatropha cardiophylla, Krameriaerecta, Lycium spp., Menodora scabra, Simmondsia chinensis, and many cacti including Ferocactus spp.,Echinocereus spp., and Opuntia spp. (both cholla and prickly pear). The sparse herbaceous layer is composed ofperennial grasses and forbs with annuals seasonally present and occasionally abundant. On slopes, plants are oftendistributed in patches around rock outcrops where suitable habitat is present.DISTRIBUTIONRange: Southern Arizona and extreme southeastern California.Ecological Divisions: 302TNC Ecoregions: 23:CSubnations/Nations: AZ:c, CA:c, MXBC:c, MXSO:c, NV:?CONCEPTAlliances and Associations:• ACACIA GREGGII SHRUBLAND ALLIANCE (A.1036)Acacia greggii - Parkinsonia microphylla Shrubland (CEGL001340)• AMBROSIA DELTOIDEA SHRUBLAND ALLIANCE (A.852)Ambrosia deltoidea / Simmondsia chinensis Shrubland (CEGL000953)• CARNEGIA GIGANTEA WOODED SHRUBLAND ALLIANCE (A.885)Carnegia gigantea / Prosopis velutina Wooded Shrubland (CEGL001389)• FOUQUIERIA SPLENDENS SHRUBLAND ALLIANCE (A.863)Fouquieria splendens / Bouteloua curtipendula Shrubland (CEGL001376)Fouquieria splendens / Bouteloua hirsuta Shrubland (CEGL001377)• LARREA TRIDENTATAWOODED SHRUBLAND ALLIANCE (Proposed)• OPUNTIA BIGELOVII SHRUBLAND ALLIANCE (A.877)Opuntia bigelovii Shrubland [Placeholder] (CEGL003065)• PARKINSONIA FLORIDA - OLNEYA TESOTA WOODLAND ALLIANCE (A.588)Parkinsonia florida - Olneya tesota Woodland [Placeholder] (CEGL003035)• PARKINSONIA FLORIDA SHRUBLAND ALLIANCE (A.882)Parkinsonia florida / Hilaria belangeri Shrubland (CEGL001374)• PARKINSONIA MICROPHYLLA SHRUBLAND ALLIANCE (A.883)Parkinsonia microphylla - Larrea tridentata Shrubland (CEGL001375)• SIMMONDSIA CHINENSIS SHRUBLAND ALLIANCE (A.853)Simmondsia chinensis - Parkinsonia microphylla Shrubland (CEGL000983)• California community types:• Teddy-bear Cholla Succulent Scrub (33.050.00)• Ocotillo open-tall scrub (33.090.00)Ecological Systems: Copyright © 2003 NatureServe 90