title: Spatial heterogeneity of physicochemical properties explains differences in microbial composition in arid soils from Cuatro Cienegas, Mexico.
abstract: Arid ecosystems are characterized by high spatial heterogeneity, and the variation among vegetation patches is a clear example. Soil biotic and abiotic factors associated with these patches have also been well documented as highly heterogeneous in space. Given the low vegetation cover and little precipitation in arid ecosystems, soil microorganisms are the main drivers of nutrient cycling. Nonetheless, little is known about the spatial distribution of microorganisms and the relationship that their diversity holds with nutrients and other physicochemical gradients in arid soils. In this study, we evaluated the spatial variability of soil microbial diversity and chemical parameters (nutrients and ion content) at local scale (meters) occurring in a gypsum-based desert soil, to gain knowledge on what soil abiotic factors control the distribution of microbes in arid ecosystems. We analyzed 32 soil samples within a 64 m(2) plot and: (a) characterized microbial diversity using T-RFLPs of the bacterial 16S rRNA gene, (b) determined soil chemical parameters, and (c) identified relationships between microbial diversity and chemical properties. Overall, we found a strong correlation between microbial composition heterogeneity and spatial variation of cations (Ca(2), K(+)) and anions (HCO[Formula: see text], Cl(-), SO[Formula: see text]) content in this small plot. Our results could be attributable to spatial differences of soil saline content, favoring the patchy emergence of salt and soil microbial communities.
authors.affiliation: Instituto de Ciencias del Mar y Limnología, Unidad Académica de Ecología y Biodiversidad Acuática, Universidad Nacional Autónoma de México, Mexico City, Mexico; Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana, Unidad Cuajimalpa, Mexico City, Mexico.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pajares
authors.affiliation: Instituto de Ecología, Laboratorio Nacional de Ciencias de la Sostenibilidad, Universidad Nacional Autónoma de México , Mexico City , Mexico.
authors.forename: Ana E
authors.initials: AE
authors.lastname: Escalante
authors.affiliation: Instituto de Ecología, Departamento de Ecología Evolutiva, Universidad Nacional Autónoma de México , Mexico City , Mexico.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Noguez
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México , Morelia , Michoacán , Mexico.
authors.forename: Felipe
authors.initials: F
authors.lastname: García-Oliva
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México , Morelia , Michoacán , Mexico.
authors.forename: Celeste
authors.initials: C
authors.lastname: Martínez-Piedragil
authors.affiliation: Instituto de Geografía, Universidad Nacional Autónoma de México , Mexico City , Mexico.
authors.forename: Silke S
authors.initials: SS
authors.lastname: Cram
authors.affiliation: Instituto de Ecología, Departamento de Ecología Evolutiva, Universidad Nacional Autónoma de México , Mexico City , Mexico.
authors.forename: Luis Enrique
authors.initials: LE
authors.lastname: Eguiarte
authors.affiliation: Instituto de Ecología, Departamento de Ecología Evolutiva, Universidad Nacional Autónoma de México , Mexico City , Mexico.
authors.forename: Valeria
authors.initials: V
authors.lastname: Souza
keywords: Arid soils; Biological soil crusts; Cuatro Cienegas Basin; Physicochemical properties; Spatial heterogeneity; T-RFLPs