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

Abstract

-This study aimed to verify the differences in radiation intensity as a function of distinct relief exposure surfaces and to quantify these effects on the leaf area index (LAI) and other variables expressing eucalyptus forest productivity for simulations in a process-based growth model. The study was carried out at two contrasting edaphoclimatic locations in the Rio Doce basin in Minas Gerais, Brazil. Two stands with 32-year-old plantations were used, allocating fixed plots in locations with northern and southern exposure surfaces. The meteorological data were obtained from two automated weather stations located near the study sites. Solar radiation was corrected for terrain inclination and exposure surfaces, as it is measured based on the plane, perpendicularly to the vertical location. The LAI values collected in the field were used. For the comparative simulations in productivity variation, the mechanistic 3PG model was used, considering the relief exposure surfaces. It was verified that during most of the year, the southern surfaces showed lower availability of incident solar radiation, resulting in up to 66% losses, compared to the same surface considered plane, probably related to its geographical location and higher declivity. Higher values were obtained for the plantings located on the northern surface for the variables LAI, volume and mean annual wood increase, with this tendency being repeated in the 3PG model simulations.Keywords: Terrain exposure surfaces; LAI; Global solar radiation. MODELAGEM E SIMULAÇÃO DA INFLUÊNCIA DO RELEVO EM FLORESTAS DE EUCALIPTO: INTERAÇÃO ENTRE A IRRADIÂNCIA SOLAR E PRODUTIVIDADERESUMO -Este trabalho teve por objetivo verificar as diferenças da intensidade da radiação frente às distintas faces de exposição do relevo e quantificar estes efeitos no índice de área foliar (IAF) e outras variáveis que expressam a produtividade de florestas de eucalipto, para simulações em um modelo de crescimento de plantios florestais. O estudo foi realizado em duas localidades de contrastes edafoclimáticos, localizadas na bacia do Rio Doce, MG. Trabalhou-se em dois talhões com plantios em idades de 32 meses, tendo sido alocadas parcelas fixas em locais com a face de exposição norte e sul. Os dados meteorológicos foram obtidos de duas estações meteorológicas automáticas localizadas próximas às localidades de estudo. A radiação solar foi corrigida em função das inclinações e faces de exposição do terreno, tendo em vista que esta é mensurada no plano, perpendicularmente à vertical do local. Foram utilizados os valores do IAF coletados em campo. Para as simulações comparativas na variação da produtividade, utilizou-se o modelo mecanístico 3PG considerando as faces de exposição do relevo. Verificou-se que na maior parte do ano, as faces sul apresentaram menor disponibilidade de radiação solar incidente resultando em perdas de até 66% em comparação à mesma superfície considerada plana, podendo

Edaphic and physiographic attributes and death of cacao trees in drought years

“…The higher plant mortality on plots with north-facing slopes can be because, in the southern hemisphere, this direction receives greater solar radiation than the south-facing slopes. This is evident in the findings of Rody et al (2016), who studied the effect of solar radiation intensity on the productivity of 3 mo months of the year (November, December, and January) the radiation was slightly higher on the south-facing slopes than on the north-facing slopes; in two months of the year (February and October) the radiation was similar between the directions, being slightly higher on the north-facing slopes; and in the other seven months of the year the radiation was much higher on the north-facing slopes vs. the south-facing slopes, with the maximum differences being reached in the months of June and July, which justified the higher forest production on the north-facing slopes. It is emphasized that greater radiation for plant production is positive when there is no water deficit, but in conditions of prolonged drought, greater radiation means greater damage to crops and even plant death as shown in this study.…”

Uso de redes neurais artificiais na predição de parâmetros e calibração do modelo 3-PG

“…Mas, além disso, o sistema fotossintético, representado pelo A f no modelo, também é determinado pela qualidade do sítio (MEGOWN; WEBSTER; JACOBS, 1999). O A f tem forte relação com a precipitação pluviométrica anual média (ELLIS; HATTON, 2008), é responsável pela determinação da condutância do dossel (WARING; LANDSBERG, 2011) e também pode ser influenciada pela altitude (RODY et al, 2016). Dessa forma, sua variação no tempo e espaço pode colaborar na predição das variáveis.…”