Time filter

Source Type

Mucuri, Brazil

Ferreira M.A.,Federal University of Lavras | Zauza E.A.V.,Suzano Papel e Celulose | Silva J.F.,Melhoramento Florestal | Colodette J.L.,Federal University of Vicosa | Alfenas A.C.,Federal University of Vicosa
Forest Pathology | Year: 2013

In this study, we determined the effects of Ceratocystis fimbriata wilt on volumetric growth and cellulose pulp yield of eucalyptus. Seven-year-old healthy and infected trees were separated into different classes of severity, and the individual volume of each whole tree with bark was determined. Volumetric losses were found regardless of the class of disease severity, resulting in reduction in volumetric growth of the trees from 65% to 87%, depending on the infection level. Two approaches were used for evaluating the effects of the disease on cellulose pulp yield: (i) evaluation of wood basic density and chemical composition, contents of ethanol/toluene extractives and Klason lignin, and the alkaline load and screen yield across Kraft pulping to kappa number 18 ± 0.5 for both healthy and discoloured materials; (ii) determination of the alkaline load and yield across Kraft pulping to kappa number 18 ± 0.5 of woods with different levels of discoloration (0, 25, 50, 75 and 100% of discoloured wood). Discoloured wood presented lower basic density, higher ethanol/toluene extractives and Klason lignin, higher alkaline load and lower pulp screened yield at kappa number 18 ± 0.5 compared with the healthy ones. Increasing the fraction of infected wood in chip furnishes resulted in proportionally increased alkaline load demand and decreased screen yields. Adding 50% of infected wood in the chip furnish resulted in 23.8% increase in the alkali load and 13.7% reduction in the pulp screen yield at kappa number 18 ± 0.5. The results obtained have proved that the disease reduces volumetric growth, increases wood consumption and reduces yield in eucalyptus pulp production. © 2013 Blackwell Verlag GmbH. Source

da Silva R.M.L.,International Paper of Brazil Rod | Hakamada R.E.,University of Sao Paulo | Bazani J.H.,4tree Agroflorestal | Otto M.S.G.,4tree Agroflorestal | And 2 more authors.
Forests | Year: 2016

Fertilization increases productivity in Eucalyptus plantations, but losses in productivityassociated with soil fertility continue at operational scales. In this study, we evaluated the fertilizationresponse (FR), light use efficiency (LUE) and growth efficiency (GE), i.e., the amount of wood biomassaccumulated per unit of light absorbed (LUE) and per unit of leaf area index of Eucalyptus plantations.We used a "twin plot" approach, with 161 blocks representing 52,700 ha of planted forests thatspanned a broad range of edaphoclimatic conditions in southeastern Brazil. The normal plots (NP)were part of a permanent inventory network, whereas the twin plots (TP) received extra high levelsof fertilization and extra weed control after fertilization. The intensive management (twin plots) ledto a large increase of 5.3 Mg· ha-1· year-1 of wood increment. The region without dry periods andwith soils with high clay content was most responsive to fertilization, with a 15% increment in theLUE and 10% increase in the GE of the TPs compared with those of the NPs. Our results suggestedthat water availability was the primary element affecting productivity and potential response tofertilization. With this information, decisions can be made on which regions should receive priorityfertilization investments. However, more research is required to determine the most limiting nutrientin each type of environment. © 2016 by the authors. Source

Zauza E.A.V.,Suzano Papel e Celulose | Lana V.M.,Federal University of Vicosa | Maffia L.A.,Federal University of Vicosa | Araujo M.M.F.C.,Federal University of Vicosa | And 3 more authors.
Forest Pathology | Year: 2015

To identify and implement Puccinia psidii control strategies, it is essential to understand the role of environmental factors on rust-disease development and spread among eucalypt (Eucalyptus spp.) plantations. In this study, we evaluated the wind dispersal of P. psidii urediniospores and the progress of eucalypt rust in a field trial in Brazil. Urediniospores of P. psidii were trapped in a Burkard® spore trap from July 2004 to June 2005. To evaluate the progress of eucalypt rust, plots were established in March 2002 using a clonal hedge scheme. The incidence of both branches and leaves with rust was assessed weekly from February 2003 to October 2005. Disease progress was studied using time-series analysis. Urediniospores were trapped on 77% of the days sampled. The highest average urediniospore concentration was detected from July to November, and most of the urediniospores (58%) were trapped at night. Urediniospore concentration was negatively correlated with rainfall, light intensity, minimum, average and maximum temperatures and wind speed, whereas urediniospore concentration was positively correlated with leaf-wetness duration and relative humidity. From December 2004 to June 2005, average urediniospore concentration was 0.22 spores m-3 air h-1 and had no correlation with meteorological data. The highest average urediniospore concentration was associated with a combination of low average temperature, low light intensity, low wind speed, high relative humidity and high leaf wetness, which reflect conditions observed at night. The disease incidence was positively correlated with the urediniospores trapped at 12 days prior to disease assessment. According to the models obtained by the time series, a seasonal yearly effect was found on rust progress. Using our models, we were also able to forecast disease incidence up to 3 months after the last field assessment. © 2014 Blackwell Verlag GmbH. Source

Goncalves J.L.D.M.,University of Sao Paulo | Alvares C.A.,Institute Pesquisas e Estudos Florestais e FPC | Goncalves T.D.,Fundacao Nacional Do Indio | Moreira R.M.,University of Sao Paulo | And 2 more authors.
Scientia Forestalis/Forest Sciences | Year: 2012

Detailed environmental land characterization is essential for technical and financial planning, for both the scientific point of view and technological application. This work aimed at the physiographic and pedological characterization and eucalyptus productivity mapping at Itatinga Forest Sciences Experimental Station (southeastern Brazil), using geographic information systems in order to identify possible cause-effect relationships between forest productivity and soil attributes. The digital cartographic dataset was structured as follows: as primary source of data, aerial photograph and field survey were used and, as a secondary source, topographical, geological and land use occupation maps were used. For mapping wood productivity at age six (MAI6, Mean Annual Increment), inventory data of permanent plots (same species, provenance and age) were used, which were obtained from Eucalyptus grandis plantations. Using simple linear correlation and backward stepwise multiple regression analysis, the dependent variable (MAI) was related with physical and chemical characteristics of the soils. Two standards of contour curves were identified, one with close curves, narrow and surrounding the drainage network, in the steeper and lower altitude areas; the other, with spaced contour lines, in the areas of higher altitude and with plane relief. Six types of soils were characterized as being highly related to the physiographic patterns of the area: loamy sandy to sandy clayey Typic Hapludox (LVAd, 47.5%), clayey Rhodic Hapludox (LVd1, 33.4%), sandy clay Rhodic Hapludox (LVd2, 6%), clayey Rhodic Hapludox (LVdf, 9.1%), Entisols (G, 3.4%) and Fluvents soil (RY, 0.6%). There were large variations in wood productivity in the Eucalyptus grandis plantations, characterized in six classes, ranging from 26 to 52 m 1 ha -1 yr -1. These productivity changes were strictly related to soil mapping units. Through multiple regression analysis, we found that clay and organic matter contents were the attributes which most strongly explained the productivity differences. Source

Ryan M.G.,U.S. Department of Agriculture | Ryan M.G.,Colorado State University | Stape J.L.,North Carolina State University | Binkley D.,Colorado State University | And 13 more authors.
Forest Ecology and Management | Year: 2010

Wood production varies substantially with resource availability, and the variation in wood production can result from several mechanisms: increased photosynthesis, and changes in partitioning of photosynthesis to wood production, belowground flux, foliage production or respiration. An understanding of the mechanistic basis for patterns in wood production within a stand and across landscapes requires a complete annual carbon budget. We measured annual carbon flows to wood production, foliage production and total belowground carbon flux (the sum of root production, root respiration, and mycorrhizal production and respiration) from ages three to five years in clonal Eucalyptus plantations at four sites in Brazil to test if fertility, water availability and stand structure changed wood production and by what mechanism. We also quantified the patterns in light interception and the efficiency of light use to provide additional mechanistic insights into growth responses and to determine if light-use efficiency was related to changes in flux and partitioning. The routine level of forest fertilization at these four sites was high enough that further increases in nutrient supply did not increase wood growth. Irrigation increased wood net primary productivity (age three to five) from 1.45 to 1.84 kg m-2 year-1 of C (27%), because of increases in light interception (5%), photosynthetic efficiency (from 0.028 to 0.031 mol C/mol photons absorbed, 11%), gross primary productivity (from 3.62 to 4.28 m-2 year-1 of C, 18%), and partitioning to wood (from 0.397 to 0.430 of photosynthesis, 8%). These changes increased light-use efficiency by 20%. Annual flux belowground varied among sites from 0.43 to 1.0 m-2 year-1 of C but did not vary with water availability. Across the four sites for the irrigated and unirrigated treatments, light-use efficiency was positively correlated with gross primary productivity and partitioning to wood production. Increasing heterogeneity of stand structure (resulting from staggered timing of planting within plots) led to a 14% loss in wood biomass relative to uniform stand structure at age six. Light-use efficiency, gross primary productivity, and wood net primary productivity were lower, but not significantly so, in heterogeneous compared to uniform stands. Source

Discover hidden collaborations