Banca de QUALIFICAÇÃO: ANDRESSA BÁRBARA SCABIN

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDRESSA BÁRBARA SCABIN
DATE: 27/01/2020
TIME: 13:00
LOCAL: Sala de reuniões - Decol
TITLE:

Half-empty Amazonia? Cascade effects of hunting induced defaunation in brazilian Amazonia 

KEY WORDS:

empty forest ; Amazon ; mammals ;birds;forest regeneration ;functional diversity ;carbon storage;

PAGES: 40
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Overhunting represents one of the greatest threats to wildlife worldwide and together with habitat loss and degradation has caused a sharp decline in mammal and bird populations in forests, a phenomenon known as defaunation. In general, the most intensely hunted species are involved in key processes in forest dynamics including pollination, dispersal, and predation of seeds and herbivory. Defaunation disrupts these ecological interactions essential for forest regeneration, which can critically compromise the maintenance of plant diversity and consequently the ecosystem services provided by the so-called “empty forests”. Since the 1990s, studies conducted in Neotropics, Africa, and Asia have investigated the effect of large vertebrate depletion on forest regeneration and so far, antagonistic effects have been found depending on which ecological interactions are most affected and the research methodology employed. This thesis aims to contribute to the debate by analysing the cascade effects of hunting-induced defaunation in the western Brazilian Amazon using a hunting pressure gradient that ranges from peri-urban forests to sites with low human densities in the Middle Juruá River region, Amazonas. The first chapter analyses the direct and indirect effects of hunting on the assemblage of mammals and birds. For this, we performed camera trapping in the understory and canopy using 20 cameras arranged in a grid system in 30 sampling units distributed on the hunting pressure gradient, which represented a total sampling effort of 22,005 cameras/night. We obtained 10,419 records belonging to 72 vertebrate species. Linear models were consistent in indicating hunting pressure as the main predictor of the accumulated biomass of game, terrestrial, arboreal, frugivorous-granivorous and small rodent species. These results indicate that the most intensely exploited areas present a markedly altered size structure both due to the decline of larger species and the increase in the abundance of small rodents, showing a possible mechanism of density compensation. The second chapter discusses the effect of the hunting gradient on dryland forest structure by analysing changes in the abundance ratio between young and adult tree species with different dispersal syndromes and discusses how changes in the representativeness of some functional traits in the community affect the. ecosystem services provision from more hunted forests. The terra firme tree community structure was accessed on 30 permanents 0.25-hectare plots in which 13,109 trees, trees, and palm trees were marked, measured and identified in 67 families, 275 genera and 876 species. The results indicate a tendency of decreasing abundance of young individuals of tree species dispersed by large vertebrates and increasing abundance of species of abiotic dispersion, which demonstrates that the heavily hunted areas already show evidence of a defaunation cascade effect on forest regeneration even in a continuous forest landscape where the great vertebrates were not completely extirpated. The third chapter, still under construction, aims to analyse whether these changes in plant structure reflect carbon storage in more intensively hunted forests. The carbon stock will be estimated and projected for the future based on dendrometric and wood density data collected in situ at the same hunting pressure gradient as the other chapters.

BANKING MEMBERS:
Interno - 1837921 - ALEXANDRE FADIGAS DE SOUZA
Presidente - 170.103.572-34 - CARLOS AUGUSTO DA SILVA PERES - NENHUMA
Interno - 1439088 - MAURO PICHORIM