Winckler Caldeira

Avaliação da eficiência nutricional de três procedências australianas de acácia-negra (Acacia mearnsii De Wild.)

The present study aimed to determine the nutritional efficiency of the macronutrients N, P, K, Ca, Mg and S, in the different components of trees from three provenances of black wattle (Acacia mearnsii De Wild.), 2.4 years old, planted in Butia, RS, Brazil. The selected Australian provenances were Lake George, Bodalla and Batemans Bay. There was a wide variation in the nutritional efficiency among the provenances. In a decreasing ranking for efficiency of nutrient utilization for the production of wood and bark, products that are exploited in the even-aged forest, the following results were obtained: Bodalla > Batemans Bay > Lake George. Although Lake George is less efficient in using nutrients to produce wood, bark and crown, it has a great capacity of production.

Deposição de serapilheira e nutrientes em plantio de Eucalyptus urophylla × E. globulus

ABSTRACT In the present study, we aimed to evaluate the deposition of nutrients and litter in Eucalyptus urophylla × Eucalyptus globulus stands, in the municipality of Eldorado do Sul, Rio Grande do Sul state, Brazil. Four plots (20 m × 20 m) were systematically allocated and four 1 m 2 litter traps were installed in each plot. Litterfall was collected from the traps fortnightly between January 2006 and December 2010. Litter deposition increased proportionally to stand age: 6.9 Mg ha –1 at six and 8.5 Mg ha –1 at nine years of age. Leaf fraction represented 66.9% of the total litter on average, followed by twigs (14.7%), miscellaneous (10.5%), and thick branches (7.9%). Litter deposition showed seasonal behavior, increasing as the air temperature increased. The leaf fraction produced the highest nutrient release through litter, with average values of 58.2 and 81.8% for Cu and N, respectively. Keywords: forest nutrition, nutrient release, forest sustainability, nutrient cycling. Floresta e Ambiente 2014 jul./set.; 21(3):327-338Artigo Original