Demographic threats to the sustainability of Brazil nut exploitation     

Peres CA  Baider C  Zuidema PA  Wadt LH  Kainer KA  Gomes-Silva DA  Salomão RP  Simões LL  Franciosi ER  Cornejo Valverde F  Gribel R  Shepard GH  Kanashiro M  Coventry P  Yu DW  Watkinson AR  Freckleton RP 《Science (New York, N.Y.)》2003,302(5653):2112-2114

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.  相似文献