Relationship between tree size and insect assemblages associated with Anadenanthera macrocarpa

Abstract

This study analyzed the effects of tree size, and correlated architectural tree characteristics, on the assemblages of ants and insect herbivores associated with Anadenanthera macrocarpa (Mimosaceae). The latter is a myrmecophilous tree species from the Atlantic rainforest in south‐eastern Brazil. Ants and insect herbivores were collected in 30 individuals of A. macrocarpa, ranging from young individuals (>3 m in height) to emergent trees (up to 40 m). Tree height was a strong indicator of other tree characteristics, including trunk diameter, crown height, crown volume, and number of bifurcations. Ants were collected using arboreal pitfall traps and beating, while insect herbivores with beating only. There was a significant increase in both abundance and species richness of ants and insect herbivores with an increase in tree height. In addition, tree height had a significant effect on the species composition of ants and insect herbivores. Assemblages of both taxa showed a nested organization pattern. The species found in small‐ and medium‐sized trees, in general, consisted of a subset of the species found in the crowns and branches of larger, canopy or emergent trees. Thus, in A. macrocarpa, there was not a replacement of insect species with plant ontogeny. This finding is at variance with those conducted in tropical evergreen forests and which show a clear stratification between the understory and canopy insect faunas. Additional studies are needed to explain these contrasting patterns, but it is possible that differences in microclimate are involved. As the forest we studied is semi‐deciduous, microclimatic gradients between the understory and the canopy habitat are probably less severe than in an evergreen forest, thus resulting in a lower turnover of species.

Estratificação vertical de formigas em cerrado strictu sensu no Parque Estadual da Serra de Caldas Novas, Goiás, Brasil

“…Por outro lado, para o presente trabalho, as espécies de formigas mais freqüentes foram registradas tanto no solo quanto na vegetação, indicando que, diferentemente das florestas tropicais (BRÜHL et al, 1998) Em relação à sobreposição de espécies entre o estrato arbustivo e arbóreo, ficou claramente demonstrado que a mirmecofauna do estrato arbustivo nada mais é do que um subconjunto do estrato arbóreo (CAMPOS et al, 2006). De fato, apenas quatro das 16 espécies do estrato arbustivo não ocorreram no estrato arbóreo.…”

Contrasting effects of sampling scale on insect herbivores distribution in response to canopy structure

“…Study area: Samples were taken in three forest sites within the Rio Doce Park, the largest continuous preserved forest (35 974ha) in Minas Gerais State,'' W) (Campos et al 2006a). The Park is located within the domain of Atlantic Forest, one of the World's biodiversity hotspots, under urgent need of data to support conservation actions (Myers et al 2000).…”

“…On a more local, hereafter fine, scale, as within individual tree crowns, resource quality and availability, as well as microclimate oscillations could be more important for insect distribution, based on specific interactions (Hunter et al 1997, Campos et al 2006a. Hence, various plant traits might affect distribution of associated herbivores, such as chemical and physical defenses, plant tissues water/nutrient contents (Rossi & Stiling 1998), phenological variation in growth rate, leaf, flower and fruit production (Rehill & Schultz 2002), and plant architecture (Lawton 1983, Denno & Roderick 1991, Alonso & Herrera 1996, Espírito-Santo et al 2007.…”

Oak canopy arthropod communities: which factors shape its structure?

“…In addition, during the rainy season, the young leaves are the most abundant and nutritious, they are less hard and have less chemical defenses (Kursar and Coley 2003;Boege 2004;Coley et al 2006). Finally, the increase of vegetation in the forests (i.e., annual vegetation) during the rainy season can serve as a bridge so that new species of arthropods have a greater chance of colonizing new trees (Basset et al 1992;Campos et al 2006).…”