944 resultados para Tree species impoverishment


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Agronomia - FEIS

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Pós-graduação em Ciência Florestal - FCA

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This study has investigated the genetic variation for silvicultural traits in an open-pollinated progeny test of Astronium graveolens Jacq., established at Luiz Antônio Experimental Station (State of São Paulo, Brazil). The trial was planted in a random block experimental design, containing 23 families, six replications and five plants per plot. The traits measured were diameter at breast height (DBH), total height and stem form. The assessments were taken at the age of 19 years. Significant differences were not detected by the analysis of variance, suggesting that the genetic variation was low, as well as the probability to raising genetic gains through selection among progenies. The coefficient of genetic variation was moderate for the traits height (8.2%) and DBH (21.2%) and low to stem form (4.0%). However, the average coefficient of heritability among progenies was low for all studied traits (ranging from 0.02 to 0.15), confirming the low probability of genetic improvement of this population by selection among progenies.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Pós-graduação em Agronomia - FEIS

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There are strong uncertainties regarding LAI dynamics in forest ecosystems in response to climate change. While empirical growth & yield models (G&YMs) provide good estimations of tree growth at the stand level on a yearly to decennial scale, process-based models (PBMs) use LAI dynamics as a key variable for enabling the accurate prediction of tree growth over short time scales. Bridging the gap between PBMs and G&YMs could improve the prediction of forest growth and, therefore, carbon, water and nutrient fluxes by combining modeling approaches at the stand level.Our study aimed to estimate monthly changes of leaf area in response to climate variations from sparse measurements of foliage area and biomass. A leaf population probabilistic model (SLCD) was designed to simulate foliage renewal. The leaf population was distributed in monthly cohorts, and the total population size was limited depending on forest age and productivity. Foliage dynamics were driven by a foliation function and the probabilities ruling leaf aging or fall. Their formulation depends on the forest environment.The model was applied to three tree species growing under contrasting climates and soil types. In tropical Brazilian evergreen broadleaf eucalypt plantations, the phenology was described using 8 parameters. A multi-objective evolutionary algorithm method (MOEA) was used to fit the model parameters on litterfall and LAI data over an entire stand rotation. Field measurements from a second eucalypt stand were used to validate the model. Seasonal LAI changes were accurately rendered for both sites (R-2 = 0.898 adjustment, R-2 = 0.698 validation). Litterfall production was correctly simulated (R-2 = 0.562, R-2 = 0.4018 validation) and may be improved by using additional validation data in future work. In two French temperate deciduous forests (beech and oak), we adapted phenological sub-modules of the CASTANEA model to simulate canopy dynamics, and SLCD was validated using LAI measurements. The phenological patterns were simulated with good accuracy in the two cases studied. However, IA/max was not accurately simulated in the beech forest, and further improvement is required.Our probabilistic approach is expected to contribute to improving predictions of LAI dynamics. The model formalism is general and suitable to broadleaf forests for a large range of ecological conditions. (C) 2014 Elsevier B.V. All rights reserved.

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Further to increase the wood yield, is important goal of forest tree breeding the adaptation of clones through diverse environment, especially for soil and climate. Perennial tree species such as eucalypts, have a long life cycle and the frosts can occur and to be their limiting source of cultivation. The aim of the study was to determine the genetic variability and the genetic correlations between selection ages of clones cultivated in the municipality of Palma So la, SC, Brazil, where frosts are common in the winter. A clonal trial was set up in 2008 in Palma So la, by statistical design of randomized complete blocks considering 29 clones, six replications, six plants per plot, and 3.0m x 3.0 m spacing. The silvicultural characters of total plant height, diameter of breast height (dbh), and wood volume were evaluated through 24, 36, 48, and 60 months old. The deviance analysis and estimates of genetic parameters were based on the REML / BLUP genetic statistical procedure. Significant differences were observed for all traits in the deviance analysis. High correlations and statistically significant between characters were observed, indicating that the early selection will provide significant gains. Part of the clones USP/IPEF 64, USP/IPEF 78, USP/IPEF 52, USP/IPEF 68, and USP/IPEF 74) are potential to be used into the breeding programs and in commercial stands into the studied frost regions.

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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV