Population structure and nut yield of a Bertholletia excelsa stand in Southwestern Amazonia |
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| Institution: | 1. Centro de Pesquisa Agroflorestal do Acre (Embrapa Acre), Caixa Postal 321, Rio Branco, Acre 69901-108, Brazil;2. University of Florida, School of Forest Resources and Conservation and the Tropical Conservation and Development Program, P.O. Box 110410, Gainesville, FL 32611-0410, USA;3. Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Rua Palmas, 96, Jardim Tropical, Rio Branco, Acre 69.910-560 Brazil;1. College of Textiles, Donghua University, Shanghai, 201620, PR China;2. Key Laboratory of Textile Science and Technology, Ministry of Education, College of Textiles, Donghua University, Shanghai, 201620, China;3. State Key Laboratory for Modification of Chemical Fibers and Polymer Material, College of Materials Science and Engineering, Donghua University, Shanghai, 201620, China;1. Institute of Ecology and Key Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China;2. High Meadows Environmental Institute, Princeton University, Princeton, NJ 08544, USA;3. Ministry of Education Key Laboratory of Earth Ecosystem Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China;1. Instituto de Ecología, A.C. (INECOL), Carretera Antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz 91070, Mexico;1. Department of Biochemistry and Molecular Biology, Natural and Exact Sciences Centers, Federal University of Santa Maria, Santa Maria, Brazil;2. Clinical Laboratory Analysis, University Hospital, Federal University of Santa Maria, Santa Maria, Brazil;3. Department of Nutrition, Center Franciscan University, Santa Maria, Brazil;4. Lutheran University of Brazil, Santa Maria, Brazil;5. Department of Technology and Food and Science, Federal University of Santa Maria, Santa Maria, Brazil;6. Department of Industrial Pharmacy, Federal University of Santa Maria, Santa Maria, Brazil;1. Laboratoire de Mécanique Appliquée des Nouveaux Matériaux (LMANM), Université 8 Mai 1945 Guelma, B.P.401, Guelma 24000, Algeria;2. Université des frères Mentouri, Constantine, Département de Génie Mécanique, route de Ain El Bey, Constantine 25000, Algeria;3. Department of Aerospace Engineering, University of Bristol, Queens Building, University Walk, BS8 1TR Bristol, UK;4. Université de Tizi-Ouzou, Algeria |
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| Abstract: | Although 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 < 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. |
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