ALOCAÇÃO DE NUTRIENTES EM POVOAMENOS DE Eucalyptus saligna Sm. NA REGIÃO DE GUAÍBA - RIO GRANDE DO SUL

Abstract

ALOCAÇÃO DE NUTRIENTES EM POVOAMENOS DE Eucalyptus saligna Sm.NA REGIÃO DE GUAÍBA -RIO GRANDE DO SUL RESUMO: Este trabalho, realizado em povoamentos de Eucalyptus saligna Sm., entre 2 e 7 anos de idade, na região de Guaíba -RS, teve como objetivo: estimar o estoque de nutrientes na biomassa. Com base no inventário florestal, árvores de diâmetro médio foram coletadas e fracionadas em folha, galho, casca do tronco, madeira do tronco e raiz. A serapilheira acumulada foi avaliada com unidades amostrais de 1 m 2 . Amostras dos componentes arbóreos e de serapilheira foram coletadas para estimativa da massa seca e da concentração de nutrientes. O estoque de nutrientes foi obtido pelo produto entre a biomassa média de cada componente e a concentração média de nutrientes. Para a média dos povoamentos, o estoque de nutrientes apresentou a seguinte ordem de acúmulo, para os componentes da biomassa: madeira do tronco > raiz > folha > casca > galho; e para nutrientes: Ca > N > K > Mg> P. NUTRIENT ALLOCATION IN Eucalyptus saligna Sm. STANDS IN THE REGION OF GUAÍBA -RIO GRANDE DO SULABSTRACT: This research conducted in Eucalyptus saligna Sm. stands, between 2 and 7 years of age, in the region of Guaíba -RS, had as objective: to estimate the nutrients stock in the biomass. On the basis of the forest inventory, trees of medium diameter were collected and fractionated in leaf, branch, bark, wood and root. The accumulated litter was evaluated with sampling units of 1 m 2 . Samples of arboreal components and litter were collected to estimate the dry matter and nutritional content. Nutrients stock was obtained through the product between the average biomass of each component and the average concentration of nutrients. For the average of stands, the stock of nutrients showed the following order of accumulation, for biomass components: wood > root > leaf > bark > branch; and for nutrients: Ca > N > K > Mg > P.

Sequential Management of Commercial Rosewood (Aniba rosaeodora Ducke) Plantations in Central Amazonia: Seeking Sustainable Models for Essential Oil Production

“…From a long-term management perspective, three or four crop rotations per pruning would be required for the levels of exported nutrients to equal those exported in a single harvest where a whole tree is cut and removed. Similar results have been reported by Witschoreck and Shumacher [31], in a study of Eucalyptus saligna management. These authors concluded that harvest intensity may represent the difference between a sustainable nutritional management and one deleterious to nutrient reserves.…”

“…At present, all the waste is used as fuel (burned) in the extraction process itself. The objective of this work was to evaluate nutrient replacement techniques permitting maintenance of available soil nutrient levels after harvesting [31], what was done with the two harvest types applied. This is important since, given the international market requirements for use of synthetic industrial fertilizers and non-organic pesticide use, there is a need to determine whether the nutrient cycles in Amazonian soils in areas producing rosewood can be maintained through the natural biochemical processes themselves.…”

“…In consequence, interactions between such tree crops and nutrient cycling need to be studied if sustainable forest management is to be guaranteed. Replacing exported nutrients is one method by which sustainable use of production sites can be achieved [30,31], but to do this effectively for rosewood it is necessary to know the nutrient profile of its commercializable biomass.…”

Nutrient accumulation in Eucalyptus bark at different population densities

“…The next highest nutrient was N (15-31%), followed by K (8-13%) (Figure 4). Viera et al (2015) evaluated the nutritional implications of different harvesting intensities on 10-year-old E. urophylla × E. globulus hybrids at a density of 1142 trees per ha -1 and found in the bark: 75 kg ha -1 N, 15 kg ha -1 P, 131 kg ha -1 K, 429 kg ha -1 Ca, 92 kg ha -1 Mg, and 11 kg ha -1 S. Witschoreck & Schumacher (2015) estimated the nutrient stock in different components of the biomass of E. saligna at 7 years-of-age with a density between 1111 and 1666 trees ha -1 , and found: 54 kg ha -1 N, 7 kg ha -1 P, 55 kg ha -1 K, 241 kg ha -1 Ca, and 54 kg ha -1 Mg. SV -Source of variation; C -Clone; P.D -Population density; CV -Coefficient of variation; G × D.P -Interaction of clone and density factors; ns -Not significant; *Significant by F test at 0.05 probability. The means followed by the same letter, upper case in the row and lower in the column, do not differ from each other by Tukey's test at 0.05 probability lower amounts of nutrients at 833 and 1111 trees ha -1 , respectively.…”

“…One of the benefits of maintaining forest residues on the soil is the reduction of nutrient exports, which is retained within the bark. Although the bark represents approximately 8% of the biomass of the Eucalyptus trunk, it contains about 18, 19, 21, 60, and 48% of N, P, K, Ca, and Mg content, respectively (Paes et al, 2013;Witschoreck & Schumacher, 2015). These amounts reflect the importance of bark in nutrient cycling because a large portion of these nutrients are allocated to the tree and are usually removed from the site during logging.…”