Aliny Aparecida dos Reis

CONTINUIDADE ESPACIAL DE CARACTERÍSTICAS DENDROMÉTRICAS EM POVOAMENTOS CLONAIS DE EUCALYPTUS SP. AVALIADA AO LONGO DO TEMPO

O objetivo deste estudo foi avaliar a continuidade espacial ao longo do tempo (para 5 idades consecutivas) das caracteristicas dendrometricas altura dominante media, volume e incremento medio anual em povoamentos clonais de Eucalyptus sp no estado de Minas Geais. A area foi plantada em 2003, perfazendo um total de 1.072,6 hectares. Os dados foram oriundos de um conjunto de 116 parcelas permanentes, onde foi realizado inventario florestal sucessivo entre os anos de 2006 e 2010. Aos semivariogramas experimentais, foram ajustados os modelos esferico, exponencial e gaussiano pelo Metodo dos Minimos Quadrados Ponderados, para cada idade, selecionando-se o mais adequado com base no erro medio reduzido e desvio padrao do erro medio reduzido da validacao cruzada. O comportamento dos semivariogramas foram comparados entre as respectivas medicoes com base no plotagem dos mesmos de forma escalonada, permitindo avaliar se a estrutura espacial foi alterada com a idade do plantio. O modelo exponencial apresentou-se como o de melhor ajuste e todas as caracteristicas apresentaram-se estruturadas espacialmente, com os modelos espaciais sendo semelhantes entre as idades do povoamento e para as caracteristicas estudadas. Foi possivel verificar que o grau de continuidade espacial se manteve ao longo dos anos para as caracteristicas avaliadas e que o semivariograma escalonado demonstrou que a estrutura espacial das caracteristicas e semelhante entre as diferentes idades do povoamento. Os resultados evidenciam que a utilizacao de metodos geoestatisticos para avaliar o crescimento de povoamentos de eucalipto ao longo do tempo, consiste de uma importante ferramenta de planejamento, permitindo um melhor acompanhamento e uma predicao mais precisa do volume de madeira da floresta, levando em consideracao a estrutura de dependencia espacial.

EFEITO DA IDADE E CLONE NA QUALIDADE DA MADEIRA DE Eucalyptus spp VISANDO À PRODUÇÃO DE BIOENERGIA

The aim of this work was to evaluate the effect of age and clone on the quality of Eucalyptus spp wood aiming the production of charcoal and bioenergy. Four Eucalyptus spp clones at the ages of 57 and 69 months were evaluated. Four trees per clone in each age were evaluated. The average basic density, the basic density at the DBH, higher heating value and contents of lignin, total extractives, ashes, holocellulose an elemental chemica analylsis (C, H, N, S and O) were evaluated. In the evaluation of the assay, and entirely randomized design in the factorial scheme 4 x 2 was used. Besides, a multivariate analysis of main components was made. In general, it was observed effect of age on wood quality. Ash, hydrogen and nitrogen contents tended to diminish with increases in age for all the clones evaluated. However, oxygen content presented an increase with the increase in age of the clones. Lignin content presented significant increase with age increase, being the contrary observed for holocellulose content. The clones at the age of 69 months presented the highest contents of lignin, but the same did not happen for basic density of wood. The clones I144 and I220 had the highest average values for this characteristic, what may be advantageous for charcoal production.

DETECÇÃO DA EXPANSÃO DA ÁREA MINERADA NO QUADRILÁTERO FERRÍFERO, MINAS GERAIS, NO PERÍODO DE 1985 A 2011 ATRAVÉS DE TÉCNICAS DE SENSORIAMENTO REMOTO

O objetivo deste estudo foi analisar a evolucao da area minerada no Quadrilatero Ferrifero (QF), Minas Gerais, e quantificar a area coberta com vegetacao florestal nativa que foi suprimida por esta atividade durante os ultimos 26 anos. Foram utilizadas imagens TM/Landsat 5 correspondente a area de estudo nos anos de 1985, 1989, 2000 e 2011. Para cada ano de analise, utilizando tecnicas de interpretacao visual de imagens, foram criados poligonos identificando e delimitando as areas mineradas. Para a analise da supressao da vegetacao florestal nativa pela mineracao, as imagens de 1985 foram classificadas gerando um mapa tematico de uso e cobertura do solo do QF. Em seguida, os poligonos de mineracao identificados em cada ano de analise foram sobrepostos ao mapa da vegetacao nativa possibilitando o calculo da area de vegetacao florestal nativa suprimida pela expansao da mineracao. Entre os anos de 1985 a 2011, observou-se aumento de 213% na area minerada no QF. As areas suprimidas de vegetacao florestal nativa entre os anos de 1985 a 1989, 1989 a 2000 e 2000 a 2011 corresponderam respectivamente a 324,42 ha, 948,98 ha e 1989,68 ha, com uma perda total de vegetacao nativa de 3.263,07 ha

Relationship Between Spectral Data and Dendrometric Variables in Eucalyptus sp. Stands

The present study aims: (a) to assess the correlations between forest stand characteristics (viz., basal area, dominant height, and volume) and the reflectance values derived from Landsat 5 TM spectral bands as well as from vegetation indices and (b) to understand how Eucalyptus sp. stand age influences these correlations. Sampling data comprised a set of 35 permanent plots from a forest inventory conducted annually between 2006 and 2011. Spectral data were derived from Landsat 5 TM images. The results showed that TM4 and TM5 spectral bands, as well as vegetation indices ND54 and TM5/4, were better correlated with basal area and volume, while the TM2 spectral band was better correlated with dominant height. Eucalyptus sp. stand age directly influenced the correlations between spectral data and forest stand characteristics, and could not be disregarded in the spectral characterization of the forest variables.

Riqueza e diversidade de espécies em um fragmento de campo cerrado por meio de krigagem ordinária

The objective of this work was to analyze the spatial distribution and the behavior of species richness and diversity in a shrub savanna fragment, in 2003 and 2014, using ordinary kriging, in the state of Minas Gerais, Brazil. In both evaluation years, the measurements were performed in a fragment with 236.85 hectares, in which individual trees were measured and identified across 40 plots (1,000 m 2 ). Species richness was determined by the total number of species in each plot, and diversity by the Shannon diversity index. For the variogram study, spatial models were fitted and selected. Then, ordinary kriging was applied and the spatial distribution of the assessed variables was described. A strong spatial dependence was observed between species richness and diversity by the Shannon diversity index (<25% spatial dependence degree). Areas of low and high species diversity and richness were found in the shrub savanna fragment. Spatial distribution behavior shows relative stability regarding the number of species and the Shannon diversity index in the evaluated years.

Water Availability Drives Gradients of Tree Diversity, Structure and Functional Traits in the Atlantic-Cerrado-Caatinga Transition, Brazil

Aims Climate and soil are among the most important factors determining variation in tree communities, but their effects have not been thoroughly elucidated to date for many vegetation features. In this study, we evaluate how climate and soil gradients affect gradients of vegetation composition, species diversity and dominance, structure and functional traits (seed mass and wood density) using over 327 000 trees in 158 sites distributed along environmental gradients in the transitions among the Atlantic forest, Cerrado and Caatinga in Minas Gerais State (MG), Brazil (nearly 600 000 km 2). Methods Gradients in species, genus and family abundance in addition to basal area, stem density, species diversity (Fishers alpha), dominance percentage, seed mass and wood density were correlated using multiple regressions with environmental variables, as summarized in four principal component analysis axes (two climatic - precipitation seasonality and temperature range - and two edaphic - soil fertility and soil moisture). Additionally, ordinary kriging maps were used to better illustrate the gradients. Important Findings Multiple regression models indicate that all variables but dominance percentage were affected by one or more of the environmental gradients, but the average R 2 was low (26.25%). Kriging maps reinforced the patterns observed in the regression models. Precipitation seasonality and soil moisture gradients were the most important gradients affecting vegetation features. This finding suggests that water availability is an important determinant of vegetation features in these vegetation transitions.

CHARACTERIZING LANDSCAPE SPATIAL HETEROGENEITY USING SEMIVARIOGRAM PARAMETERS DERIVED FROM NDVI IMAGES

The authors are grateful to the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES), Department of Forest Science of the Federal University of Lavras (UFLA) and the ONF Brazil group for supporting this work.