Banca de DEFESA: KARLA VIEIRA MORATO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : KARLA VIEIRA MORATO
DATA : 10/02/2020
HORA: 10:00
LOCAL: IBIO sala 01
TÍTULO:

Influence of native forest cover and local vegetation structure on trophic interactions in shaded cocoa plantations in southern Bahia

PALAVRAS-CHAVES:

Atlantic forest. Cabruca. Forest cover. Herbivory. Top-down control. Anthropogenic changes.

PÁGINAS: 51
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
SUBÁREA: Ecologia Teórica
RESUMO:

In southern Bahia, a center of endemism, cacao is the most traded agricultural product and about 70% of production is made under the agroforestry system known as cabruca. This system reconciles cacao production with maintaining the original biodiversity. Although we know that arthropods can cause a reduction in annual cacao production, we do not know if changes in the abundance of predatory birds and arthropods, triggered by changes in the amount of forest in the landscape or the structural simplification of cacao crops due to increased intensity. Management through the removal of native vegetation and the use of agrochemicals to increase productivity can influence the local herbivory rate. Therefore, the objective of this study is to investigate the impact of the deforestation process and the simplification of vegetation structure on local herbivory patterns and to experimentally test whether these changes may be due to a relaxation of top-down control at a landscape scale in Atlantic Forest of southern Bahia State. This study was conducted on 18 goats on a forest cover gradient (3-66%), in which artificial caterpillar models were placed and observed for 4 days to verify the predation rate. We sampled understory birds and arthropods on cacao trees, and collected leaves to measure herbivory. Data were also collected from five local descriptors (vertical stratification, basal area, shading, abundance of native trees and cacao abundance). Statistical analysis was based on structural equation modeling and multiple linear regression. We reveal that predation pressure on herbivorous arthropods of cacao leaves, herein assessed by mold caterpillars, was mainly carried out by invertebrates and not by birds or other vertebrates. Such top-down control was further corroborated by the findings of our path analysis, in which the actual increasing abundance of herbivorous arthropods of cacao leaves local was not related with the local abundance of birds but rather, occurs as a response of a decreasing in the local abundance of predatory arthropods. Interesting, although predation rate of dummy caterpillars increased with deforestation while lessened under higher densities of cacao trees, we found no evidence that landscape or local features herein assessed influenced neither the actual invertebrate assemblages (predators or herbivorous) nor cacao leaf damage. Although we detected a trophic cascade involving invertebrates, i.e. predators controlling herbivorous, this interaction did not influence the actual amount of observed leaf damage in cacao trees. 

MEMBROS DA BANCA:
Presidente - 598.745.205-82 - DEBORAH MARIA DE FARIA - UNICAMP
Interno - 3062840 - BRUNO VILELA DE MORAES E SILVA
Externo à Instituição - RICARDO SIQUEIRA BOVENDORP - UESC