The palms (Arecaceae) of Sonora, Mexico

This publication is an account of the palms (Arecaceae) in the state of Sonora in northwestern Mexico. Six native palm species in three genera are recorded for Sonora: Brahea with four species, and Sabal and Washingtonia each with one species. Relationships and taxonomy within Brahea, especially B. elegans, remain unresolved. Brief botanical descriptions, taxonomic synopses, local names, identification keys, conservation status and recommendations, and distributional and ethno- botanical information are provided for each species. Basionyms and types are cited. Distributions are documented with citations of nearly all herbarium specimens known to us from Sonora. Many palm populations in this arid and semiarid region are threatened by development and in some cases over- exploitation. There is an urgent need for formal management and conservation action for local pop- ulations, although as a whole none of these species in Sonora are rare or immediately threatened

The Euphorbiaceae of Sonora, Mexico

This publication is an account of the Euphorbiaceae in the state of Sonora, México. Nineteen genera, 143 species, and three additional varieties are recorded for the state; three species expected within the state are also treated. One species of Acalypha and three species and one subspecies of Euphorbia are described. Dichotomous keys for the identification of genera and species are provided. Bibliographic citations, type information, synonyms, brief habit descriptions, times of reproduction, habitat preferences as well as elevational range within Sonora, geographical distribution, and representative specimens are given for each species. When appropriate, notes on uses, taxonomic or nomenclatural problems, and other points of interest are discussed

Controls of plant diversity and composition on a desert archipelago

Aim: With the most robust floristic data set for any arid archipelago, we use statistical modeling to determine the underlying controls of plant diversity and species composition. Location: The study was undertaken in the Midriff Islands of the Gulf of California, Mexico. Methods: Using the area-diversity relationship we estimate the power coefficient z with generalized linear models (GLM). We tested eight predictors (area, human presence, habitat diversity, topography, distance to mainland, island type, precipitation, and seabird dynamics) using a step-wise process on the same GLM procedure. Plant species composition was assessed by conducting a non-standardized principal component analysis on a presence-absence matrix of the 476 (plant species) x 14 (islands). Finally, families were tested for over or under representation with a X-2 analysis subjected to a Bonferroni correction. Results: The classic species-area model explained 85% of the variance in island plant diversity and yielded a slope (z) of 0.303 (+/- 0.01). When the effect of area is removed, four additional factors were shown to account for observed variation; habitat diversity (34%), seabird dynamics (23%), island type (21%), topography (14%). Human presence and distance to mainland were not predictors of species richness. Species composition varies significantly with island area; small islands have a particular flora where certain families are overrepresented, such as Cactaceae, while the flora of larger islands is strongly dependent on the continental source. Main conclusions: The factors that control diversity levels are expressions of geology, landscape heterogeneity, and land-sea connections. Species assemblages in small islands are governed by copious marine nutrients in the form of guano that depress species diversity. Distance to mainland and human presence hold no predictive power on diversity. The results show these islands to be isolated arid ecosystems with functioning ecological networks.National Science Foundation; UC MEXUSOpen access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

High proportion of cactus species threatened with extinction

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Consejo Nacional de Ciencia y Tecnologí