Plasticidade de árvores de <i>Eucalyptus grandis</i> no contexto das mudanças climáticas: interação do déficit hídrico e da fertilização no crescimento e qualidade do lenho das árvores

Abstract

Plasticity of Eucalyptus grandis trees in the contexto of climate change: interaction of drought and fertilization on wood growth and quality The plasticity of the Eucalyptus to changes in the climate deserves to be highlighted, mainly because most of the forests implanted in Brazil are generally established in regions of low fertility, poor in potassium (K) and subjected to long periods of drought. Expansion of plantations can be hindered by climate change, with changes in the frequency and intensity of precipitation. The objective of this work is to evaluate the interaction of drought and fertilization with K and sodium (Na) on the growth and quality of E. grandis trees in the context of climate change. In a split-plot experiment installed in June 2010, 54 Eucalyptus trees with five years submitted to two water regimes (100% and 63%) and three fertilizers (K, Na and control) were selected. Sampling was carried out by collecting six discs at the base positions, DBH, 25, 50, 75 and 100% of the total height. The physical properties (apparent density by x-ray densitometry and basic density prediction by NIR), anatomical properties (fibers and vessels) and chemistry (prediction of total extractive content by HI-NIR image acquisition) were evaluated according to the treatments. For the prediction of extractives, the direct prediction and calibration transfer between NIR and HI-NIR equipment was proposed. The transfer was based on a complete calibration base collection measured on both devices. Four calibration transfer models (Update, Repfile, PDS and TOP) were compared. The efficacy of the models was tested in test set samples (1/3 of the total samples). The results show that in all the properties of the wood there was significant effect of the treatments; the apparent density is lower in the trees fertilized with K and Na and without partial throughfall exclusion. The prediction of the basic density presented satisfactory results with RMSECV of 0.022 g/cm³. The fibers are larger in the trees fertilized with K and present a greater thickness of wall in the control trees, both in partial throughfall exclusion. The vessels and the width of the growth rings were influenced, mainly, by partial throughfall exclusion. The direct prediction of the total extractive content was efficacy, showing similar results with the literature for values of predicted and observed Eucalyptus extractives. The K treatment without partial rainfall exclusion had the lowest predicted mean value of total extractives (3.90%). The best calibration transfer model was the TOP, with SEP of 1.53%, SECV of 1.41% and R² of 0.88. The conclusion of this work is that the interaction of water deficit and fertilization influences the wood properties of E. grandis trees and the analyzes carried out allow to draw up more adequate strategies to subsidize the expansion of Brazilian plantation forests in areas subject to long periods of drought.

Dinâmica de deposição de serrapilheira, morfometria da copa e produção de raízes finas de clones híbridos de Eucalyptus urophylla sob estresse hídrico

“…Os valores maiores que 100 para ge indicam que as árvores têm maiores incrementos em altura que em diâmetro (Carmona et al 2018), no caso deste estudo para o período de seca. O déficit hídrico retarda e até interrompe o crescimento secundário das plantas resultante da deposição limitada de células pelo meristema cambial nesse período (Franco 2018). Portanto, os clones podem ter apresentado incremento diamétrico do caule inferior na estação seca devido a atividade cambial estar reduzida nessa época.…”