Tropical Dry Forest In Mexico Research Articles

Variability Profiles for Line Transect Bird Censuses in a Tropical Dry Forest in Mexico

Seasonal and temporal patterns of species diversity and abundance in the avifauna of Chamela, Jalisco, Mexico, were studied in different habitats in the coastal tropical dry forest. Species richness did not differ among three different transects. The number of species was temporally homogeneous. Species diversity was similar for all three transects, but it changed to higher values during the rainy season at arroyo habitats and during the dry season (winter) at disturbed habitats. Population fluctuations observed in the second year of the study suggest that stochastic events such as droughts in this region may influence local population dynamics. Patterns of population fluctuation of resident species are discussed with regard to censusing methods and conservation priorities. Resumen. Se estudiaron los patrones estacionales y temporales de diversidad y abundancia de la avifauna de Chamela, Jalisco, México en distintos habitats de la selva baja caducifolia de la costa. La riqueza de especies no difiere entre transectos y es homogénea temporalmente. La diversidad de especies es similar entre transectos, pero el valor del índice aumenta durante la época húmeda a lo largo de los arroyos y durante la época de secas (invierno) en las zonas perturbadas. Las fluctuaciones en el tamaño de las poblaciones observadas durante el segundo año del estudio sugieren que eventos estocásticos como las sequías en la región pueden afectar la dinámica de las poblaciones a nivel local. Los patrones de fluctuaciones de las poblaciones de especies residentes son discutidos en términos de la metodología usada para censar y en cuanto a su prioridad de conservación.

Root system analysis of seedlings of seven tree species from a tropical dry forest in Mexico

Root attributes of tree seedlings of seven species from the tropical deciduous forest along the Pacific Coast of Mexico are described using morphometirc root system analysis. Mean relative growth rate, root/shoot ratios, specific root length, root density, mean number of roots tips and root length/leaf area ratio were determined in seedlings grown for 35 days inside growth chambers. All the species had low relative growth rates, low root/shoot ratios and low root densities (<0.5 cm/cm3). The species associated with disturbed habitats, in contrast to the species characteristic of undisturbed areas, presented small seeds, a dichotomous root branching pattern and large specific root length. No relationship was found between seed size and mean relative growth rate among the species studied.

Hummingbirds and Their Floral Resources in a Tropical Dry Forest in Mexico

We studied temporal and spatial relationships among hummingbirds and their food flowers in a tropical dry forest on the western coast of Mexico. From June 1985 to July 1986 we recorded flowering phenology, nectar production, and hummingbird visits to flowers, and made morphological measurements of hummingbirds and plants. Twenty-three species of plants were studied, and ten of them were pollinated exclusively by hummingbirds

Carbon Isotope Ratios of Plants of a Tropical Dry Forest in Mexico

Carbon isotope ratios were measured on leaves of the dominant species within a tropical dry forest in Mexico, which was characterized as being strongly drought deciduous. A variety of succulent epiphytes from diverse microsites had carbon isotope ratios indicating obligate crassulacean acid metabolism. All woody species examined had isotope ratios indicative of the C3 photosynthetic pathway, although there was a wide range of isotopic values. Two of the woody species that retained leaves during the dry season showed a large variation in carbon isotope ratios (up to 6 %o) that was dependent on microsite location. Key-words: Epiphytes, isotope ratios, crassulacean acid metabolism, water-use-efficiency, succulents