Modulador edáfico para uso em modelo ecofisiológico e produtividade potencial de povoamentos de eucalipto

• Autor(a) principal: Borges, Jarbas Silva
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1632
• topic: Modelo 3-PG; Produtividade potencial; Análise foliar; Linha de fronteira; Model 3-PG; Potential productivity; Leaf analysis; Boundary line; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

The rate of expansion of eucalyptus plantations in Brazil has generated concern about its effects on the physical resources, especially soil and water, and the sustainability of these systems, when intensively managed. In this sense, process-based growth models such as 3-PG has obtained prominence since they are responsive to the environmental and site conditions changes and have high predictive and explanation power, which allows increasing our ability to understand and predict forest growth. However, despite good results, the 3-PG model has low sensitivity to the different management units and or soil classes,but it is very responsive to soil fertility. Thus, it is necessary and desirable to develop an edaphic modulator that reflects the effects of soil on the flow of water and nutrients for use in the 3-PG. Such modulator can be based on leaf analysis results, since the nutrient content in the leaf besides reflect the flow of water and nutrients in the soil, correlate with the growth and production of the plants. Therefore, the objectives of the present research were: assess the degree of universality of the parameterization of 3-PG available for Brazil; determine the eucalyptus potential productivity in different regions of Brazil; and develop modulator based on leaf analysis that incorporates the soil effects on productivity, for use in ecophysiological models. It was concluded that: a) the use of the Kenworthy balanced index and of boundary line approach applied to the leaf analysis results in young eucalyptus stands allow to determine the degree of limitation to productivity due to degree of balance of each nutrient, isolating the effects of factors non-nutritional, and basing the determination of edaphic modulator for use in ecophysiological forest growth models; b) the strategy for obtaining the parameterization of the 3-PG model influences the degree of universality of the model parameterization. Parameterizations obtained in plots of trials irrigated / fertirrigated have low universality while the parameterization obtained in commercial plantations has high universality and thus a high degree of extrapolation; c) the potential productivity of eucalyptus wood (stem without bark) to the six years, to Brazil, under the influence of climate, considering the range covered by mean ± 1 standard deviation (69 % of simulated sites) ranges from 42.3 to 73.4 m3/ha/year; d) the rainfall, the solar radiation, the rainfall distribution and the maximum temperature influence, in that order, eucalyptus potential productivity in the Brazil under the effect of climate; e) about the nutritional demand for eucalyptus production (stem) it has the following order: Ca > N > K > Mg > P. Considering the range covering about 69 % of simulated sites (mean ± 1 standard deviation), it has the following ranges to the quantities of nutrients accumulated in the stem: 227 - 393, 17 - 30, 136 - 236, 340 590, and 62 - 107 kg/ha for N, P, K, Ca and Mg, respectively.