Above ground biomass functions with vegetation indices for multiple use systems of two evergreen oaks

Remote sensing is a promising approach for above ground biomass estimation, as forest parameters can be obtained indirectly. The analysis in space and time is quite straight forward due to the flexibility of the method to determine forest crown parameters with remote sensing. It can be used to evaluate and monitoring for example the development of a forest area in time and the impact of disturbances, such as silvicultural practices or deforestation. The vegetation indices, which condense data in a quantitative numeric manner, have been used to estimate several forest parameters, such as the volume, basal area and above ground biomass. The objective of this study was the development of allometric functions to estimate above ground biomass using vegetation indices as independent variables. The vegetation indices used were the Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Simple Ratio (SR) and Soil-Adjusted Vegetation Index (SAVI). QuickBird satellite data, with 0.70 m of spatial resolution, was orthorectified, geometrically and atmospheric corrected, and the digital number were converted to top of atmosphere reflectance (ToA). Forest inventory data and published allometric functions at tree level were used to estimate above ground biomass per plot. Linear functions were fitted for the monospecies and multispecies stands of two evergreen oaks (Quercus suber and Quercus rotundifolia) in multiple use systems, montados. The allometric above ground biomass functions were fitted considering the mean and the median of each vegetation index per grid as independent variable. Species composition as a dummy variable was also considered as an independent variable. The linear functions with better performance are those with mean NDVI or mean SR as independent variable. Noteworthy is that the two better functions for monospecies cork oak stands have median NDVI or median SR as independent variable. When species composition dummy variables are included in the function (with stepwise regression) the best model has median NDVI as independent variable. The vegetation indices with the worse model performance were EVI and SAVI.

Concepções dos alunos sobre a avaliação das aprendizagens na disciplina de matemática em anos terminais dos 1º e 2º ciclos do ensino básico

A presente investigação tem como objectivo o estudo das concepções dos alunos sobre a avaliação das aprendizagens na disciplina de Matemática em anos terminais dos 1º e 2° ciclos do Ensino Básico. Em particular, procurou-se estudar e comparar as concepções que alunos desses anos tinham sobre a avaliação e as práticas avaliativas dos seus professores, e compreender se existiam algumas relações de dependência entre essas concepções e a perspectiva face à Matemática e o desempenho escolar desses alunos. O enquadramento teórico está organizado em dois capítulos. O primeiro relacionado com a avaliação e o segundo referente às concepções. Este estudo segue uma metodologia de natureza interpretativa. A recolha de dados foi feita através da aplicação de um questionário a quatro turmas, uma do 4o e outra do 6° ano de escolaridade de dois agrupamentos distintos, um de Elvas e outro de Portalegre, e de entrevista semi-estruturada a dois alunos por turma. A análise de dados foi organizada em tomo de duas categorias: (i) perspectivas face à Matemática e (ii) perspectiva face à avaliação das aprendizagens. Os resultados do estudo indicam que as concepções sobre a avaliação das aprendizagens em Matemática dos alunos participantes incidem, preferencialmente, sobre sentimentos, consequências, funções e instrumentos de avaliação. Verifica-se uma tendência para a existência de relações de dependência entre a imagem negativa da Matemática escolar e a concepção de avaliação associada aos sentimentos. Alunos com classificações negativas a Matemática associa, igualmente, a avaliação a sentimentos. Já os alunos que têm uma imagem positiva da Matemática, assim com os que têm classificações mais elevadas, tendem a associar a avaliação às suas consequências. No que diz respeito às práticas avaliativas que lhes têm sido proporcionadas, os alunos do 1º e do 2°ciclos apresentam concepções quase semelhantes, reconhecendo as fichas de avaliação como os instrumentos com mais peso para o professor na atribuição de notas no final do período. Os alunos do 1º ciclo são os que mais revelam concordar que o professor está atento às suas dificuldades. Porém, quer os alunos do 1 o e do 2°ciclos não reconhecem poder combinar com o professor a forma como são avaliados. ABSTRACT; The main purpose of the present work is to study the students' beliefs on assessment learning related to the Mathematics subject in ending years of 1st and 2nd key stage of elementary school. ln particular, the research was aimed to study and compare the students’ beliefs that pupils of those particular years had on assessment and the assessment practices of their teachers and also if there were any kind of dependence relationships between those beliefs and the perspective towards Mathematics and those students' school performance. The theoretical framework is organized in two chapters. The first related with the assessment and the second regarding the beliefs. This study follows a methodology of interpretative nature. The data gathering was done through the application of a questionnaire to four classes, one of the 4th and another of the 6th year of two different school groups, one belonging to Elva’s and another one to Portalegre and also through a semi-structured interview done to two students per group. The data analysis was organized around two categories: (i) perspectives towards Mathematics and (ii) perspective towards assessment learning. The results of the study show that the beliefs of those students on assessment learning on Mathematics are preferably based on feelings, consequences, functions and assessment instruments. ln general terms, there seems to be dependence relationships between the Mathematics negative image and the assessment conception associated to feelings. Students with negative marks at Mathematics also associate assessment to feelings. Those who have a positive Mathematics image, as well as those with higher marks at the subject, seem to associate assessment to its consequences. Concerning the assessment practices that have been provided to students from 1 51 and 2nd key stage of elementary school, these same pupils show very similar beliefs, pointing the summative tests as having higher importance when the assessment term comes. The students of the 1st key stage of elementary school are those who most agree that the teacher is attentive to their difficulties. Even so, both groups of students say that they cannot negotiate with their teacher the way they are supposed to be assessed.

Above ground biomass estimation in Mediterranean multiple use systems with high spatial resolution satellite images

Forest biomass has been having an increasing importance in the world economy and in the evaluation of the forests development and monitoring. It was identified as a global strategic reserve, due to its applications in bioenergy, bioproduct development and issues related to reducing greenhouse gas emissions. The estimation of above ground biomass is frequently done with allometric functions per species with plot inventory data. An adequate sampling design and intensity for an error threshold is required. The estimation per unit area is done using an extrapolation method. This procedure is labour demanding and costly. The mail goal of this study is the development of allometric functions for the estimation of above ground biomass with ground cover as independent variable, for forest areas of holm aok (Quercus rotundifolia), cork oak (Quercus suber) and umbrella pine (Pinus pinea) in multiple use systems. Ground cover per species was derived from crown horizontal projection obtained by processing high resolution satellite images, orthorectified, geometrically and atmospheric corrected, with multi-resolution segmentation method and object oriented classification. Forest inventory data were used to estimate plot above ground biomass with published allometric functions at tree level. The developed functions were fitted for monospecies stands and for multispecies stands of Quercus rotundifolia and Quercus suber, and Quercus suber and Pinus pinea. The stand composition was considered adding dummy variables to distinguish monospecies from multispecies stands. The models showed a good performance. Noteworthy is that the dummy variables, reflecting the differences between species, originated improvements in the models. Significant differences were found for above ground biomass estimation with the functions with and without the dummy variables. An error threshold of 10% corresponds to stand areas of about 40 ha. This method enables the overall area evaluation, not requiring extrapolation procedures, for the three species, which occur frequently in multispecies stands.

Estudo preliminar sobre a ação antimicrobiana de óleos essenciais sobre agentes etiológicos de mastite em ovelhas

The control of mastitis is currently reliant on antibiotic utilization. Nevertheless antibiotics overuse and use without criteria leads to the development of resistant strains with negative consequences both in animal and public health. Essential oils (EOs) are classified as GRAS (generally recognized as safe), are provided with antimicrobial properties and no resistance has been reported after use. The aim of this study was to evaluate the antimicrobial activity of EOs of aromatic herbs, growing wild in Alentejo region and widely used in Mediterranean food, against microorganisms isolated from ovine mastitic milk.