Bioclimates and vegetation along the Pacific basin of Northwestern Mexico

We describe relationships between the bioclimates and vegetation of the northwest of Mexico, including the Baja California peninsula and the stretch of the Pacific basin between the states of Sonora and Colima, a transition zone from the most arid deserts of North America to tropical rainforests. Links were inferred from temperature and rainfall data obtained from 453 weather stations that were used to construct climatograms, calculate several climate indices and describe main latitudinal and longitudinal trends, and from sampling the vegetation around these stations. Across this extensive area, spanning some 14Zapotitlán of both latitude and longitude as well as three zonobiomes and two zonoecotones, two macrobioclimates were identified, Mediterranean and Tropical, within which we were able to distinguish six bioclimates. For each of these bioclimates, we find different types of zonal and azonal vegetation, whose floristic composition and physiognomy are described here. Zapotitlán 2010 Springer Science+Business Media B.V

Statistical measures of fidelity applied to diagnostic species in plant sociology

The idea of a diagnostic species is an important concept in plant sociology. However, since over a century ago, when the term "association" was introduced, the identification of diagnostic species has been among the most controversial topics in phytosociological practice. With the aim of promoting methodological standardization in plant sociology, this paper addresses: 1) the need to distinguish between the concepts and methods involved in the definition of syntaxa (analysing relev�s, characterization, diagnosis, naming and typification), and 2) the need to support and improve existing syntaxonomical classification schemes using statistical measures of fidelity to identify diagnostic species. The phytosociological literature describes numerous different approaches to the designation of diagnostic species. Here, we examine two such approaches to determine diagnostic species using as an example the class Atriplici julaceae-Frankenietea palmeri within the context of a data set of 5092 relev�s taken of coastal plant communities distributed along the Pacific rim of North America. Diagnostic species were determined using both the phi-coefficient of association to detect differential species and the Ochiai index to designate character species. Our findings support the results obtained by combining classic phytosociological methods (expert knowledge, rearrangement of relev� tables, presence tables, etc.) with clustering methods