INFLU\ucaNCIA DO FOGO NO BANCO DE SEMENTES DO SOLO EM FLORESTA ESTACIONAL SEMIDECIDUAL

This study was carried out in a fragment called "Reserva da Biologia", which belongs to the Universidade Federal de Vi\ue7osa, in Minas Gerais State, Brazil (20\ub035'-28\ub050'S e 42\ub045'-43\ub000'W), where 10 plots of 5 x 5 m plots, 1m away from each other, were set up. A controlled burning was performed on the plots, following the wind-driven fire technique, according to the slope orientation. The objective was to characterize the soil seed of the tree community before and after fire, in order to verify the effects of such discontinuance on both population density and floristic composition. In the centre of each plot, one 40 x 25 cm soil sampling was collected, from the leaf litter downward 5cm deep. One day after the soil sampling the plots underwent controlled burning. New soil samplings were done immediately after burning, following the previous methodology. It was counted 528 and 429 seedlings emerging from the soil seed bank before and after the fire, respectively. Such plants were of 23 species and 14 botanical families, from which Melastomataceae, Asteraceae and Urticaceae stood out. There was no meaningful reduction in the species richness or in the density of individuals of the populations between both samplings. The floristic similarity was 34 %. Miconia cinnamomifolia and Leandra purpurascens were the most frequent/abundant species. Pioneer species stood out making up 44 and 40 % of the species found in the area before and after fire, respectively.Este estudo foi realizado no fragmento "Reserva da Biologia", situado na Universidade Federal de Vi\ue7osa, Minas Gerais, (20\ub035'-28\ub050'S e 42\ub045'-43\ub000'W) onde foram instaladas 10 parcelas de 5 x 5 m interdistantes em 1 m. Foi realizada uma queima controlada nas parcelas instaladas, utilizando a t\ue9cnica do fogo a favor do vento, obedecendo ao sentido do aclive. O objetivo foi caracterizar o banco de sementes do solo antes e depois do fogo, para verificar os efeitos desse dist\ufarbio na densidade das popula\ue7\uf5es e na composi\ue7\ue3o flor\uedstica da comunidade vegetal. No centro de cada parcela foi coletada uma amostra de solo de 40 x 25 cm, a partir da superf\uedcie da serapilheira at\ue9 5 cm de profundidade. Um dia ap\uf3s a coleta das amostras de solos as parcelas foram submetidas \ue0 queima controlada. Imediatamente ap\uf3s a queima foram realizadas novas coletas de solo seguindo a mesma metodologia adotada anteriormente. Foram obtidas 528 e 429 sementes germinadas das amostras do banco de sementes do solo antes e ap\uf3s o fogo, respectivamente, pertencentes a 23 esp\ue9cies de 14 fam\uedlias bot\ue2nicas, sendo as mais representativas Melastomataceae, Asteraceae e Urticaceae. Entre as duas amostragens (antes e ap\uf3s o fogo) n\ue3o houve redu\ue7\ue3o significativa da riqueza de esp\ue9cies e a similaridade flor\uedstica foi de 34 %. Miconia cinnamomifolia e Leandra purpurascens foram as esp\ue9cies mais abundantes nas duas amostragens. As esp\ue9cies pioneiras se destacaram com 44 e 40 % das esp\ue9cies presentes no banco de sementes antes e ap\uf3s o fogo, respectivamente

STUDY OF FIRE BEHAVIOR ON A PART OF SEMIDECIDUOUS SEASONAL FOREST IN VI\uc7OSA, MINAS GERAIS

O objetivo do presente estudo foi avaliar o comportamento do fogo em um trecho de Floresta Estacional Semidec\ueddua, usando as vari\ue1veis: intensidade do fogo, tempo de queima, material combust\uedvel, poder calor\uedfico e calor liberado por \ue1rea. Foram instaladas 10 parcelas de 5 x 5 m interdistantes em 1 m, perfazendo um total de 250 m2, em um fragmento denominado \u201cReserva da Biologia\u201d, pertencente \ue0 Universidade Federal de Vi\ue7osa, Minas Gerais, (20\uba35\u2019-28\uba50\u2019S e 42\uba45\u2019-43\uba00\u2019W) onde foi realizada a queima controlada utilizando a t\ue9cnica do fogo a favor do vento, obedecendo ao sentido do aclive. Determinouse a quantidade de mat\ue9ria seca, velocidade de propaga\ue7\ue3o do fogo, intensidade, calor liberado e poder calor\uedfico. O tempo de dura\ue7\ue3o da queima variou entre as parcelas de 3\u201930\u201d a 9\u201918\u201d. A velocidade do vento, temperatura e umidade relativa do ar no dia da queima permaneceram constantes em todas as parcelas, apresentando valores de 3,5 m s-1 Norte, 20\ubaC e 79%, respectivamente. Os par\ue2metros do comportamento do fogo variaram entre as parcelas em: 0,32 a 1,10 kg m-2 para material combust\uedvel, 11,94 a 75,79 Kcal s-1 m-1 para a intensidade de queima e 1111 a 3789 Kcal m-2 para o calor liberado por \ue1rea. Os valores m\ue9dios para velocidade de propaga\ue7\ue3o e poder calor\uedfico foram 0,017 m s-1 e 4411 Kcal Kg-1, respectivamente. As condi\ue7\uf5es clim\ue1ticas de Vi\ue7osa em 2005 foram at\uedpicas em rela\ue7\ue3o aos outros anos, n\ue3o apresentando nenhum m\ueas seco. Esta condi\ue7\ue3o interferiu nos par\ue2metros do comportamento do fogo, fazendo com que a queima fosse classificada como de baixa intensidade.The purpose of this study was to evaluate the fire behavior on a part of Semideciduous Seasonal Forest, using the variables: fire intensity, burning time, fuel, heat content and heat released. Ten plots of 5 by 5 meters were used , totalizing 250 m2, and the distance between each plot was 1 meter in a place named \u201cReserva da Biologia\u201d property of Universidade Federal de Vi\ue7osa, Minas Gerais, (20\uba35\u2019-28\uba50\u2019S e 42\uba45\u2019-43\uba00\u2019W) . In this place a control burning was performed using strip headfire technique, obeying the slope direction. The amount of local dry matter, fire propagation velocity, intensity, heat released and heat content were measured. The time duration of the burning ranged between plots of 3\u201930 \u201cto 9\u201918\u201d. Wind velocity, temperature, relative humidity were constant in all plots, with values 3, 5 m s-1 North, 20\uba C and 79% respectively. The values found for fire behavior variables ranged between plots: from 0, 32 to 1, and 10 Kg m-2 for fuel, from 11, 94 to 75,79 Kcals-1m-1 for burning intensity and from 1111 to 3789 Kcal m-2 for heat released. The average values for rate of spread and heat released were 0,017 m s-1 and 4411 Kcal Kg-1, respectively. In the year 2005, the weather conditions were atypical comparing to another years in Vi\ue7osa, witch in every month occurs a certain amount of rain. This fact had interference in the fire behavior parameters, for that reason the burning were classified as low intensity

INFLU\ucaNCIA DO FOGO NO BANCO DE SEMENTES DO SOLO EM FLORESTA ESTACIONAL SEMIDECIDUAL

This study was carried out in a fragment called "Reserva da Biologia", which belongs to the Universidade Federal de Vi\ue7osa, in Minas Gerais State, Brazil (20\ub035'-28\ub050'S e 42\ub045'-43\ub000'W), where 10 plots of 5 x 5 m plots, 1m away from each other, were set up. A controlled burning was performed on the plots, following the wind-driven fire technique, according to the slope orientation. The objective was to characterize the soil seed of the tree community before and after fire, in order to verify the effects of such discontinuance on both population density and floristic composition. In the centre of each plot, one 40 x 25 cm soil sampling was collected, from the leaf litter downward 5cm deep. One day after the soil sampling the plots underwent controlled burning. New soil samplings were done immediately after burning, following the previous methodology. It was counted 528 and 429 seedlings emerging from the soil seed bank before and after the fire, respectively. Such plants were of 23 species and 14 botanical families, from which Melastomataceae, Asteraceae and Urticaceae stood out. There was no meaningful reduction in the species richness or in the density of individuals of the populations between both samplings. The floristic similarity was 34 %. Miconia cinnamomifolia and Leandra purpurascens were the most frequent/abundant species. Pioneer species stood out making up 44 and 40 % of the species found in the area before and after fire, respectively.Este estudo foi realizado no fragmento "Reserva da Biologia", situado na Universidade Federal de Vi\ue7osa, Minas Gerais, (20\ub035'-28\ub050'S e 42\ub045'-43\ub000'W) onde foram instaladas 10 parcelas de 5 x 5 m interdistantes em 1 m. Foi realizada uma queima controlada nas parcelas instaladas, utilizando a t\ue9cnica do fogo a favor do vento, obedecendo ao sentido do aclive. O objetivo foi caracterizar o banco de sementes do solo antes e depois do fogo, para verificar os efeitos desse dist\ufarbio na densidade das popula\ue7\uf5es e na composi\ue7\ue3o flor\uedstica da comunidade vegetal. No centro de cada parcela foi coletada uma amostra de solo de 40 x 25 cm, a partir da superf\uedcie da serapilheira at\ue9 5 cm de profundidade. Um dia ap\uf3s a coleta das amostras de solos as parcelas foram submetidas \ue0 queima controlada. Imediatamente ap\uf3s a queima foram realizadas novas coletas de solo seguindo a mesma metodologia adotada anteriormente. Foram obtidas 528 e 429 sementes germinadas das amostras do banco de sementes do solo antes e ap\uf3s o fogo, respectivamente, pertencentes a 23 esp\ue9cies de 14 fam\uedlias bot\ue2nicas, sendo as mais representativas Melastomataceae, Asteraceae e Urticaceae. Entre as duas amostragens (antes e ap\uf3s o fogo) n\ue3o houve redu\ue7\ue3o significativa da riqueza de esp\ue9cies e a similaridade flor\uedstica foi de 34 %. Miconia cinnamomifolia e Leandra purpurascens foram as esp\ue9cies mais abundantes nas duas amostragens. As esp\ue9cies pioneiras se destacaram com 44 e 40 % das esp\ue9cies presentes no banco de sementes antes e ap\uf3s o fogo, respectivamente