ASPECTOS DA VARIAÇÃO AMBIENTAL EM UMA FLORESTA DE GALERIA EM ITUTINGA, MG, BRASIL

Foi caracterizada a heterogeneidade ambiental em uma área de floresta de galeria (7,55 ha), em Itutinga, MG, Brasil, pelas variações das propriedades químicas e físicas do solo, da topografia e da abertura de dossel. As propriedades do solo e a topografia foram estudadas em 28 parcelas de 10 x 30 m utilizadas em um levantamento da comunidade arbóreo-arbustiva da área. Para a abertura do dossel utilizaram-se duas transecções de 50 m de largura, compostas por parcelas contíguas de 10 x 10 m, cruzando a floresta de lado a lado, perpendicularmente ao curso d’água. Fotos hemisféricas foram tomadas sobre estacas alternadas das extremidades das parcelas. Os dados de solo e topografia foram analisados por meio de uma PCA (Análise dos Componentes Principais) e a abertura do dossel mediante gráficos de tendência e regressão linear. A variação mais importante em termos de solos e abertura do dossel se deu no sentido do distanciamento da borda da floresta e aproximação do curso d’água. Nesse sentido, a abertura do dossel diminuiu (b = -0,096; R2 = 0,34) e a umidade e acidez do solo aumentaram (Eixo 1 do PCA, autovalor = 9,713). Os maiores valores da abertura do dossel próximo à borda foram explicados pela entrada de luz lateral através da borda da floresta com o campo limpo circundante

Characterization of a semideciduous forest in varginha, MG. and comparison with remaining forest fragments in the region

Foi realizado o levantamento florístico e fitossociológico na porção mais extensa de mata no Parque Florestal Municipal São Francisco de Assis, na cidade de Varginha, sul de Minas Gerais. A área tem cerca de 10 ha e é cortada por um pequeno córrego. Foram lançadas 25 parcelas de 20m x 20m e medidos e cadastrados todos os indivíduos arbóreos com DAP > 5cm. Foram encontrados 1568 indivíduos que, juntos, somaram área basal de 23,65 m2, sendo registrados 102 espécies, 72 gêneros e 42 famílias no levantamento fitossociológico e 111 espécies, 77 gêneros e 43 famílias no levantamento florístico. As famílias com maior número de espécies foram Myrtaceae, Fabaceae e Melastomataceae. As espécies de maior valor de importância foram Casearia arborea, Copaifera langsdorffii, Tachigali rugosa e Myrcia splendens. Os resultados encontrados são os esperados para as Florestas Estacionais Semideciduais da região.A floristic and phytossociological survey was made at the biggest area of continue forest at Parque Florestal Municipal Sao Francisco de Assis, in Varginha county, south of Minas Gerais state. The area has 10 ha and possesses a water stream. It was sampled 25 plots of 20m x 20m and recorded all the individuals with diameter at breast height (DBH) equal to or larger than 5 cm. The phytossociological survey recorded 1568 individuals, and basal area of 23.65 m(2.)ha(-1) distributed in 103 species, 72 genera and 42 families. The floristic survey recorded 111 species, 77 genera and 43 families. The families with bigger number of species were: Myrtaceae, Fabaceae and Melastomataceae and the most important species were Casearia arborea, Copaifera langsdorffii, Tachigali rugosa and Myrcia splendens. The obtained results are in accordance wih the expected ones for the semideciduous seasonal forests of the region

Design and Synthesis of Visible-Light-Responsive Azobenzene Building Blocks for Chemical Biology

Tetra-ortho-fluoro-azobenzenes are a class of photoswitches useful for the construction of visible-light-controlled molecular systems. They can be used to achieve spatio-temporal control over the properties of a chosen bioactive molecule. However, the introduction of different substituents to the tetra-fluoro-azobenzene core can significantly affect the photochemical properties of the switch and compromise biocompatibility. Herein, we explored the effect of useful substituents, such as functionalization points, attachment handles, and water-solubilizing groups, on the photochemical properties of this photochromic system. In general, all the tested fluorinated azobenzenes exhibited favorable photochemical properties, such as high photostationary state distribution and long half-lives, both in organic solvents and in water. One of the azobenzene building blocks was functionalized with a trehalose group to enable the uptake of the photoswitch into mycobacteria. Following metabolic uptake and incorporation of the trehalose-based azobenzene in the mycobacterial cell wall, we demonstrated photoswitching of the azobenzene in the isolated total lipid extract

Phylogenetic regionalization of tree assemblages reveals novel patterns of evolutionary affinities in the Atlantic Forest

peer reviewedAim: We used a phylogenetic approach to group assemblages of woody plant into major vegetation units in the Atlantic Forest, thus for the first time incorporating information on species evolutionary relationships into a bioregionalization of this critical hotspot. A phylogenetic regionalization will provide a spatially explicit framework for answering many basic and applied questions in biogeography, ecology and conservation. Location: Atlantic Forest. Taxon: Angiosperms. Methods: Our data set comprises 614 genera and 116 families, spread over 1,755 assemblages. To place assemblages in a multivariate evolutionary composition space, we used a phylogenetically informed ordination analysis, and to determine what the main phylogenetic groups of assemblages were, we used K-means clustering based on phylogenetic dissimilarity of assemblages. To quantify how well environmental variables distinguish the phylogenetic groups found, we implemented classification tree approaches. Then, to explore the evolutionary turnover between the phylogenetic groups, we calculated phylogenetic beta diversity. Finally, we determined the lineages that are most strongly associated with individual phylogenetic groups using an indicator analysis for lineages. Results: Our analyses suggest that there are seven principal groups, in terms of evolutionary lineage composition, in the Atlantic Forest. The greatest turnover of phylogenetic lineage composition separates tropical evergreen rain forest and semideciduous assemblages from subtropical and highland assemblages. The mixed subtropical forest showed the lowest phylogenetic compositional similarity values with other groups. Tropical rain forest had the highest number of significant indicator lineages, and the highest values of the indicator statistic for lineages. Main conclusions: We found that the most pronounced evolutionary division separates southern and highland tree assemblages from those occurring under more tropical climates and at lower elevations. Our phylogenetic analyses point to an environmentally driven compositional division, likely based on the regular occurrence of freezing versus non-freezing temperatures. Precipitation and edaphic regimes that assemblages experience had less definitive effects on their evolutionary lineage composition

Tree population dynamics in alluvial forest fragments in south of Minas Gerais, Brazil

The present study aimed to evaluate the tree population dynamics in forest fragments, in the municipality of São Sebastião da Bela Vista, MG. For this sake, all living trees with diameter at breast height (DBH) higher than 5 cm, present in the sampled units, were measured (DBH and height) and identified in 2005 and monitored in 2007 and 2009 (remeasured and mortality evaluation), when all individuals reaching the minimum diameter of inclusion, on the occasion of a possible recruitment, were recruited. The annual dynamics rates (mortality, recruitment, turnover and net change) were calculated for all populations. Dynamics instability was observed, indicated by the steady reduction of abundance and the higher number of species with negative balance in abundance (period 2005 a 2007 = 13 e 2007 a 2009 = 17) than positive balance (2005 a 2007 = 9 e 2007 a 2009 = 14). The richness changes were insignificant, with the gain of two species and loss of just one. The present study demonstrated that, despite the observation of no qualitative (floristic) changes, the evaluated area showed a dynamics with structural instability, with higher mortality than recruitment.O presente estudo objetivou avaliar a dinâmica de populações arbóreas em fragmentos florestais em São Sebastião da Bela Vista, MG. Para isso, todos os indivíduos arbóreos com diâmetro na altura do peito (DAP) maior do que 5 cm, presentes nas unidades amostrais, foram medidos (DAP e altura) e identificados no ano de 2005 e monitorados nos anos 2007 e 2009 (remedição e verificação de mortalidade), quando também foram medidos os indivíduos que alcançaram o diâmetro mínimo de inclusão por ocasião de um eventual recrutamento. Foram calculadas as taxas de dinâmica anual (mortalidade, recrutamento, rotatividade e mudanças líquidas) para todas as populações. Foi observada instabilidade da dinâmica, indicada pela redução constante da abundância e pelo maior número de espécies com balanço negativo de número de indivíduos (período 2005 a 2007 = 13 e 2007 a 2009 = 17) do que balanço positivo (2005 a 2007 = 9 e 2007 a 2009 = 14). As mudanças de riqueza foram insignificantes, com o ganho de duas espécies e o desaparecimento de uma. O estudo demonstrou que, apesar de não apresentar mudanças qualitativas (composição florística), a área demonstrou instabilidade estrutural, com mais populações com maior taxa de mortalidade que de recrutamento

Dynamics of the shrub-tree component of an alluvial gallery forest on the Poços de Caldas Plateau, MG State, Brazil

A dinâmica do componente arbustivo-arbóreo foi investigada em uma floresta de galeria aluvial em Poços de Caldas, Minas Gerais, entre 1998 e 2005. Os objetivos principais foram: investigar se as taxas de dinâmica das florestas de galeria aluviais são inferiores a outras formações florestais ripárias tropicais e, se as inundações periódicas geram variação espacial na dinâmica no sentido Rio-Borda. A amostragem foi composta de 101 parcelas de 10 × 10 m, distribuídas em 5 blocos ao longo de, aproximadamente, 8 km da floresta do Rio das Antas. Cada bloco foi dividido em 3 setores (Rio, Interior e Borda). Comparativamente a outras florestas tropicais ripárias, a floresta em estudo apresentou taxas de dinâmica mais lentas. A Borda foi mais dinâmica que os outros setores, provavelmente devido à maior incidência luminosa, propiciando ambiente adequado às espécies de ciclo de vida curto.The dynamics of the shrub-tree component was investigated in an alluvial gallery forest in Poços de Caldas, Minas Gerais, from 1998 to 2005. The main objective of this study was to verify if the rates of the dynamics of the alluvial gallery forests are less than other tropical riparian forest formations. Seasonal flooding was also studied to see if it generates a spatial variation in the dynamics of going from the stream side towards the forest border. The sample consisted of 101, 10×10-meter plots that were distributed in five blocks extending approximately 8 km along the Antas River's forest. Each block was divided into three sectors (stream side, forest interior, and forest edge). Compared with other tropical forests, especially the riparian ones, this forest showed lower rates in terms of structural alterations. The forest edge is more dynamic, mainly due to the greater amount of sunlight, which supplies an adequate environment for species with a short life cycle

Caracterização ecológica de espécies arbóreas ocorrentes em ambientes de mata ciliar, como subsídio à recomposição de áreas alteradas nas cabeceiras do Rio Grande, Minas Gerais, Brasil.

The objective of this study was to verify the differences in the composition of the flora and of guilds of arbustive-arboreal communities of three areas of ciliary forest, in different forest succession stages. Fourty-six plots of 400 m2 were allocated and all existent arboreal individuals inside the portions with diameter breast height (DBH) greater than or equal to 5cm were sampled. A total of 282 species, distributed in 140 genera and 61 families were identified. With regard to dispersal guilds, it was found that on average, the spread of sources of propagules of 72% of the species and 59% of the individuals was zoochorous, while 19% and 23%, respectively, was wind anemocoric, and 6% and 13%, respectively, was autochoric. The proportions of individuals per species and ecological group were, respectively, pioneers: 14.5% and 18%; climax demanding of light: 49.5% and 62.5%, and shade-tolerant: 36.5% and 21.5%. It was also verified that there was a significant increase in the importance of animal dispersed species and shade tolerant species with the maturity of forests, while the number of species that required light abiotically dispersed decreased significantly with the advancement of maturity.Este estudo teve como objetivo verificar as diferenças na composição da flora e das guildas das comunidades arbustivo-arbóreas em três áreas de mata ciliar em diferentes estágios de sucessão florestal. Foram alocadas 46 parcelas de 400 m2 e todos os indivíduos arbóreos existentes no seu interior, com diâmetro à altura do peito (DAP) = 5 cm, foram amostrados. Foram identificadas 282 espécies distribuídas em 140 gêneros e 61 famílias. No que se refere às guildas de dispersão, constatou-se que, em média, 72% das espécies e 59% dos indivíduos têm suas fontes de propágulos disseminadas por animais (zoocórica), 19% e 23% pelo vento (anemocórica) e 6% e 13% por meio barocoria ou balística (autocórica). As proporções de espécies e indivíduos por grupo ecológico foram, respectivamente, pioneiras: 14,5% e 18%; clímax exigente de luz: 49,5% e 62,5% e, clímax tolerante à sombra: 36,5% e 21,5%.Verificou-se, ainda, que houve um aumento significativo da importância das espécies zoocóricas e tolerantes à sombra com a maturidade das florestas, enquanto o número de espécies que necessitam de luz com dispersão abiótica decresceu significativamente com o avanço dessa maturidade

Ecological Characterization Of Arboreal Species Ocurring In Ciliary Forest Environment, As Basis For The Recovery Of Areas Altered In The Headboards Of Rio Grande, Minas Gerais, Brazil1

Este estudo teve como objetivo verificar as diferen\ue7as na composi\ue7\ue3o da flora e das guildas das comunidades arbustivo-arb\uf3reas em tr\ueas \ue1reas de mata ciliar em diferentes est\ue1gios de sucess\ue3o florestal. Foram alocadas 46 parcelas de 400 m2 e todos os indiv\uedduos arb\uf3reos existentes no seu interior, com di\ue2metro \ue0 altura do peito (DAP) = 5 cm, foram amostrados. Foram identificadas 282 esp\ue9cies distribu\ueddas em 140 g\ueaneros e 61 fam\uedlias. No que se refere \ue0s guildas de dispers\ue3o, constatou-se que, em m\ue9dia, 72% das esp\ue9cies e 59% dos indiv\uedduos t\ueam suas fontes de prop\ue1gulos disseminadas por animais (zooc\uf3rica), 19% e 23% pelo vento (anemoc\uf3rica) e 6% e 13% por meio barocoria ou bal\uedstica (autoc\uf3rica). As propor\ue7\uf5es de esp\ue9cies e indiv\uedduos por grupo ecol\uf3gico foram, respectivamente, pioneiras: 14,5% e 18%; cl\uedmax exigente de luz: 49,5% e 62,5% e, cl\uedmax tolerante \ue0 sombra: 36,5% e 21,5%.Verificou-se, ainda, que houve um aumento significativo da import\ue2ncia das esp\ue9cies zooc\uf3ricas e tolerantes \ue0 sombra com a maturidade das florestas, enquanto o n\ufamero de esp\ue9cies que necessitam de luz com dispers\ue3o abi\uf3tica decresceu significativamente com o avan\ue7o dessa maturidade.The objective of this study was to verify the differences in the composition of the flora and of guilds of arbustivearboreal communities of three areas of ciliary forest, in different forest succession stages. Fourty-six plots of 400 m2 were allocated and all existent arboreal individuals inside the portions with diameter breast height (DBH) greater than or equal to 5cm were sampled. A total of 282 species, distributed in 140 genera and 61 families were identified. With regard to dispersal guilds, it was found that on average, the spread of sources of propagules of 72% of the species and 59% of the individuals was zoochorous, while 19% and 23%, respectively, was wind anemocoric, and 6% and 13%, respectively, was autochoric. The proportions of individuals per species and ecological group were, respectively, pioneers: 14.5% and 18%; climax demanding of light: 49.5% and 62.5%, and shade-tolerant: 36.5% and 21.5%. It was also verified that there was a significant increase in the importance of animal dispersed species and shade tolerant species with the maturity of forests, while the number of species that required light abiotically dispersed decreased significantly with the advancement of maturity