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AbstractThe spatial and temporal distributions of vegetation can be influenced by edaphic and environmental factors as well as disturbances. The present study was undertaken to characterize the distribution and spatial dependence of species diversity in a fragment of semideciduous seasonal forest after a disturbance event by fire and to identify changes during natural regeneration. The fire, occurred in 1999, and surveys were undertaken in 2000, 2005 and 2014 in 26 geo-referenced plots (400 m²) distributed along two transects. The Fire Damage Index (FDI) in each plot was based on a scale from 0 to 5, and all of the arboreal individuals with diameters at breast height (DBH) ≥ 5 cm were identified in each plot. Species diversity was calculated using the Shannon index (H'), and species richness (S) was estimated using species accumulation curves; variations between the surveys compared based on the means and standard errors. The S, H' and FDI data were submitted to non-spatial exploratory and geostatistical analyses. After adjusting the semivariograms, the levels of spatial dependence were classified, and interpolation of the variables values were performed using ordinary kriging to characterize their spatial distributions in the form of maps. Spatial analysis was used to identify and characterize differences between the post-fire surveys in terms of the configurations of the arboreal community. The fire event influenced the spatial and temporal structures of the variables S and H'. These variables showed spatial dependence and aggregated distributions, with reduction in the distance under spatial influences and a uniformity of individuals distribution in the forest fragment at the different surveys. This research characterized the distribution and spatial dependence of the variables S and H' in a forest fragment after a fire event and the alterations in the arboreal community structure during natural regeneration.
ResumenLa distribución espacial y temporal de la vegetación esta influenciada por factores edáficos, ambientales y alteraciones. En ese contexto, el objetivo del estudio fue caracterizar el patrón de distribución y la dependencia espacial de la diversidad de especies en un fragmento de bosque estacional semideciduo, donde ocurrió un incendio, e identificar alteraciones a lo largo del proceso de regeneración natural. El incendio ocurrió en 1999, y en 2000, 2005 y 2014, se hicieron inventarios florísticos en 26 parcelas (400 m2) georreferenciadas y distribuidas en dos transectos. El índice de daño del fuego (IDF) se evaluó en cada parcela con base en una escala de 0 a 5. En cada inventario se identificaron las plantas arbóreas con diámetro a altura de pecho (DAP) ≥ 5 cm, calculando la diversidad de especies con base en el índice de Shannon (H') y estimando la riqueza de especies (S). Esas variaciones fueron analizadas utilizando la curva de acumulación de especies, y la variación entre inventarios fue comparada con base en las medias y el error estándar. Los datos de S, H' e IDF fueron sometidos a análisis exploratorio no espacial y a análisis geoestadístico. Después del ajuste de los semivariogramas, se clasificó el nivel de dependencia espacial y se hizo la interpolación de datos por Krigeado ordinario para caracterizar, en mapas, el patrón de distribución espacial de esas variables. Se encontró diferencia entre los inventarios realizados después del incendio, como en la configuración de la comunidad arbórea, por lo que el análisis espacial permitió identificar y caracterizar este hecho. El incendio afectó la estructura espacial y temporal de las variables S y H'. Estas variables presentan dependencia espacial y la distribución agregada, con distancias más pequeñas bajo influencia espacial, y la uniformidad de la distribución de los individuos en el fragmento de bosque durante las distintas etapas. Por último, se caracterizó la distribución y la dependencia espacial de las variables S e H 'en un fragmento de bosque después de un incendio, y las alteraciones en la estructura de la comunidad arbórea durante la regeneración natural.
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ABSTRACT: Lecanicillium fungicola, which causes Dry bubble disease, induces infections and inflicts major losses in champignon production. The control can be managed through measures of hygiene and use of fungicides; however, in Brazil there are no registered products. This study aimed to estimate the influence of various essential oils extracted from Melissa officinalis, Thymus vulgaris, Origanum vulgare, Eucalyptus globulus, Cinnamomum zeylanicum and Syzygium aromaticum on the in vitro development and their uses. Therefore, analysis was performed of the L. fungicola isolates in vitro and the best oils were tested in vivo. Besides, the Agaricus bisporus - L. fungicola interaction was confirmed by scanning electron microscopy (SEM). Cinnamon and clove oils in concentrations of 0.4% and thyme oil of 0.8% were identified as good growth inhibitors of the pathogenic mycelium. Effective inhibition of the conidial germination was seen in all concentrations by cinnamon oil, and by clove and thyme oils only at 0.4% and 0.8%, respectively. When the essential oils were applied post-infestation in the in vivo experiments the incidence of the disease in the mushrooms was much lower. From the SEM it was clear that 19 hours after the inoculation of A. bisporus with L. fungicola, the spores had already completely germinated, revealing the presence of the infection. Therefore, the findings of this study indicated that the oil extracts of cinnamon, clove and thyme are potential and efficient alternatives in the control of dry bubble disease.
RESUMO: A doença bolha seca, causada pelo fungo Lecanicillium fungicola, provoca infecções graves que resultam em perdas significativas na produção de champignon. O controle se dá através de práticas sanitárias e do uso de fungicidas, porém no Brasil não há produtos registrados. Desta forma, este estudo objetivou avaliar o efeito de óleos essenciais extraídos de Melissa officinalis, Thymus vulgaris, Origanum vulgare, Eucalyptus globulus, Cinnamomum zeylanicum e Syzygium aromaticum sobre o desenvolvimento in vitro de isolados de L. fungicola e aplicação dos melhores óleos em teste in vivo. Além disso, a interação entre Agaricus bisporus e L. fungicola foi verificada por meio de microscopia eletrônica de varredura (MEV). Os óleos de canela e cravo a partir da concentração 0.4% e tomilho a 0.8% inibiram o crescimento micelial do patógeno. Já a germinação de conídios foi inibida pelo óleo de canela em todas as concentrações, bem como pelos óleos de cravo e tomilho, a 0.4% e 0.8%, respectivamente. No experimento in vivo, a aplicação dos óleos essenciais pós-infestação apresentou menor incidência da doença nos cogumelos produzidos. A MEV revelou que após 19 horas da inoculação de L. fungicola em A. bisporus, os esporos já estavam completamente germinados, o que indicava a ocorrência da infecção. Assim, os resultados deste trabalho sugerem que os óleos de canela, cravo e tomilho são alternativas potenciais para o controle da doença bolha seca.