Hormigas: relaciones especies-área en fragmentos de bosque seco tropical

Abstract

-We analyzed the effect of fragmentation on ant species-area and specimen frequencyarea relationships in nine patches of tropical dry forest in the middle Cauca river basin in Colombia. Species richness and specimen relative frequency of ants were positively correlated with area, whereas no signifi cant correlation was found between species richness and the degree of isolation calculated for the forest patches. As the fragmentation affects different functional groups in different ways, we analyzed the species-area relationship for separate functional groups of ants. According to the habitat requirements we found that the species richness increased faster as area increased for ants inhabiting decomposing wood, followed by ants associated with trees, while species richness of ants living under dead leaves did not correlate with area. According to the food preference, species richness was positively correlated with area for the army ant group, while no signifi cant correlation was found for solitary hunters or for leaf-cutting ants. Ant species richness and specimen density were calculated from equal size samples and examined in relation to the habitat area. An inverse correlation was found only for specimen density, the opposite of what was expected. To our knowledge this is one of the fi rst studies showing differential responses of functional groups of ants to habitat loss. Moreover, it emphasizes the conservation value of small forest fragments for ants in a tropical dry forest.KEY WORDS: Formicidae, fragmentation, isolation, species richness, functional group RESUMEN -Analizamos el efecto de la fragmentación sobre las relaciones especies-área y frecuencia relativa-área de hormigas en nueve fragmentos de bosque seco tropical en la cuenca media del río Cauca, Colombia. La riqueza y frecuencia relativa total de hormigas se correlacionó positivamente con el área más no con el grado de aislamiento. Como la fragmentación afecta diferencialmente grupos funcionales, se encontró que según el hábitat que ocupan son más afectadas en su orden las especies que viven en troncos en descomposición y la vegetación arbórea, mientras que las especies de hormigas asociadas a la hojarasca, no mostraron relación signifi cativa con el área. Según las preferencias en la obtención de alimento, las especies cazadoras en grupo, mostraron correlación con el área de los fragmentos, mientras que hormigas cazadoras solitarias y cultivadoras de hongos, no se correlacionaron signifi cativamente. En contraste a lo esperado, la densidad de individuos y especies de hormigas, basadas en muestras de igual tamaño, fueron relacionadas con el área, encontrando una relación no signifi cativa para la densidad de especies y una correlación inversa signifi cativa para la densidad de individuos. Según nuestro conocimiento, este es uno de los primeros estudios que muestra respuestas diferenciales de grupos funcionales de hormigas a la pérdida del área, además que se enfatiza el gran valor de los pequeños fragmentos para la conservación de la diver...

Do leaf‐cutting ants benefit from forest fragmentation? Insights from community and species‐specific responses in a fragmented dry forest

“…Biodiversity loss is the best known consequence of habitat loss in fragmented systems (Watling & Donnelly, ), a trend that has also been reported for some general ant communities (Vasconcelos et al ., ), but had yet to be assessed for LCA. In our study, LCA richness did not change with fragment area, as observed in fungus cultivating ants (Lozano‐Zambrano et al ., ). As generalists tend to be less vulnerable to habitat loss (e.g.…”

“…We recorded five LCA species, all within Acromyrmex , a genus particularly rich in subtropical and southern South America (Fowler & Claver, ). Leaf‐cutting ant communities appear to be relatively rich in the Chaco Serrano forest, in comparison with only two (Sobrinho et al ., ; Wirth et al ., ; Lozano‐Zambrano et al ., ; Meyer et al ., ; Leal et al ., ) or three species (Ribas et al ., ; Dohm et al ., ), mostly in the genus Atta , recorded from comparable studies carried out in fragmented tropical forests. This difference might be related to the greater diversity of the genus Acromyrmex in comparison with Atta (Fowler & Claver, ).…”

“…As generalists tend to be less vulnerable to habitat loss (e.g. Cagnolo et al ., ), the wide plant range used by LCA species, as well as their preference for pioneer plant species (Farji‐Brener, ) which are frequent in smaller fragments (Lozano‐Zambrano et al ., ), may contribute to weaken the expected area effects on species richness. Nonetheless, forest area influenced LCA overall abundance interacting with edge effects, so that fewer LCA nests were found in smaller fragments, albeit only at the forest interior.…”

Ant community patterns in highly fragmented Chaco forests of central Argentina

“…; Lozano‐Zambrano et al . ) and others showing a relationship between richness and distance to the forest (Perfecto & Vandermeer ). The new boundaries between fragments and crop matrices could change microenvironmental conditions and enhance or limit ant persistence, depending on the biology of the species (Crist ; Brandão et al .…”

Effects of the Heterogeneity of the Landscape and the Abundance ofWasmannia auropunctataon Ground Ant Assemblages in a Colombian Tropical Dry Forest

“…Moreover, the richest forests have a greater number of rare species [31], and the richness and relative frequency of some groups (e.g., legionary or army ants) are correlated positively with the area [32]. Although the actual composition of ant species varies significantly among sampling sites [33], the little fire ant (Wasmannia auropunctata R.) is numerically dominant; thus, it has been proposed as an indicator of low diversity in the dry forest [34].…”