We compared the species diversity of copronecrophagous beetles (Scarabaeinae), bats, and frogs in tropical montane cloud forest (original vegetation) and shaded coffee plantations (an agroecosystem common to the region) for a landscape in central Veracruz, Mexico. We sampled in three tropical montane cloud forest fragments and in three coffee plantations with traditional polyculture shade between 1998 and 2001. The three indicator groups responded differently to the transformation of tropical montane cloud forest into shaded coffee plantations. The species richness of frogs was one-fifth less in coffee plantations than in forest fragments, and only one-third of the frog species occurred in both forest fragments and coffee plantations. The number of beetle species and their abundance was significantly greater in coffee plantations than in the forest fragments, whereas species richness and species composition of bats were virtually the same in both habitats. The majority of the abundant species remained as such in both communities, but species that were less abundant were not scarce in both habitats. We attributed differences in the species assemblages to the differing degrees of penetrability of the borders of the two habitat types (especially for the coffee plantations) and to the differences in life-history traits among species. Shaded coffee plantations form a matrix that envelops the remaining fragments of cloud forest. Together they connect the forest fragments with the other habitats of the landscape and represent a highly functional resource for the preservation of biodiversity that serves as a complement to but not a substitute for cloud forest in this notably modified landscape. Key Words: indicator groups, Mexico, shaded coffee plantations, tropical montane cloud forest Diversidad de Ranas, Murciélagos y Escarabajos del Estiércol en el Bosque de Niebla y Agrosistemas de Café en Veracruz, México Resumen: Comparamos la diversidad de especies de escarabajos copronecrófagos (Scarabaeinae), murciélagos y ranas en bosque tropical montano nublado (vegetación original) y en plantaciones de café de sombra (un agrosistema común en la región) en un paisaje en el centro de Veracruz, México. Entre 1998 y 2001 muestreamos en tres fragmentos de bosque tropical montano nublado y en tres plantaciones de café con sombra de policultivo tradicional. Los tres grupos indicadores tuvieron diferente respuesta a la transformación de bosque tropical montano nublado en plantaciones de café de sombra. La riqueza de especies de ranas fue una quinta parte menor en las plantaciones de café que en los fragmentos de bosque, y solo la tercera parte de las especies de ranas ocurrieron tanto en los fragmentos de bosque como en las plantaciones de café. El número de especies de escarabajos y su abundancia fue significativamente mayor en las plantaciones de ‡Current address: 6 Suffolk Walk, Pineda et al. Habitat Transformation and Species Diversity 401 café que en los fragmentos de bosque, mientras que la riqueza y composición de especies de...

The objective of this study is to evaluate the effect of environmental (associated with the expansion of cattle ranching) and biogeographical factors on the diversity of dung beetle (Scarabaeinae) assemblages along three altitudinal gradients in the Neotropical region. One gradient is located in the Mexican Transition Zone, on the Cofre de Perote mountain, the other two are in the northern Andes (the Chiles Volcano and the Río Cusiana Basin). For the three gradients, the number of species decreased as altitude increased. On the Cofre de Perote, regardless of altitude, the number of species and of individuals was similar in both forest and pasture, while species composition was different between habitats. On this mountain, species turnover in pastures was characterized by the addition of new species as altitude increased. In the northern Andes, species diversity was always greater in the forest than in the pasture, and species turnover between habitats was notably influenced by species loss with increasing altitude. As such the pasture fauna of the northern Andes was an impoverished derivative of the fauna present in the forests at the same altitude characterized by species of Neotropical affinity with a limited capacity for colonizing open, sunnier habitats. The opposite occurs in the areas used by cattle on the Cofre de Perote. This habitat has its own fauna, which is mainly comprised of Holarctic and Afrotropical species adapted to the prevailing environmental conditions of areas lacking arboreal vegetation. These results suggest that the impact on beetle communities caused by human activities can differ depending on the geographic position of each mountain and, particularly, the biogeographical history of the species assemblage that lives there.A decrease in species richness and changes in the composition of the flora and fauna with increasing altitude have frequently been described in the literature (Huston 1994). However, it is not possible to describe a general relationship between changes in diversity and increasing altitude (Rahbek 1995), because the ecological factors (current environmental conditions, e.g. land use) and biogeographical factors differ in their relative effect depending on the mountain system being studied (Brown 2001). This is emphasized by the fact that we still do not understand how these factors vary and interact as altitude changes. For this reason comparative studies using the same taxonomic group along altitudinal gradients on different mountains (such as this one), and those that use several taxonomic groups along the same altitudinal gradient of the same mountain are very useful for explaining this co-variation (Lomolino 2001).Studying the altitudinal variation in dung beetle assemblages on different mountains around the world, Lobo and Halffter (2000) proposed two different biological and interrelated processes to explain the conformation of the biota on mountains, the patterns of species richness and variations in composition: horizontal colonization by elements originating fro...

Abstract1. As tropical cattle ranching continues to expand, successful conservation will require an improved understanding of the relative impacts of different livestock systems and landscape structure on biodiversity. Here, we provide the first empirical and multi-scale assessment of the relative effects of livestock intensification and landscape structure on biodiversity in the threatened tropical dry forests of Mesoamerica.2. We used a dataset of dung beetles (169,372 individuals from 33 species) collected from 20 1-km 2 landscapes, ranging from zero-yielding forest sites to high-yield cattle ranches and maize farms, to investigate the relative effect of livestock intensification (net cattle production; macrocyclic lactone use; annual dung production) and landscape structure (landscape composition and configuration) at multiple spatial scales on different attributes of dung beetle communities using a multi-model averaging approach.3. Dung beetle species richness, biomass and composition were more strongly related to landscape structure than to livestock intensification.4. Forest cover was the best predictor of dung beetle assemblages, being positively related to species diversity and biomass across multiple spatial scales. The use of macrocyclic lactones was strong and negatively related to dung beetle communities at the local scale. Synthesis and applications:Maximising forest protection through a "land sparing" strategy is likely to be the best strategy for reducing negative impacts of cattle farming on Neotropical dung beetle communities. However, increasing or maintaining yields while reducing agrochemical inputs will be important for conserving onfarm biodiversity and the ecosystem services that dung beetles provide in livestock-dominated landscapes. K E Y W O R D Scattle ranching, dung beetles, food production, forest protection, land sparing, livestockdominated landscapes, spatial heterogeneity, species richness, tropical biodiversity, tropical dry forest

No abstract

No abstract