Clonal production of eucalyptus seedlings has made considerable progress in recent years. Significant developments have taken place in irrigation and fertilization systems as well as in management of clonal miniorchards. However, the proportion of leaf area in stem minicuttings remains almost the same as that used in macrocutting systems. This work aimed to evaluate the effect of leaf area reduction on seedling production of eight eucalyptus clones. The experiment was conducted over a period of 105 days using a randomized block design and three replicates in an 8 x 4 factorial arrangement, with eight clones and four leaf reduction levels (0%, 25%, 50% and 75%). Variables evaluated included height, root collar diameter, shoot and root dry matter and relationships between these variables. Experimental results demonstrated that clones behaved differently as to leaf reduction and that the 0% reduction level can be adopted in most clones being evaluated.

Conduziu-se este trabalho, com o objetivo de avaliar o efeito da aplicação de Fert-Bokashi® sobre a sobrevivência e crescimento de mudas de dois clones de Eucalyptus urophylla propagados pela técnica de miniestaquia. O experimento foi conduzido por um período de 28 dias, utilizando um delineamento experimental em blocos casualizados com três repetições, no esquema fatorial 6 x 2, sendo seis concentrações de Fert- Bokashi® (0,0%, 0,1%; 0,3%: 0,5%; 0,7% e 0,9%) e dois clones. Avaliou-se a sobrevivência das mudas, o crescimento em altura e a matéria seca da parte aérea, das raízes e total. Os resultados obtidos demonstraram que o Fert-Bokashi® não exerceu efeito significativo sobre a sobrevivência e o crescimento das mudas dos dois clones de Eucalyptus urophylla.

The Orinoco region, is the one with the largest area for forest development. Nonetheless, some of its soils are acid and characterized by low fertility levels, which has considerably limited plantation productivity. Therefore, this study aimed at assessing the effects of soil fertilizing and liming by using phosphorus and potassium on 34-month-old Eucalyptus pellita productivity. Tests have been carried out at: Villanueva, Casanare; Puerto Lopez, Meta and La Primavera, Vichada, under a random block design with a factor arrangement of 3x3x3, equivalent to: 0, 1 and 3 Mg ha-1 of dolomitic lime (LIME); 30, 75 and 120 kg ha-1 of P (P2O5) as well as 60, 120 and 180 kg ha-1 of K (K2O). Timber productivity volume was assessed 34 months after planting, obtaining significant differences. In Puerto Lopez, LIME effect on E. pellita growth followed a simple linear model, whereas a logarithmic behavior was observed in La Primavera and Villanueva. P2O5 effect (p<0.01) on timber volume was observed only in La Primavera, following a square-root model. K2O did not have a significant effect (p>0.05) on E. pellita growth. The results obtained indicate the positive effect on E. pellita growth in the three areas of study by using doses of approximately 1 Mg ha-1 of lime; and 120 kg ha-1 of P2O5 in La Primavera.

For the development of nutrient budget models to recommend lime and fertilizers for agricultural and forestry crops, curves of plant growth and nutrient accumulation are required. Information about how nutrients are partitioned between the different plant organs is also necessary, but still scarce for pine in Brazil. This study evaluated the growth, biomass partitioning, and nutrient dynamics in pine forests in southern Brazil. To this end, we assessed unthinned 2, 4, 6, and 8-year-old stands of Pinus taeda L. Three plots of 20 × 30 m per stand were delimited, in which three trees of different classes of diameter at breast height (DBH) were chosen. These trees were measured, felled, and the weight of their fresh components (leaves, branches, bark, and wood) was evaluated. Samples of each tree compartment and from the forest litter were taken to determine dry weight and nutrient content. From trees of the mean DBH class, the roots were also collected and the dry weight and nutrient contents determined. The same sampling procedure was carried out with soil for physical and chemical characterization. Regression models were adjusted to estimate growth, nutrient uptake, and nutrient use efficiency of pine trees, based on data collected in this and previous studies. The equations developed in this research can be used in nutrient budget models as well as in other simulation models, to establish recommendations of lime and fertilizers for Pinus taeda stands in southern Brazil.

A modelagem do crescimento e produção florestal é um grande desafio para os gestores florestais em função da grande quantidade de variáveis envolvidas e da importância das estimativas geradas para a tomada de decisão no empreendimento florestal. Diversos métodos estatísticos e de inteligência artificial podem ser utilizados visando a verificação da importância das variáveis e seleção das mesmas para o processo de modelagem florestal. Neste estudo é demostrado o uso do método de perturbação em modelos de Redes Neurais Artificiais na definição da importância relativa de variáveis preditoras (silviculturais, climáticas e de manejo) da produtividade de povoamentos de eucalipto ao final da rotação (produção florestal). Foram utilizados dados de 320 talhões de plantios de eucalipto localizados no norte do Estado de Minas Gerais, com idade superior a sete anos. A precipitação distribuída em diversas idades e o teor de argila do solo foram as variáveis de maior importância para a predição do volume na idade de corte.