COELHO, MS.; BELMIRO, MS.; SANTOS, JC. e FERNANDES, GW. Herbivory among habitats on the Neotropical tree Cnidoscolus quercifolius Pohl. in a seasonally deciduous forest. Braz. J. Biol. [online]. 2012, vol.72, n.3, pp.453-457.
ISSN 1519-6984. http://dx.doi.org/10.1590/S1519-69842012000300006.
Does habitat modulate herbivory patterns in tropical dry forest trees?
Through out the field course Ecologia da Caatinga offered by the Universidade Federal de Pernambuco conducted at Parnamirim town in April, 2010 was carried a research focus on the herbivory patterns of a Tropical Dry Forest tree Cnidoscolus quercifolius Polhem. Many hypotheses intend to explain how the herbivore activities are spatially distributed through out ecosystems. One of the most well known is the harsh environment hypothesis witch explain how the herbivore activities is distributed across moisture gradients. As expected, the hypothesis predictions will vary with the insect guild. For instance, free feeding insects will respond differently than the endophytic insects. The first ones are more susceptible to the moisture stress than the last ones.
Tropical Wet Forests host a complex plant structure and composition. The herbivorous distribution across Tropical Wet Forests was already well studied. On the other hand, Tropical Dry Forests host an opened canopy and a lesser complex structure and composition compared to Tropical Wet Forests. However, information about how the vegetation features of Tropical Dry Forests affect the herbivorous spatial distribution is still lacking. The aim of our study was to describe herbivory patterns in C. quercifolius in four different habitats and test the hypothesis that individuals of C. quercifolius suffer different herbivory rates according to the habitat in consequence of hydrothermal stress.
Four different habitats were sampled 1) forest edge, (2) mesic (near to the perennial water source), (3) forest interior, (4) rupestrian (rupestrian outcrop) witch represent different moisture levels. Leaves from four different habitats were collected and the abundance of galls (endophytic insects) and the leaf losses by chewing insects were recorded.
We found important differences in the herbivory rates among habitats indicating that the herbivores are heterogeneously distributed despite the simpler structure and composition of Tropical Dry Forests. We also discuss the possible mechanisms behind the results found.
This paper was part of the scientific activities conducted during the course Ecologia da Caatinga witch was supported by Procad/Capes 0166-01, international cooperation program 002/09 and FAPEMIG.
Marcel Serra Coelho