Poissons ratios for wood species for structural purposes

The broader knowledge about physical and mechanical properties of wood allows reliable timber structures design. Even little addressed in the literature, in several situations Poisson's ratios are required for the evaluation of stresses acting on structural elements. This study aimed to obtain values of Poisson's ratios (ν), plans Longitudinal-Radial (νLR) and Longitudinal-Tangential (νLT), for species Peroba Rosa (Aspidosperma polyneuron) and Jatobá (Hymenaea courbaril L.). For this purpose, forty samples Peroba Rosa and eight samples of Jatobá were prepared for testing in compression parallel to the grain, following the recommendations of ABNT NBR 7190 standard. The results of means confidence intervals, considered at the level of 5% significance, revealed that the Poisson's ratios νLR e νLT to Peroba Rosa are 0.27 and 0.42, respectively, and 0.25 and 0.43 to Jatobá.

Contribution of woody habitat islands to the conservation of birds and their potential ecosystem services in an extensive Colombian rangeland

The conservation of birds and their habitats is essential to maintain well-functioning ecosystems including human-dominated habitats. In simplified or homogenized landscapes, patches of natural and semi-natural habitat are essential for the survival of plant and animal populations. We compared species composition and diversity of trees and birds between gallery forests, tree islands and hedges in a Colombian savanna landscape to assess how fragmented woody plant communities affect forest bird communities and how differences in habitat characteristics influenced bird species traits and their potential ecosystem function. Bird and tree diversity was higher in forests than in tree islands and hedges. Soil depth influenced woody species distribution, and canopy cover and tree height determined bird species distribution, resulting in plant and bird communities that mainly differed between forest and non-forest habitat. Bird and tree species and traits widely co-varied. Bird species in tree islands and hedges were on average smaller, less specialized to habitat and more tolerant to disturbance than in forest, but dietary differences did not emerge. Despite being less complex and diverse than forests, hedges and tree islands significantly contribute to the conservation of forest biodiversity in the savanna matrix. Forest fragments remain essential for the conservation of forest specialists, but hedges and tree islands facilitate spillover of more tolerant forest birds and their ecological functions such as seed dispersal from forest to the savanna matrix.

Uso de indicadores bioquímicos na qualidade fisiológica de sementes florestais

The scientific research in seed technology is based on techniques that aim the reduction of costs and time, standardization, improvement and establishment of analytical methods while maintaining a high level of reliability of the results. This study sought to elucidate the reliability of electrical conductivity and pH of the exudate compared to the classic germination test, which was developed in two separate studies, however interrelated with each other, as to their final goals. The experimental material of this study consisted of seeds of the species Aspidosperma parvifolium (guatambu), Aspidosperma polyneuron (peroba-rosa), Cabralea canjerana (canjerana), Cariniana legalis (jequitibá), Gallesia integrifolia (pau-d'alho), Handroanthus chrysotrichus (ipê-amarelo), Lonchocarpus campestris (rabo-de-bugio) and Pterogyne nitens (amendoim-do-campo). The physiological quality of the studied seed species was evaluated through the electrical conductivity and pH test of the exudate by mass and individual methods being compared and correlated with the results obtained in the germination test. In addition to the tested methods, imbibition periods of the seeds were evaluated for conductivity and pH, which corresponded to 2, 4, 6, 8, 24 and 48 hours. The electrical conductivity test was efficient in both of the used methods to evaluate the physiological quality of the studied seed species when compared to the standard germination test. The pH test of the exudate applied by the individual method was more efficient and thorough to evaluate the physiological quality of the studied seed species, than the mass method. For the species Gallesia integrifolia, Cariniana legalis and Lonchocarpus campestris the pH tests of the exudate tests were not efficient due to poor or absent correlation between germination and pH.

Produção de serapilheira de árvores e arbustos de sistemas agrossilvipastoris da caatinga em Sobral, CE.

O conhecimento da deposição de serapilheira e da ciclagem de nutrientes de espécies nativas da Caatinga é de grande importância, principalmente, para a verificação do aporte de nutrientes em sistemas agrossilvipastoris em região semiárida. Com isso objetivou-se avaliar a produção total de serapilheira de árvores e arbustos de um Sistema Agrossilvipastoril em área de Caatinga. O ensaio foi desenvolvido no Sistema Agrossilvipastoril da Embrapa Caprinos e Ovinos, em Sobral ? CE. As espécies avaliadas foram: catingueira (Poincianela pyramidalis), jucá (Libidibia ferrea), jurema-preta (Mimosa tenuiflora), marmeleiro (Croton sonderianus), mofumbo (Combretum leprosum), pau-branco (Auxemma oncocalyx), pereiro (Aspidosperma pirifolium) e sabiá (Mimosa caesalpiniaefolia).

Restauração de florestas exploradas seletivamente no Acre.

Por meio de técnicas de restauração, florestas exauridas podem ser conduzidas de maneira a minimizar os efeitos da exploração seletiva que as modificaram. O plantio de mudas é um método rápido e eficaz de restauração de florestas. Este trabalho objetiva descrever os resultados de plantios de enriquecimento de florestas de produção nos municípios de Xapuri, Brasiléia e Rio Branco, no estado do Acre. Foram utilizadas dez espécies florestais madeireiras comerciais: amarelão (Aspidosperma vargasii A. DC.), angelim (Ormosia arborea (Vell.) Harms), cedro (Cedrela odorata L.), cerejeira (Amburana acreana (Ducke) A. C. Sm.), freijó (Cordia alliodora (Ruiz & Pav.) Oken), ipê (Tabebuia serratifolia (Vahl) G. Nicholson), itaúba (Mezilaurus itauba (Meisn.) Taub. ex Mez), jatobá (Hymenaea courbaril L.), mogno (Swietenia macrophylla King) e timbaúba (Enterolobium maximum Ducke). Os plantios foram entre outubro/2011 a março/2012, totalizando 1273 mudas. Os tratamentos silviculturais de condução e o monitoramento foram nos anos de 2012, 2013, 2014 e 2015. Após 48 meses ao plantio, a taxa média de sobrevivência foi de 42,3%, altura total média de 1,52 m e diâmetro médio de 1,88 cm. As espécies com os melhores desempenhos com relação a crescimento e sobrevivência foram cerejeira, cedro, freijó, jatobá, mogno e timbaúba.