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Abstract(s)
Entender as caracteristícas dos combustíveis juntamente com o papel benéfico do pastoreio é uma ferramenta essencial na gestão da vegetação de áreas propensas a incêndios. Objetivou-se com este estudo caracterizar o material combustível superficial, a partir da sua quantificação e classificação em função da perigosidade em quatro povoamentos florestais (Pinhal manso, Castinçal, Sobreiral e Carvalhal) para o inverno e verão, e também avaliar o efeito do pastoreio de caprinos na redução dos combustíveis em dois deles (Sobreiral e Carvalhal) no Nordeste de Portugal. Analisou-se a quantificação do material combustível por meio da amostragem superficial de 1m², sendo realizadas dez coletas para cada estação de interesse, em cada povoamento. A classificação baseou-se em seus diâmetros, onde < 1cm sendo perigosos, > 1cm semi-perigosos e o material verde. A umidade foi avaliada por pesagem pré e pós secagem em estufa, e os mapas confeccionados com base nas coordenadas das respectivas coletas. A cobertura vegetal foi avaliada pelo método da linha de intercepção, através de três transeptos de 20 metros aleatórios para cada povoamento na análise dos combustíveis, e cinco transeptos fixos para a análise do efeito do pastoreio. Em cada transepto mediu-se o comprimento da intercepção na vegetação ao longo de 20 metros, distinguindo-se as herbáceas como um todo e as arbustivas por espécie, mediu-se as alturas modais de todas as intercepções em vegetação arbustiva. A avaliação do biovolume obteve-se através do produto da cobertura vegetal arbustiva em percentagem pela altura. A biomassa herbácea avaliou-se pelo método de corte e pesagem em quadrados de 0.50 m de lado. O pastoreio caprino foi analisado com base no número de animais e horas de pastoreio. O Castanheiro é o que possui a maior quantidade de material combustível para o inverno, com 17,764 ton/ha, e o menor para o verão com 4,081 ton/ha, composto principalmente pelos materiais perigosos. O Pinheiro apresentou o maior valor médio de umidade para o inverno (149,65%), e uma das menores para o verão (7,84%) apresentando a maior amplitude dentre os povoamentos. O Carvalho apresentou o menor teor de umidade para o verão (6,87%), o maior valor de biovolume, 4 695,952 m³/ha, e também o maior valor para o coberto vegetal arbustivo (51,915%). O pastoreio caprino apresentou efeito positivo na redução da carga combustível no povoamento de Sobreiral, pois realiza uma redução de 78,84% do biovolume, como também no Carvalhal, com 35,14% de redução. O Castanheiro apresenta a maior quantidade de material combustível para o inverno. O Sobreiro apresenta 99,80% de seus combustíveis como material perigoso. O Carvalho apresenta o menor teor de umidade para o verão e o maior valor de biovolume. O pastoreio caprino possui efeito positivo na redução da carga combustível para o Sobreiral e para o Carvalho americano.
Understanding the characteristics of fuels along with the beneficial role of grazing is an essential tool in managing the fire-prone vegetation areas The objective of this study was to characterize the surface combustible material, from its quantification and classification as a function of danger in four forest stands (Pinhal manso, Castinçal, Sobreiral and Carvalhal) for winter and summer, and also evaluate the grazing of goats effect in the reduction of fuel in two of them (Sobreiral and Carvalhal) in the North East of Portugal. The combustible material quantification was analyzed through 1m² surface sampling, with ten collections being carried out for each station of interest, in each season. The classification was based on their diameters, which < 1cm being hazardous, > 1cm semi-hazardous and the green material. Moisture was evaluated by weighing before and after drying in an oven, and the maps were made based on the sampling points coordinates. The vegetation cover was evaluated using the intercept line method, in which, three random transepts 20 meters in length were defined for each season in the analysis of fuels, and five fixed transepts for the grazing effect analysis. In each transept, the length of the intercept in the vegetation was measured along 20 meters, distinguishing the herbaceous as a whole and the shrubs by species, the modal heights of all the intercepts in the shrub vegetation were measured. Biovolume evaluation was obtained through the product of the shrub vegetation cover in percentage by height. The herbaceous biomass was evaluated using the cutting and weighing in squares of 0.50 m side method. Goat grazing was analyzed based on number of animals and grazing hours. The chestnut tree has the largest amount of combustible material for winter, with 17,764 ton/ha, and the smallest for summer, with 4,081 ton/ha, mainly composed of hazardous materials. Pine presented the highest average moisture value for the winter (149.65%), and one of the lowest for the summer (7.84%), presenting the greatest amplitude among the stands. Oak presented the lowest moisture content for the summer (6.87%), the highest biovolume value, 4 695.952 m³/ha, and also the highest value for shrub vegetation cover (51.915%). Goat grazing had a positive effect on reducing the fuel load in the cork oak forest, as it reduced the biovolume by 78.84%, as well as in the oak forest, with a 35.14% reduction. Chestnut has the greatest amount of combustible material for winter. Cork oak presents 99.80% of its fuels as hazardous material. Oak has the lowest moisture content for the summer and the highest biovolume value. Goat grazing has a positive effect on reducing the fuel load for cork oak and American oak.
Understanding the characteristics of fuels along with the beneficial role of grazing is an essential tool in managing the fire-prone vegetation areas The objective of this study was to characterize the surface combustible material, from its quantification and classification as a function of danger in four forest stands (Pinhal manso, Castinçal, Sobreiral and Carvalhal) for winter and summer, and also evaluate the grazing of goats effect in the reduction of fuel in two of them (Sobreiral and Carvalhal) in the North East of Portugal. The combustible material quantification was analyzed through 1m² surface sampling, with ten collections being carried out for each station of interest, in each season. The classification was based on their diameters, which < 1cm being hazardous, > 1cm semi-hazardous and the green material. Moisture was evaluated by weighing before and after drying in an oven, and the maps were made based on the sampling points coordinates. The vegetation cover was evaluated using the intercept line method, in which, three random transepts 20 meters in length were defined for each season in the analysis of fuels, and five fixed transepts for the grazing effect analysis. In each transept, the length of the intercept in the vegetation was measured along 20 meters, distinguishing the herbaceous as a whole and the shrubs by species, the modal heights of all the intercepts in the shrub vegetation were measured. Biovolume evaluation was obtained through the product of the shrub vegetation cover in percentage by height. The herbaceous biomass was evaluated using the cutting and weighing in squares of 0.50 m side method. Goat grazing was analyzed based on number of animals and grazing hours. The chestnut tree has the largest amount of combustible material for winter, with 17,764 ton/ha, and the smallest for summer, with 4,081 ton/ha, mainly composed of hazardous materials. Pine presented the highest average moisture value for the winter (149.65%), and one of the lowest for the summer (7.84%), presenting the greatest amplitude among the stands. Oak presented the lowest moisture content for the summer (6.87%), the highest biovolume value, 4 695.952 m³/ha, and also the highest value for shrub vegetation cover (51.915%). Goat grazing had a positive effect on reducing the fuel load in the cork oak forest, as it reduced the biovolume by 78.84%, as well as in the oak forest, with a 35.14% reduction. Chestnut has the greatest amount of combustible material for winter. Cork oak presents 99.80% of its fuels as hazardous material. Oak has the lowest moisture content for the summer and the highest biovolume value. Goat grazing has a positive effect on reducing the fuel load for cork oak and American oak.
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Keywords
Redução do risco de incêndio Limpeza biológica Sub-bosque Sistemas silvipastoris