INPUTS OPTIMIZATION IN THE SEEDLINGS PRODUCTION OF Corymbia citriodora E Eucalyptus dunnii

Corymbia citriodora and Eucalyptus dunnii are species of relevant importance due to the quality of the wood and growth potential in Southern Brazil. Therefore, we aimed to identify containers and doses of controlled-release fertilizer capable of enhancing the morphophysiological quality and growth of these species in the nursery, aiming for the proper management of these inputs. The seedlings were produced in two volumes of containers (50 e 110 cm³), filled with Sphagnum peat-based substrate, mixed with different doses of controlled-release fertilizer (CRF) NPK 15-09-12 (0, 3, 6, 9 e 12 g L-1 of substrates). In addition, the morphological (height, stem diameter, leaf area, dry weight of shoot, root, and total) and physiological (chlorophyll a and b index and quantum yield of the photosystem II) attributes were evaluated. The morphological attributes proved to be suitable indicators of the quality of C. citriodora and E. dunnii seedlings, allowing to recommend the container of 50 cm³ and the doses of 9.0 g L-1 of controlled-release fertilizer for both species. At the same time, the physiological variables evaluated were not responsive to the effect of the treatments.

HAND-ARM VIBRATION IN DIFFERENT OPERATING CONDITIONS WITH A CHAINSAW

The mechanization of forest harvesting is a trend in Brazil. However, small and medium-sized companies in the forestry sector, even today, opt for semi-mechanized harvesting, using chainsaws for the harvesting and sectioning of trees. Despite technological advances, when operated continuously, chainsaws may cause damage to the operator’s body, acting as a stressor, and vibration excess is responsible for numerous health disorders, among them the Raynaud syndrome. In this sense, this study aimed to determine the vibration levels to which a chainsaw operator is subjected, during the transversal cut (tracing) of the wood, in different forest species and cutting sets. The treatments consisted of three forest species (Eucalyptus grandis, Eucalyptus dunnii and Acacia mearnsii De Wild) and two cutting sets, consisting of square tooth chains of the semi-chisel and chisel types. The vibration assessment was based on the criteria established by the Regulatory Standards NR15, NHO10 and ISO 2631-4. The results of vibration levels were higher than the reference limits established by ISO 2631-4, and, for both cutting sets, the highest vibration levels occurred on the “x” axis. After the data processing, the acceleration values resulting from the normalized exposure to hand-arm vibrations showed significant differences for the “y” and “z” axes. Therefore, it can be inferred that the chainsaw operation is a stressor, potentially capable of causing damage to workers' health.

Estimation of wood volume of Eucalyptus dunnii and urograndis of different ages using TM/Landsat 5i

O objetivo deste estudo foi a geração de modelos de volume comercial com casca (Vcc) em povoamentos de Eucalyptus dunnii e urograndis em diferentes estágios de crescimento e condições de sítio, utilizando dados de reflectância das diferentes regiões do espectro eletromagnético e de índices de vegetação. As regressões lineares múltiplas geradas resultaram em três modelos preditivos, sendo que os mais significativos, em ordem decrescente foram para as espécies de Eucalyptus dunnii e Eucalyptus urograndis com 50 e 59 meses de idade, respectivamente, seguido pelo modelo para Eucalyptus urograndis de 25 meses, apesar da equação de regressão para Eucalyptus dunnii de 34 meses, não tenha sido significativa. O índice de vegetação ajustado ao solo (SAVI 0,5) mostrou-se relevante na construção dos três modelos, pelos diferentes graus de contribuição da componente solo, decorrente do não fechamento das copas em povoamentos jovens de diferentes idades. A região do infravermelho de ondas curtas (SWIR 1) também compôs os modelos de Eucalyptus dunnii e Eucalyptus urograndis, analisados conjuntamente e o modelo preditivo para Eucalyptus dunnii, demonstrando a importância da estrutura do dossel florestal por esta região do espectro eletromagnético estar relacionada ao aumento do conteúdo de lignina e em decorrência da evolução de sua capacidade produtiva.

Use of Optimization Modeling to Assess the Effect of Timber and Carbon Pricing on Harvest Scheduling, Carbon Sequestration, and Net Present Value of Eucalyptus Plantations

Quantifying the impact of carbon (C) and timber prices on harvest scheduling and economic returns is essential to define strategies for the sustainable management of short-rotation plantations so that they can provide timber products and contribute to C sequestration. In this paper, we present a mixed-integer linear programming model that optimizes harvest scheduling at the forest level, C sequestration, and Net Present Value (NPV) over a planning period of up to 15 years. The model included revenue from the sale of timber (pulplogs) and credits from the net C sequestered during the life of the stands. In addition, plantation establishment, management, harvesting, and transportation costs were included in the analysis. The study area comprised 88 Eucalyptus grandis W. Hill and Eucalyptus dunnii Maiden stands located in Uruguay, totaling a forest area of nearly 1,882 ha. The study investigated the impact of C and timber prices on NPV, harvest schedules, stands’ harvest age, timber flows to customers, and C sequestered per period. The maximum NPV among all the scenarios evaluated (USD 7.53 M) was calculated for a C price of 30 USD t−1, an interest rate of 6%, and a timber price of 75 USD m−3. This was USD 2.14 M higher than the scenario with the same parameters but that included only revenue from timber. C prices also impacted stands’ harvest age, C sequestration, and timber flows delivered to end customers. On average, in scenarios that included C prices, timber flows and C sequestration increased by 15.4 and 12.1%, respectively, when C price increased from 5 to 30 USD t−1. These results demonstrate that harvest scheduling, harvest age, and NPV are very sensitive to C and timber, and that the best economic returns are obtained when the stands are managed to maximize timber production and C sequestration.

Fertilização em Eucalyptus dunnii Maiden no bioma Pampa - Brasil

In silviculture, mineral fertilization is necessary to supply the nutritional demand, however, the recommendation of the quantities to be applied should aim at maintaining the productive capacity of the soil. The purpose of this study is to test whether increasing the recommended fertilizer dose improves soil fertility and increases the productivity of Eucalyptus dunnii in sites in the central region of the Pampa biome, Brazil. The doses of 150 g (T0), 225 g (T1) and 450 g (T2) of N-P2O5-K2O were applied 24:00:24 per plant, after 14 months of planting. In all tested doses, the species productivity is considered satisfactory for the site. There was an improvement in soil fertility, especially in potassium contents, in addition to a higher individual volume of Eucalyptus dunnii trees after the application of the dose of 450 g plant-1 of N-P2O5-K2O, 24:00:24 in coverage (T2).