Article

Demographic threats to the sustainability of Brazil nut exploitation

Utrecht University, Utrecht, Utrecht, Netherlands
Science (Impact Factor: 31.48). 12/2003; 302(5653):2112-2114. DOI: 10.1126/science.1091698
Source: PubMed

ABSTRACT A comparative analysis of 23 populations of the Brazil nut tree (Bertholletia excelsa) across the Brazilian, Peruvian, and Bolivian Amazon shows that the history and intensity of Brazil nut exploitation are major determinants of population size structure. Populations subjected to persistent levels of harvest lack juvenile trees less than 60 centimeters in diameter at breast height; only populations with a history of either light or recent exploitation contain large numbers of juvenile trees. A harvesting model confirms that intensive exploitation levels over the past century are such that juvenile recruitment is insufficient to maintain populations over the long term. Without management, intensively harvested populations will succumb to a process of senescence and demographic collapse, threatening this cornerstone of the Amazonian extractive economy.

Download full-text

Full-text

Available from: Rogério Gribel, Jun 19, 2015
0 Followers
 · 
232 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effects of the present biodiversity crisis have been largely focused on the loss of species. However, a missed component of biodiversity loss that often accompanies or even precedes species disappearance is the extinction of ecological interactions. Here, we propose a novel model that (i) relates the diversity of both species and interactions along a gradient of environmental deterioration and (ii) explores how the rate of loss of ecological functions, and consequently of ecosystem services, can be accelerated or restrained depending on how the rate of species loss covaries with the rate of interactions loss. We find that the loss of species and interactions are decoupled, such that ecological interactions are often lost at a higher rate. This implies that the loss of ecological interactions may occur well before species disappearance, affecting species functionality and ecosystems services at a faster rate than species extinctions. We provide a number of empirical case studies illustrating these points. Our approach emphasizes the importance of focusing on species interactions as the major biodiversity component from which the ‘health’ of ecosystems depends.
    Functional Ecology 11/2014; 29(3). DOI:10.1111/1365-2435.12356 · 4.86 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Revisiting Camu-camu (Myrciaria dubia): Twenty-seven Years of Fruit Collection and Flooding at an Oxbow Lake in Peruvian Amazonia Camu-camu (Myrciaria dubia HBK McVaugh; Myrtaceae) is an important riparian species in the floodplain forests of Peruvian Amazonia, and its fruits have been harvested commercially for over 30 years. We examined the population impacts of intensive fruit collection on this species by remeasuring a 1,000 m 2 inventory transect that was established in 1984 in a dense stand of M. dubia along an oxbow lake. We found that regeneration rates had declined notably since the original survey, and that the number of M. dubia individuals had dropped from 693 to 161 genets. While this dramatic shift in population structure would appear to be caused by excessive fruit collection, the same decline in regeneration was noted for Eugenia inundata DC, an associated species of similar growth form and phenology that is not harvested. The life cycles of both species are closely tied to the rise and fall of the river. In addition to annual fruit collection, we suggest that the extreme hydrological events that have occurred in the Amazon Basin over the last few decades, as well as the successional development of the ox-box lake study site that has been slowly filling up with sediment, also play a role in the observed reduction in M. dubia numbers. Revisitando camu-camu (Myrciaria dubia): Veinte y siete años de la recolección de frutos y la inundación en una cocha en la Amazonía peruana Camu-camu (Myrciaria dubia HBK McVaugh; Myrtaceae
    Economic Botany 04/2014; 68(2):169-176. DOI:10.1007/s12231-014-9269-4 · 0.77 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Seven polymorphic microsatellite markers were developed and validated for Bertholletia excelsa (Brazil nut tree) population genetic studies. This species is a widespread monotypic Amazonian tree with high non-timber economic value. Unfortunately, Brazil nut production is currently less than 25% of historical production levels, because of extensive deforestation. All pairs of primers produced clearly interpretable and polymorphic bands. No linkage disequilibrium was observed in an analysis of 46 individuals from one population, three to seven alleles per locus were observed; the expected heterozygosity ranged from 0.378 to 0.978, with significant heterozygote excess for four loci. An analysis of individuals from two populations showed private alleles at all loci. These primer pairs will be useful for population studies, especially for comparing samples from different parts of the Amazon forest.
    Genetics and molecular research: GMR 01/2013; 12(4):5278-82. DOI:10.4238/2013.November.7.2 · 0.85 Impact Factor