Canopy Herbivory and Insect Herbivore Diversity in a Dry Forest–Savanna Transition in Brazil

Abstract

This study aimed to compare canopy herbivore diversity and resultant insect damage to vegetation in two distinct and adjacent ecosystems, specifically a dry forest ecosystem and a cerrado (savanna) ecosystem that occur together in an abrupt transition zone in southeastern Brazil. In the dry forest, the canopy was reached using a single rope climbing technique, whereas the shorter canopy of the cerrado was assessed using a 7 m ladder. Insect specimens were collected by beating the foliage, and 20 representative leaves were collected to calculate the specific leaf mass (SLM) and leaf area loss through herbivory. Also, we collected ten soil samples from each habitat to determine soil nutrient content. We sampled 118 herbivorous insects from ten families, mostly in dry forest trees (96 individuals belonging to 31 species). A higher abundance of chewing and sap-sucking insects were observed in dry forest trees than in cerrado trees. The same pattern was observed for the richness of chewers, with a higher degree of diversity of chewers found in dry forest trees than in cerrado trees. Herbivorous insects were not affected by SLM regardless of guild and habitat. However, we observed a negative correlation between the herbivory rate and the specific leaf mass (SLM). The cerrado trees showed a higher SLM and lower herbivory rates than trees occurring in the dry forest. These results suggest that herbivory rates in the transition dry forest-cerrado may be driven by soil nutrient content, which is thought to influence leaf sclerophylly.Abstract in Portuguese is available at

Composition and Richness of Arboreal ants in Fragments of Brazilian Caatinga: Effects of Secondary Succession

“…In fragments of Atlantic Forest, for example, species richness may vary from 69 to 153 (Resende et al, 2013;Vasconcelos et al, 2014), whereas in areas of Brazilian savanna (Cerrado) species richness of arboreal ants ranges from 37 to 95 (Ribas et al, 2003;Frizzo et al, 2012). However, for Tropical Dry Forests areas, such as Caatinga, the number of arboreal ants sampled is generally low, ranging from 24 to a maximum of 43 species (Neves et al, 2010c;Neves et al, 2013;Silva et al, 2014), indicating that Caatinga environments, may naturally harbor a smaller ant richness when compared to other environments, probably due to habitat limitations such as drastic variation in resources and conditions during the season and between years (Quesada et al, 2009). Of all ant species sampled, seventeen were unique of the area of late succession, indicating that these species could be bioindicators of advanced stages of forest regeneration in Caatinga.…”

Trait distribution patterns in savanna and forest plant assemblages and their relationship with soil features

“…In addition to differences in disturbance frequency (Dantas et al 2013a) and light availability (higher in savannas than in forests), soil parameters are another important factor for these vegetation types. Soil features are suggested as one of the determinants of savanna-forest boundaries (Ruggiero et al 2002); while savannas are related to nutrient poor soils, forests usually occur in more fertile regions (Neves et al 2010). Differences in resource availability as well as disturbance frequency are expected to affect ecological strategies adopted by plants, reflected by trait values.…”

Distribution of insect galls in xeric and mesic habitats of Floresta Nacional de Silvânia, Brazil

“…In this context, the Cerrado constitutes a mosaic of phytophysiognomies, with many mesic (i.e., non-sclerophyllic and rich in water and nutrients) and xeric (i.e., sclerophyllic and poor in water and nutrients) vegetation types. These environmental diff erences between xeric and mesic habitats can directly aff ect the distribution of insect herbivores (Neves et al, 2010;Leal et al, 2015), such as the highly specialized gall-inducing insects (Araújo et al, 2014).…”