Evaluation of the experimental exclusion of vertebrates on the decomposition of three species of plants under different land uses in the state park serra do mar- nucleus Santa Virgínia

Author(s)

Gabriela Garcia Medeiros

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2016-07-11

Examining board members

Luiz Antonio Martinelli; Luciana Ferreira Alves; Pedro Henrique Santin Brancalion

• Advisor: Luiz Antonio Martinelli

Abstract

The diversity of Atlantic forest is constantly threatened due to habitat loss caused by the destruction and alteration of natural environments, and most of the biome is now in small and fragmented areas. This fact is of a great concern, because the remaining areas in Atlantic forest are in small highly disturbed fragments, resulting in loss of biodiversity of the existing fauna, like mammals and birds. Many studies have shown that specialist mammals and birds (e.g. insectivores) are very sensitive to environment fragmentation and tend to disappear in open areas. The loss of these animals is likely to cause an increase in the density of arthropods and rates of herbivory, causing a top-down effect that may even influence the cycling of nutrients. We aimed to investigate how decomposition rates are modified by the experimental exclusion of vertebrates in an area with different land coverage in the Atlantic forest. Vertebrate exclusion plots and control plots were allocated in areas with different land coverage (pasture and forest) to evaluate the top-down effects in decomposition. We used three different kinds of leaves, being one grass (Brachiaria decumbens), one very common primary specie of the area (Tibouchina sellowiana) and a mix of primary forest leaves. Litterbags were used to evaluate the decomposition rate and it was collected during intervals of 16, 36, 71, 181 and 247 days. The vegetal residue was cleaned, dried and weighted to obtain the remaining mass (%) and decomposition rate, after that, the material was milled and weighted in subsamples for analyses of nutritional quality (N, C, P, lignin, cellulose and polyphenols). The decomposition rate was not different for the control and vertebrate exclusion plots, as a result, it was not possible to show the top-down effect in decomposition, possibly because of the high soil biodiversity in the area where the experiment was done. It would be very important to remake this experiment in a smaller and more disconnected area, in order to show how this cascade effect occur in Atlantic forest´s smaller fragments. Furthermore, the decomposition was faster at the forest plots than at the pastureland plots and the grass leaf litter presented the higher decomposition rate than the primary forest leaves and T. sellowiana and it was possibly caused by the interaction between nitrogen, lignin and C:N ratio. (AU)

• FAPESP's process: 14/01245-0 - Evaluation of the experimental exclusion of insectivores vertebrates on the decomposition of three species of plants under diferents land uses in the State Park Serra do Mar, nucleus Santa Virginia
• Grantee: Gabriela Garcia Medeiros
• Support Opportunities: Scholarships in Brazil - Master