Important diversity of EFN morphology was foundin the coastal plant community studied. Both vascularized and non-vascularized EFNs are observed in plants and, for the latter, previously non-existent morpho-secretory characterizations are provided with a methodological approach to study them. It is recommended that studies relating EFN attributes (i.e. morphology, distribution) with their differential visitation by insects (i.e. ants) and the cost of maintenance to the plants are carried out to understand the evolution of these glands.

RESUMENPara entender los procesos de los ecosistemas desde un punto de vista funcional es fundamental entender las relaciones entre la variabilidad climática, los ciclos biogeoquímicos y las interacciones superficie-atmósfera. En las últimas décadas se ha aplicado de manera creciente el método de covarianza de flujos turbulentos (EC, por sus siglas en inglés) en ecosistemas terrestres, marinos y urbanos para medir los flujos de gases de invernadero (p. ej., CO 2 , H 2 O ) y energía (p. ej., calor sensible y latente). En diversas regiones se han establecido redes de sistemas EC que han aportado información científica para el diseño de políticas ambientales y de adaptación. En este contexto, el presente trabajo delimita el marco conceptual y técnico para el establecimiento de una red regional de medición de flujos de gases de efecto invernadero en México, denominada MexFlux, cuyo objetivo principal es mejorar nuestra comprensión de la forma en que la variabilidad climática y la transformación ambiental influye en la dinámica de los ecosistemas mexicanos ante los factores de cambio ambiental global. En este documento se analiza primero la importancia del intercambio de CO 2 y vapor de agua entre los ecosistemas terrestres y la atmósfera. Después se describe brevemente la técnica de covarianza de flujos turbulentos para la medición de éstos, y se presentan ejemplos de mediciones en dos ecosistemas terrestres y uno urbano en México. Por último, se describen las bases conceptuales y operativas a corto, mediano y largo plazo para la continuidad de la red MexFlux. 325-336 (2013) Atmósfera 26(3), 326 R. Vargas et al. ABSTRACTUnderstanding ecosystem processes from a functional point of view is essential to study relationships among climate variability, biogeochemical cycles, and surface-atmosphere interactions. Increasingly during the last decades, the eddy covariance (EC) method has been applied in terrestrial, marine and urban ecosystems to quantify fluxes of greenhouse gases (e.g., CO 2 , H 2 O) and energy (e.g., sensible and latent heat). Networks of EC systems have been established in different regions and have provided scientific information that has been used for designing environmental and adaptation policies. In this context, this article outlines the conceptual and technical framework for the establishment of an EC regional network (i.e., MexFlux) to measure the surface-atmosphere exchange of heat and greenhouse gases in Mexico. The goal of the network is to improve our understanding of how climate variability and environmental change influence the dynamics of Mexican ecosystems. First, we discuss the relevance of CO 2 and water vapor exchange between terrestrial ecosystems and the atmosphere. Second, we briefly describe the EC basis and present examples of measurements in terrestrial and urban ecosystems of Mexico. Finally, we describe the conceptual and operational goals at short-, medium-, and long-term scales for continuity of the MexFlux network.

Ethrel (2-chloroethylphosphonic acid) applied in lanolin paste at concentrations of 0.4, 1.6, 6.2, or 10.8% to stems of 3-month-old Ulmus americana seedlings greatly altered stem anatomy within 41 days. Application of ethrel at 1.6% or higher concentration was followed by greatly increased bark thickness primarily as a result of an increase in the amount of phloem and intercellular spaces. Xylem increment was increased following treatment with 0.4 or 1.6% ethrel and reduced by 6.2 or 10.8% ethrel. All concentrations of ethrel increased the number of vessels, reduced vessel diameters, and induced an increase in ray width and size of the individual ray cells. Ethrel at 6.2 or 10.8% inhibited differentiation of fibres, many of which were poorly developed and contained protoplasm and nucleL Ethrel also stimulated accumulation of dark-staining organic deposits in the ray parenchyma cells, axial parenchyma cells, and immature fibres. The data indicate a role of ethylene in control of growth and anatorny of stems.

We determined the influence of resin ducts, sap content, and fruit physicochemical features of four mango cultivars (Criollo, Manila, Ataulfo, and Tommy Atkins) on their susceptibility to the attack of the two most pestiferous fruit fly species infesting mangoes in Mexico: Anastrepha ludens (Loew) and Anastrepha obliqua (Macquart). We performed three studies: 1) analysis of resin ducts in mango fruit exocarp to determine the density and area occupied by resin ducts in each mango cultivar, 2) assessment of mango physicochemical features including fruit sap content, and 3) a forced infestation trial under field conditions using enclosed fruit-bearing branches to expose mangoes to gravid A. ludens or A. obliqua females. Infestation rates, development time from egg to prepupae and pupae, pupal weight, and percent of adult emergence, were assessed. 'Ataulfo' and 'Tommy Atkins' cultivars exhibited the highest resin duct density and sap content, the lowest infestation rate, and had a negative effect on immature development and pupal weight. In sharp contrast, 'Manila' and 'Criollo' cultivars, with the lowest resin duct density and sap content, were highly susceptible to A. ludens and A. obliqua attack. We conclude that sap content and the number, size, and distribution of resin ducts as well as firmness in mango fruit exocarp are all involved in the resistance of mango to A. ludens and A. obliqua attack.

Objectives Altitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, solar radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant communities modify soil processes in different ways, but it is not known how root traits influence soil biota at the community level. We collected data to investigate how elevation affects belowground community traits and soil microbial and faunal communities. This dataset comprises data from a temperate climate in France and a twin study was performed in a tropical zone in Mexico. Data description The paper describes soil physical and chemical properties, climatic variables, plant community composition and species abundance, plant community traits, soil microbial functional diversity and macrofaunal abundance and diversity. Data are provided for six elevations (1400–2400 m) ranging from montane forest to alpine prairie. We focused on soil biophysical properties beneath three dominant plant species that structure local vegetation. These data are useful for understanding how shifts in vegetation communities affect belowground processes, such as water infiltration, soil aggregation and carbon storage. Data will also help researchers understand how plant communities adjust to a changing climate/environment.