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Master's Dissertation
DOI
Document
Author
Full name
Humberto Tadeu Menecheli Filho
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2019
Supervisor
Committee
Silva, Luciana Duque (President)
Behling, Maurel
Bernardes, Marcos Silveira
Tonini, Helio
Title in Portuguese
Efeito do desbaste na interação entre os componentes de um sistema silvipastoril
Keywords in Portuguese
Eucalipto
Manejo florestal
Produtividade
Sistema agroflorestal
Abstract in Portuguese
O desbaste é uma técnica silvicultural tradicional e amplamente adotada, consiste na remoção de uma porção da área basal do povoamento florestal com o principal objetivo de reduzir a competição por recursos e concentrar o crescimento nas árvores alvo da colheita final, porém em sistemas agroflorestais essa técnica também beneficia outros componentes do sistema, se bem planejada. O objetivo deste estudo foi definir uma estratégia de desbaste em sistemas silvipastoris em áreas de déficit hídrico. O experimento foi conduzido em uma área plantada em 2011 com Eucalyptus urophylla x grandis, espaçamento 9 m por 3 m, em consorcio com Brachiaria brizantha marandu (plantada em 2013), implantada em 2013, localizado no município de Correntina - BA. Em 2015, o experimento foi instalado no delineamento de blocos casualizados, com três blocos e seis tratamentos. As intensidades de desbastes foram as seguintes (representada pela porcentagem de árvore removida por renque): 0%-0%, 50%-33%, 100%-0%, 50%-50%, 50%-66%, 100%-33%. A parcela total tem formato retangular e tamanho de 100 por 54 m, abrangendo seis renques, e a parcela útil de tamanho de 75 por 18 metros e abrangendo dois renques. Foram realizadas cinco avaliações, em intervalos de três meses, do componente arbóreo, sendo mensurados o DAP, altura, altura da copa, área da copa e índice de área foliar. Foram realizadas quatro avaliações, repetidas a cada três meses, de biomassa da pastagem e umidade do solo, para a pastagem foram realizadas nove amostras sistemáticas por parcela em uma área de 0,25 m2 e cortes realizados na altura de 20 cm. Para o solo foram coletadas duas amostras nas profundidades de 20 e 40 cm do solo, na mesma localidade onde foram realizadas a coleta de amostras de pastagem. A avaliação do componente arbóreo mostrou que o DAP, comprimento da copa em relação à altura, área da copa tiveram resposta positiva com o desbaste, porém a altura mostrou uma resposta negativa com o desbaste. A área basal do sistema silvipastoril e a produção de biomassa da planta forrageira apresentaram relação inversa, pois o sombreamento do componente arbóreo tem relação positiva com a área basal e a produção de pastagem tem relação negativa com o sombreamento. A produção de matéria seca da pastagem teve uma resposta positiva ao desbaste quando comparado com o tratamento sem desbaste. As densidades de 370 arv.ha-1 e 142 arv.ha-1 resultaram em menor umidade do solo. O desbaste teve efeito positivo na conservação de água por diminuir a evapotranspiração total do componente arbóreo, porém altas intensidades de desbaste diminuíram a umidade do solo, devido ao aumento da evapotranspiração do solo e da pastagem. O desbaste mais adequado foi de intensidades moderadas, com área basal residual entre 4 m2/ha na idade de 7 anos e arranjos com um coeficiente de retangularidade menor que 2.
Title in English
Effect of thinning on the interaction between the components of a Silvopastural System
Keywords in English
Agroforestry system
Eucalyptus
Forest management
Thinning
Abstract in English
Thinning is a traditional and widely adopted silvicultural technique, consisting of the removal of a portion of the basal area of the forest stands with the main objective of reducing the competition for resources and concentrating the growth in the final harvest trees. The adoption of silvopastoral systems has been growing in Brazil and with this, the opportunity to produce lumber, but little information is available on the management of these types of crops. The objective of this study was to define a strategy of thinning silvopastoral systems in areas of water deficit, taking into account the production of sawn wood and pasture. The experiment was conducted in an area planted in 2011 with Eucalyptus urophylla x grandis, spaced 9 m by 3 m, in a consortium with Brachiaria brizantha marandu (planted in 2013), established in 2013, located in the municipality of Correntina - BA. In 2015, the experiment was installed in a randomized complete block design with three blocks and six treatments. The treatments and intensities of thinning were (represented as percentage of trees removed by rows): 0% -0%, 50% -33%, 100% -0%, 50% -50%, 50-66%, 100% -33%. The total plot has a rectangular shape and size of 100 by 54 meters, covering six rows, and the measurement plot size of 75 by 18 meters and comprising two rows. Five evaluations were performed, at three month intervals, of the tree component, and the DBH, height, crown height, crown area and leaf area index were measured. Four evaluations, repeated every three months, of pasture biomass and soil moisture were carried out. Nine systematic samples were taken per plot in an area of 0.25 m2 and cuts were performed at a height of 20 cm. For the soil, two samples were collected at depths of 20 and 40 cm from the soil, in the same locality where the grazing samples were collected. The evaluation of the tree component showed that the DBH, canopy length in relation to height, crown area had a positive response with thinning, but height showed a negative response to thinning. The basal area of the silvopastoral system and the biomass production of the forage plant resulted an inverse relation, since the shading of the tree component has a positive relation with the basal area and the pasture production has negative relation with the shading. The dry matter production of the pasture had a positive response to thinning when compared to the treatment without thinning. The densities of 370 arv.ha-1 and 142 arv.ha-1 resulted in lower soil moisture. Thinning had a positive effect on water conservation by reducing total evapotranspiration of the tree component, but high thinning intensities have reduced soil moisture due to increased evapotranspiration of soil and pasture. The most adequate thinning for silvopastural system is of medium intensities, with a retained basal area around 4 m2/ha and arrangements with a rectangular coefficient lower than 2.
 
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Publishing Date
2019-08-16
 
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