Abstract: This study aims to understand the effect of the initial planting density on the anatomical variability and basic wood density of Schizolobium parahyba var. amazonicum in a planted forest in Amazonia. The effect of the initial planting density on the radial variation from pith to bark of anatomy and basic density was evaluated. There were two planting densities, planting density-I (624 trees ha-1) and planting density-II (312 trees ha-1). Planting density significantly affected only the ray height, fiber length and wall thickness. Radial position was not significant to the height of the rays and the fiber lumen diameter. The interaction planting density × radial position was only significant for the length of the vessel elements, ray frequency and fiber length. The results indicate that the initial planting density influences the radial behavior of certain anatomical characteristics. To obtain gain in terms of total wood per cultivated area, without harm to the density of the produced wood, planting density-I would be most useful, while planting density-II would be suitable for the production of more homogeneous wood, which tends to form adult wood in advance and with some anatomical characteristics appropriate for the plywood industry.

RESUMO Casearia sylvestris SW é uma espécie perene altamente adaptável que é encontrada em toda a América Latina e amplamente disseminada no Brasil. Este trabalho analisou as características ecológicas da anatomia da madeira de C. sylvestris ocorrendo em três tipos de ecossistemas: Cerrado, Floresta da Galeria (Norte de Minas Gerais) e Mata Atlântica (Sul de Minas Gerais). As características qualitativas foram semelhantes entre as plantas nos três ecossistemas, diferindo apenas na distribuição de máculas e tiloses próximas a máculas que eram mais frequentes no Cerrado e na Floresta da Galeria. Os resultados quantitativos mostraram diferenças significativas para vários parâmetros, bem como variação entre indivíduos dos tipos de vegetação do Norte e do Sul de Minas Gerais. A matriz de correlação entre as variáveis, características anatômicas quantitativas, características do solo, altura e diâmetro das plantas, mostrou que as plantas foram agrupadas por tipo de ecossistema. Casearia sylvestris pode adotar diferentes estratégias de sobrevivência em relação à segurança e eficiência do transporte de água pela adaptação ecológica da anatomia da madeira. As características anatômicas adaptativas à seca foram principalmente uma diminuição da frequência do vaso e um aumento da largura e frequência dos raios.

ABSTRACT Casearia sylvestris SW (Salicaceae) is a highly adaptive perennial species that is found throughout Latin America and widely spread in Brazil. This work analyzed the ecological features of wood anatomy of C. sylvestris occurring in three ecosystem types: Cerrado, Gallery Forest (Northern of Minas Gerais) and Mata Atlântica (Southern of Minas Gerais). Qualitative features were similar among plants in the three ecosystems, differing only in the distribution of pith flecks and neighboring tyloses that were more frequent in Cerrado and Gallery Forest. The quantitative results showed significant differences for several parameters, as well as variation between individuals of vegetation types of Northern and Southern of Minas Gerais. The correlation matrix of variables including quantitative anatomical characteristics, soil characteristics, height and diameter of the plants showed that plants were grouped by ecosystem type. Casearia sylvestris might adopt different survival strategies regarding safety and efficiency of water transport by wood anatomy ecological adaptation. The adaptive anatomical features to drought were mostly an decrease of vessel frequency and an increase of ray width and frequency.