03128naa a2200373 a 450000100080000000500110000800800410001902200140006010000220007424501200009626000090021652019770022565000160220265000250221865000250224365000250226865000220229365300090231565300240232465300220234865300230237065300270239365300270242065300280244765300270247565300270250265300200252965300280254965300240257765300260260170000180262770000260264577300830267115063262021-07-28       2005    bl uuuu     u00u1 u    #d  a0378-11271 aWADT, L. H. de O.  aPopulation structure and nut yield of a Bertholletia excelsa stand in southwestern Amazonia.h[electronic resource]  c2005  aAlthough Brazil nut (B. excelsa) is often touted as one of the most economically successful NTFPs, little is known about the population structure of this species within its natural range in Southwestern Amazonia or ecological factors that affect fruit production. Since these are considered fundamental for sustainable resource management, we examined a natural Brazil nut stand in an extractive reserve in Acre, Brazil, posing the following questions: (1) What is the spatial distribution, species density, and size 'class structure of B. excelsa' and (2) What tree-level factors influence Brazil nut production? In a 420 ha census, 568 trees - 10 cm diameter at breast height (dbh) were counted, resulting in a density of 1.35 trees ha-1. Based on the nearest-neighbor method, an index of aggregation (R) of 0.77 indicated a rejection of the null hypothesis of a strictly random distribution pattern. Yet, this value suggests a much greater tendency toward randomness than either clumping or uniformity. Our data do not show the commonly reported existence of groves, referring to clearly defined clusters of 50 to several hundred trees separated from similar clusters by great distances. Almost 1/4 of the population (23%) was composed of non-reproductive juveniles. Maximum R2 improvement analysis applied to four distinct diameter classes provided insight into the dynamics of production-related variables over the species life cycle. While dbh explained 1/3 of production variance (R2 = 0.3360) in the smallest diameter class (10 cm - dbh &lt 50 cm), which included those in the process of reaching reproductive maturity, crown form best explained production variance of very large trees (dbh - 100 cm). Results also demonstrated a significant negative correlation between crown vine load and production of trees ? 50 cm dbh (r = -0.13, P = 0.008), suggesting the need for further study on vine cutting as a possible silvicultural treatment for enhancing nut yields.  aBrazil nuts  aPopulation structure  aSpatial distribution  aBertholletia excelsa  aCastanha do pará  aAcre  aAmazônia Ocidental  aAmazonia Suroeste  aCastanha-do-brasil  aDensidade de espécies  aDistribución espacial  aDistribuição espacial  aEstructura poblacional  aEstrutura populacional  aNuez del Brasil  aRESEX Chico Mendes (AC)  aSouthwestern Amazon  aSudoeste da Amazônia1 aKAINER, K. A.1 aGOMES-SILVA, D. A. P.  tForest Ecology and Management, Amsterdamgv. 211, n. 3, p. 371-384, June 2005.