Both decreases in compositional similarity with increasing geographic distances between sites (i.e. distance–decay relationship) and vertical stratification of species composition are key issues in ecology. However, the intersection between these two trends has scarcely been investigated. Here we use identical sampling methods in the canopy and at ground level in a tropical rainforest remnant on the coast of the Gulf of Mexico to evaluate, for the first time, a distance–decay relationship within vertical strata in insect assemblages. We found that the ant assemblage was vertically stratified; ant species richness was higher at ground level than in the canopy, and the species composition differed between the two vertical strata. Moreover, we observed that β-diversity increased with geographic distance at ground level, but not in the canopy strata. However, contrary to our prediction, there was less species turnover (lower β-diversity) between vertical strata than between trees. These findings may reflect differences in the dispersal capacity and nest habit of ants from each vertical stratum, and also habitat heterogeneity on the horizontal scale, e.g. the species of sampled trees. Our results illustrate the importance of sampling more than one vertical stratum to understand the spatial distribution patterns of biological diversity in tropical rainforests.

Choosing an appropriate sampling method to study ants is a key factor since distinct sampling methods can capture distinct ant fauna and, therefore, leading to bias in the interpretation and conclusion of the patterns observed. Despite it is well known that the ant fauna is vertically stratified, some of the sampling methods cannot be used throughout the whole vertical stratum (e.g., fogging and Winkler extractor). Here we compared the complementarity of hand collecting and baiting (with tuna or honey) in ant surveys focused on the stratification of the ant fauna in a tropical rainforest in Mexico. We found a total of 44 ant species, belonging to 17 genera and five subfamilies. The three sampling methods were clearly complementary at both the forest floor and canopy levels, even with as little as 10 minutes of search time for hand collecting. The ant species composition differed among sampling methods at both vertical strata. Hand collecting yielded higher ant species richness and more exclusive species than either bait at both vertical strata, but both tuna and honey baits also led to the detection of some (though fewer) exclusive ant species. The combination of hand collecting, tuna, and honey baits should thus be considered complementary tools for ant inventories, since using the two methods together yielded more complete inventories at both vertical strata. An additional advantage is that both methods can be used in both strata, ensuring that data in different vertical strata are comparable and allowing more reliable comparisons among these different habitats.

2020) Diversidad y conservación de anfibios y reptiles en un área protegida privada de una región altamente transformada en el sur de Veracruz, México. Acta Zoológica Mexicana (nueva serie), 36, 1-14. https://doi.org/10.21829/azm.2020.3612164 RESUMEN. El establecimiento de Áreas Protegidas Privadas (APPs) es una de las estrategias para la protección de la biodiversidad ante la modificación del hábitat en bosques tropicales; sin embargo, su importancia en conservación ha sido poco evaluada. En este trabajo estimamos la importancia de un APP conocida como Área de Protección y Desarrollo de Ceratozamia (APDC) para la conservación de anfibios y reptiles, en comparación con otras dos APPs (Parque Ecológico Jaguaroundi y el Parque Ecológico Tuzandepetl) en el sur de Veracruz, México. El APDC tiene una extensión de 100 hectáreas: 50 ha de bosque tropical subcaducifolio y 50 ha de pastizal. Los muestreos para este estudio se realizaron entre los años 2015 y 2016, empleando el método de búsqueda libre restringida por tiempo (esfuerzo de muestreo total = 768 horas-persona). En total, en el APDC se registraron 20 especies de anfibios y 35 de reptiles. El 20% de los anfibios y el 32% de reptiles registrados se encuentran en alguna categoría de riesgo de extinción según la Norma Oficial Mexicana NOM-059-SEMARNAT-2010, dos especies de anfibios y una especie de reptil están incluidas en la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza (UICN), mientras que el 12% de los reptiles se encuentran en categoría de vulnerabilidad ambiental alta. El APDC tuvo la mayor riqueza de especies en comparación con las otras dos APPs. Los anfibios tuvieron una composición relativamente similar entre las APPs, mientras que para los reptiles la composición de especies tendió a ser distinta. Nuestros resultados indican que por la riqueza de especies y el número de especies amenazadas de extinción y de especies no evaluadas por la UICN que alberga, el APDC contribuye a la conservación de herpetozoos en una zona altamente transformada del sur de México, en conjunto con las otras dos APPs, donde el Área Natural Protegida bajo régimen gubernamental más cercana (Reserva de la Biosfera Los Tuxtlas) se localiza a 50 km.

Tropical forests are home to a rich biodiversity, and protected natural areas (PNA) represent one of the approaches adopted for conserving this biodiversity. However, PNAs are under constant threat of becoming too isolated in a landscape matrix frequently hostile to most of the species they harbor. A new system of conservation has recently been proposed in the form of areas under private protection (privately protected areas or PPAs) that complement the existing PNAs in their task of conservation. The objective of this study was to document the richness of mammal species that inhabit a 100 ha fragment of rain forest and pasture decreed as a PPA in southeastern Veracruz, Mexico, and to compare it to two nearby PPAs and one PNA of contrasting conservation values. Mammals were monitored in the three climatic seasons of the year through direct observation, track identification, and the use of Tomahawk, Sherman, and camera traps, as well as mist nets. We recorded 32 mammal species-including seven threatened species-belonging to 28 genera and 15 families. These results are important considering that 29 and 14 species have been reported for two other PPAs in the region that are 10 times larger. However, large mammals of the Orders Carnivora, Artyodactyla, and Perissodactyla were absent and are probably locally extinct. We propose that, under specific favorable conditions, forested PPAs can make an important contribution to strategies designed for biodiversity conservation in tropical ecosystems, by helping to conserve endangered species of both medium-and smallsized mammals.

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