Beschreibung:
One-hundred twenty-two species of seed plants, representing 95 genera and 35 families are documented for the 7,700 ha Mohawk Dune Field and its immediate surroundings, located in Yuma County, Arizona, USA. Three major habitats were studied: dunes, adjacent sand flats, and playa. The dunes (including interdune swales) support 78 species, of which 13 do not occur on the adjacent non-dune habitats. The adjacent non-dune habitats (sand flats and playa) support 109 species, of which 43 were not found on the dunes. The total flora has 81 annual species, or 66% of the flora. The dune flora has 63 annual (ephemeral) species, or 81% of the flora—one of the highest percentages of annuals among any regional flora. Of these dune annuals, 53 species (84%) develop during the cool season. No plant taxon is endemic to the Mohawk region. There are 8 dune, or sand adapted, endemics—Cryptantha ganderi, Dimorphocarpa pinnatifida, Dicoria canescens, Ditaxis serrata, Pleuraphis rígida, Psorothamnus emoryi, Stephanomeria schottii, Tiquilia plicata-all of which are found on nearby dune systems. Two of them (C. ganderi and S. schottii) are of limited distribution, especially in the USA, and have G2 Global Heritage Status Rank. There are four non-native species in the dune flora (Brassica tournefortii, Mollugo cerviana, Sonchus asper, Schismus arabicus), but only Brassica and Schismus seem to pose serious threats to the dune ecosystem at this time. The Mohawk Dune field is within the Lower Colorado Valley phytogeographic region of the Sonoran Desert and located within the Barry M. Goldwater Military Range. This unique dune system, largely unaffected by human activities, is recommended as a site for baseline studies of plant migrations and population dynamics affected by global climatic change. Ciento veintidos especies de espermatófitos, que representan 95 géneros y 35 familias se documentan para las 7,700 ha del Mohawk Dune Field y sus alrededores, en el condado de Yuma, Arizona, USA. Se estudiaron tres grandes habitats: dunas, arenales planos, y playas. Las dunas (incluyendo las depresiones interdunares) tienen 78 especies, de las que 13 no se dan en los habitats no dunares adyacentes. Los hábitats adyacentes no dunares (arenales planos y playa) tienen 109 especies, de las que 43 no se encontraron en las dunas. La flora total tiene 81 especies anuales, o el 66% de la flora. La flora dunar tiene 63 especies anuales (efímeras), o el 81% de la flora—uno de los porcentajes más altos de anuales en las floras regionales. De estas anuales dunares, 53 (84%) se desarrollan durante la estación fría.