Torbjørn Haugaasen

Nutty livelihoods: efforts to save rural incomes and a crucial extractive industry in the Amazon (BRAZIL)

Brazil nut tree

The Brazil nut tree (Bertholletia excelsa) is a long-lived and widespread emergent tree in lowland Amazonian forests and provides one of the most socio-economically important non-timber tropical forest products – the Brazil nut. However, despite its economic importance we know relatively little about the ecology and biology of this species under natural conditions and the impacts of human exploitation on population dynamics and recruitment. This project addresses a number of these questions using a combination of direct observations, field experiments and laboratory analysis.

Investigating the underlying mechanisms of the population dynamics will help determine the impact of exploitation on the maintenance of Brazil nut populations throughout Amazonia, and the sustainable harvest of Brazil nuts in the future. A management plan to deal with Brazil nut exploitation is sorely needed and this study will go a long way to provide the answers needed to draft such a plan and ultimately inform the sustainable harvest of Brazil nuts throughout Amazonia.

Major aims of this study therefore include:
a) Investigate in detail the current demographic status of the Uauaçú Brazil nut population.
b) Gain information to better inform landscape-level management options for the sustainable harvest of Brazil nuts.

To achieve this we will, amongst other things, gather basic demographic data such as the distribution and sizes of adult trees and seedlings, run seed dispersal experiments and carry out genetic analyses. The study will take place at Lago Uauaçú (a large crescent-shaped black-water lake) which is located in the lower Rio Purús region of central-western Brazilian Amazonia, about 350 km southwest of Manaus. The Uauaçú area presents a unique place in which to study Brazil nuts on a large scale as it contains a mosaic of natural Brazil nut stands of varying harvest histories.

For more information contact T.Haugaasen@uea.ac.uk or go to www.tropicalforestresearch.org/People/thaugaasen.aspx

Project Update: April 2008

Seed station with marked seeds

During the last few months we have completed several components of our research. We have mapped around 1200 Brazil nut trees from six Brazil nut stands in our study area. The stands have a density of 1.7-3.6 Brazil nut trees per hectare and the majority of trees in the sample are of intermediate sizes, particularly falling in the categories 100-150 cm in diameter at breast height. Careful searches for small trees and seedlings have only yielded two saplings in the 13 hectares of primary forest currently searched. However, similar searches in secondary forest found seedlings to be very abundant and seedlings also appear to be highly abundant along existing forest trails used by Brazil nut collectors. Seed dispersal experiments demonstrated that the agouti (Dasyprocta sp.) is an efficient disperser of Brazil nuts, scatter-hoarding them up to 50m from the seed stations. However, agoutis were also extremely efficient at later locating their hidden seeds. Resource use varied between seasons as seeds were removed quicker and more were eaten immediately during experiments outside the Brazil nut season – a time of general food shortage in the forest. Another experiment using individually marked fruits showed that agoutis could carry entire fruits more than 50m from the parent tree.