Saldo de radiação em plantios de eucalipto em áreas de relevo ondulado

Abstract

RESUMO -O conhecimento detalhado de radiação solar total que incide sobre uma região é importante para o planejamento das atividades florestais. Poucos trabalhos têm considerado a topologia da região para determinar o saldo de radiação solar (Rn), o que pode levar a erros significativos de estimativa dessa variável, dependendo do tipo de relevo predominante na região. Este estudo teve como objetivo estimar o Rn em plantios de eucalipto, levando-se em consideração a exposição do terreno em plantios florestais de eucalipto, bem como comparar essas estimativas com a estimativa em condições de topografia plana. A simulação foi realizada para os anos de 2001 e 2002, em uma microbacia do rio Doce. As encostas com orientações para o norte, nordeste e noroeste apresentaram aumentos do Rn em relação à estimativa da superfície plana, pelo fato de que, nessa época do ano, o sol, em seu movimento aparente, encontra-se ao norte da microbacia. Entretanto, as encostas com orientações para o sul, sudeste e sudoeste tiveram diminuição do Rn quando comparadas com as condições de topografia plana. A inclinação das encostas influenciou a magnitude das diferenças de ganho e perda de Rn. Quanto maiores as inclinações das encostas voltadas para o norte, noroeste e nordeste, maiores as variações, atingindo valores percentuais de aumento do Rn de até 40%, em julho. Portanto, verificou-se existir importante influência das diferentes inclinações e orientações das encostas nos totais diários do Rn.Palavras-chave: Eucalipto, saldo de radiação e SIG. NET RADIATION FOR EUCALYPT PLANTATIONS IN AREAS WITH UNDULATED RELIEFABSTRACT -The detailed knowledge of the total solar radiation that reaches a surface is fundamental for the planning of the forest activities. A few research works cited in the literature have considered the topographic effect of the region to determine the solar radiation balance (Rn), in which, depending on the predominant topographic relief of the region, significant errors can be obtained. This study was carried out to estimate the Rn considering the slope aspect of the terrain for eucalypt forest plantation, and to compare this estimates with and flat terrain areas. The simulation was carried out for the years of 2001 and 2002 in Rio Doce watershed. The hillsides with northward, northeast and the northwest orientation presented increases in Rn in relation to the estimate for flat horizontal surface, because at this time of the year, the sun, in its apparent movement, tape place north of the watershed. However, the hillsides with south, southeast and southwest orientation, presented reduction in Rn when compared with the conditions of flat topography. The hillsides inclination influenced in the magnitude of the differences between gain of energies and loss Rn. The hillsides inclinations faced northward, the northwest and northeast, had greaters variations, witch increased Rn of up to 40%, in July. It was demonstrated that exist important influence of the different slopes and aspects of the hillsides terrain over the total d...

Modeling and Simulation of Relief Influence on Eucalyptus Forests: Interaction Between Solar Irradiance and Productivity

“…Practically no differences were verified in the magnitude of the radiation gains between the northern surfaces in both locations of the stands, since the Modeling and simulation of relief influence... difference in declivity between the locations was of only one degree. This response pattern was also observed by Facco et al, (2009) in a micro-basin with undulated relief located in the Rio Doce basin.…”

“…Few studies have been conducted considering that relief can lead to error estimates in solar radiation balance (MEFTI et al, 2003;FACCO et al, 2009). …”

How environmental factors condition natural regeneration in the altitudinal gradient of a montane rainforest

“…The luminosity in the valley varies according to the orientation of the slope of the terrain, in uencing the local microclimate, patterns of deposition and germination of propagules, and on the establishment and growth of certain species (Quadros et al 2013;Morel et al 2015). In the valley, the luminous incidence on the North and Northeast slopes, especially in winter, is more perpendicular and constant, implying a greater amount of energy in these areas (Facco et al 2009). In these slopes, with the exception of quota E1, the lowest absolute density values were recorded, indicating that the highest luminosity may be affecting the establishment of species belonging to the mature stages of succession, predominant in the valley (Bovolenta et al 2021).…”

Physical Factors of the Landscape Which Condition Spontaneous Forest Restoration

“…Moreover, in the southern hemisphere, slopes exposed to the south present better vegetation growth (OLIVEIRA et al, 1995;SILVEIRA;SILVA, 2010) and a higher number of forest fragments (MARQUES et al, 2004) than those facing north because the sun's rays tend to intercept the surfaces facing north, while they are more tangential to those facing south (FERREIRA et al, 2005). This difference causes the slopes facing north to receive a more considerable amount of solar radiation (FACCO et al, 2009), which causes a more significant loss of humidity through evapotranspiration as well as physical and chemical differences in the soil (FERREIRA et al, 2005).…”