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Zanuncio A.J.V.,Federal University of Vicosa | Monteiro T.C.,Federal University of Lavras | Lima J.T.,Federal University of Lavras | Andrade H.B.,V and M Florestal LTDA | Carvalho A.G.,Federal University of Vicosa
BioResources | Year: 2013

Brazil is the world's largest producer of charcoal, mainly for the steel industry. Fresh wood has high moisture content, which reduces its use for energy. Thereby, drying is a fundamental step for charcoal production. This work aimed to determine longitudinal variation in stem diameter, wood basic density, moisture content, and calorific value of Eucalyptus urophylla and Corymbia citriodora logs. These logs were taken from different longitudinal positions on the trees and dried for 90 d; the net calorific value was determined based on the gross calorific value and moisture content. Curves and models were generated based on this data for moisture content and net calorific value during the 90-d period. The logs from the base and middle of C. citriodora trees had lower initial moisture content, and, after 90 d of drying, all logs from the top reached the equilibrium moisture. Drying the logs increased the wood calorific value, with an increase of 49.36%, 63.86%, and 85.98% for those of the base, middle, and top, respectively. The models generated had a high coefficient of determination and a low standard error.

Dos Santos A.,Federal University of Lavras | Zanetti R.,Federal University of Lavras | Fernandes B.V.,V and M Florestal LTDA | Serrao J.E.,Federal University of Vicosa | Zanuncio J.C.,Federal University of Vicosa
Sociobiology | Year: 2011

Subterranean termites are important pests at the initial eucalyptus growth stage and, thus, might be targeted for control. However, sampling methods to determine these insects' infestation degree in cultivated areas are understudied. This paper aimed to study the spatial distribution and identification and samplingplans for subterranean termites at eucalyptus plantations, in cerrado areas of João Pinheiro Municipality, Minas Gerais State, Brazil. Eucalyptus plot areas were divided into continuous parcels of 50 × 50m and corrugated cardboard baits installed in the center of each, where termite individuals were counted. Syntermes spp. foraging holes were counted in circular parcels of 20m radius around each bait. Termite spatial distribution was determined with their individuals colleted by the baits and by the number of Syntermes foraging holes. Optimal random sampling number was calculated through bait data and Syntermes holes were labeled as absent or present. Six different subterranean termite species were colleted with the cardboard baits and they presented a spatial aggregated distribution at the eucalyptus plantation. Based on the results, the number of parcels for subterranean termite sampling with cardboard baits should be 1.36 to 0.18, and the area for Syntermes foraging hole counts should be 5 to 0.27 parcels per hectare, depending on soil type and an estimation error from 10 to 25%.

de Souza E.M.,Federal University of Lavras | da Silva J.R.M.,Federal University of Lavras | Lima J.T.,Federal University of Lavras | Napoli A.,CIRAD - Agricultural Research for Development | And 2 more authors.
Cerne | Year: 2011

Modern technologies for continuous carbonization of Eucalyptus sp. require special care in wood cutting procedures. Choosing the right tool, cutting speeds and feed rates is important to manage time and energy consumption, both of which being critical factors in optimizing production. The objective of this work is to examine the influence of machining parameters on the specifi c cutting energy consumption of Eucalyptus sp. stands MN 463 and VM 01, owned by V&M Florestal. Tests were performed at the Wood Machining Laboratory of the Federal University of Lavras (DCF/UFLA). Moist logs 1.70m in length were used. The experiment was set up using a 3 × 3 × 4 × 2 factorial design (cutting speed × feed rate × number of teeth × tree stand). Results were subjected to analysis of variance and means were compared by the Tukey test at the 5% signifi cance level. Greater cutting speeds, lower feed rates and the 40 teeth circular saw consumed more specifi c energy. Stand MN 463 consumed more specifi c energy. The combination of cutting speed 46 m.s -1, feed rate 17 m.min -1 and 24 teeth circular saw produced better specifi c energy consumption results for stand MN 463. As for stand VM 01, the combination of cutting speed 46 m.s -1, feed rate 17 m.min -1 and 20 teeth circular saw resulted in lower specifi c energy consumption.

Lasmar O.,Federal University of Lavras | Zanetti R.,Federal University of Lavras | os Santos A.,Federal University of Lavras | Fernandes B.V.,V and M Florestal LTDA
Neotropical Entomology | Year: 2012

One of the fundamental steps in pest sampling is the assessment of the population distribution in the field. Several studies have investigated the distribution and appropriate sampling methods for leaf-cutting ants; however, more reliable methods are still required, such as those that use geostatistics. The objective of this study was to determine the spatial distribution and infestation rate of leaf-cutting ant nests in eucalyptus plantations by using geostatistics. The study was carried out in 2008 in two eucalyptus stands in Paraopeba, Minas Gerais, Brazil. All of the nests in the studied area were located and used for the generation of GIS maps, and the spatial pattern of distribution was determined considering the number and size of nests. Each analysis and map was made using the R statistics program and the geoR package. The nest spatial distribution in a savanna area of Minas Gerais was clustered to a certain extent. The models generated allowed the production of kriging maps of areas infested with leaf-cutting ants, where chemical intervention would be necessary, reducing the control costs, impact on humans, and the environment. © 2012 Sociedade Entomológica do Brasil.

Rezende R.N.,Federal University of Lavras | Lima J.T.,Federal University of Lavras | da Silva J.R.M.,Federal University of Lavras | Napoli A.,Federal University of Lavras | And 2 more authors.
Cerne | Year: 2010

Wood drying is one of various stages in the carbonization process, therefore proper monitoring is key to improving yield and obtaining quality charcoal. Prior to being subjected to carbonization by charcoal production plants and once trees have been felled, logs are piled up by the roadside or close to carbonization furnaces and left air drying for 90 days until an optimal 30% moisture content is reached. This work aims to evaluate air drying of logs from an Eucalyptus urophylla clone for carbonization use, analyzing moisture reduction over time and also the influence of log diameter and bark. Logs with and without bark were used, 6.0cm to 21.0cm in diameter, 3.60m in length, with average basic density of 0.496 g/cm3, obtained from a commercial stand of Eucalyptus urophylla at age 8 years. Air drying log piles were arranged outdoors in Paraopeba, Minas Gerais State, Brazil and monitoring consisted of periodiclog weighing for a period of 80 days. At the end of the experiment, higher rates of moisture loss were observed in the three initial weeks. Moisture in logs without bark (54%) and with bark (50%) was close after 80 drying days, with a higher level of moisture reduction being observed for logs without bark. Bark influence on moisture loss was more pronounced in the first three weeks. Moisture reduction varied in intensity as a function of log diameter. After 80 days, the highest level of moisture reduction was observed in logs without bark: 65% for logs larger in diameter and 80% for logs smaller in diameter. As regards logs with bark, results were 56% and 75% respectively.

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