Emergetic evaluation of cattle rearing in a montado farm

O Montado, em Portugal, é um complexo sistema silvopastoril de uso da terra, tipicamente Mediterrânico, com diversos estratos de vegetação, incluindo sobreiro e azinheira em várias densidades, onde é frequente a criação de gado. Esta actividade pecuária beneficia das pastagens no sob-coberto, de algumas espécies arbustivas e também das bolotas que caem do coberto arbóreo, contribuindo para evitar a invasão da pastagem por matos. No entanto, dependendo da sua gestão, este gado pode comprometer a regeneração do sistema. Nos últimos 20 anos, os subsídios no âmbito da Política Agrícola Comum da União Europeia têm promovido a criação de gado bovino em detrimento de outras espécies e raças mais leves, bem como a intensificação desta produção. Esta intensificação pode impossibilitar a regeneração natural das árvores ameaçando o equilíbrio do Montado. Por esta razão é necessária uma avaliação focada na criação de gado bovino e nos seus impactos sobre o sistema. O objectivo deste estudo foi obter uma melhor compreensão do funcionamento de uma exploração silvopastoril num sistema de Montado, através da aplicação do Método de Avaliação Emergética e do cálculo de índices emergéticos. Pretende-se assim compreender a melhor forma de o gerir, bem como conceber estratégias que maximizem o fluxo de emergia na exploração. Uma comparação deste método com a avaliação económica permitiu perceber em que aspectos esta pode ser complementada pelo método da avaliação emergética. O método da avaliação emergética permite a avaliação de sistemas multifuncionais complexos à escala de uma exploração individual, fornecendo informação extra em relação à avaliação económica como a renovabilidade dos inputs do sistema, ou a quantidade de fluxos livres da natureza que é valorada por preços de mercado. Este método permite a integração das emternalidades e das externalidades à contabilização económica, transformando uma avaliação tendencialmente separada do seu sistema mais vasto, numa avaliação de um sistema em conexão com aqueles mais vastos nos quais se integra; Abstract: The Montado, in Portugal, is a complex silvo-pastoral system of land use, typically Mediterranean, with different strata of vegetation, including cork and holm oaks in various densities, and where cattle rearing is common. This stockfarm benefits from the herbaceous layer under the trees, as well as from some species in the shrub layer, and also from the acorns faling down from the tree cover, while contributing to prevent the invasion of pastures by shrubs. Nevertheless, depending on its management, livestock can affect the system regeneration. Over the past 20 years, subsidies of the European Union's common agricultural policy have promoted the cattle rearing at expense of other lighter species and breeds, as well as its intensification. This intensification may impair the natural regeneration of trees threatening the balance of the Montado. Therefore an assessment focused on cattle and their impact on the system is required. The purpose of this study was to obtain a better understanding of the functioning of a silvo-pastoral farm in a Montado system, by applying the emergy evaluation method and through the calculation of emergy indices. It is intended to understand the best way to manage and design strategies that maximize the emergy flow on the farm. A comparison of this method with the economic evaluation allowed to realize in what aspects it can be complemented by the emergy evaluation method. The emergy evaluation method alows the assessment of complex multi-functional systems at the scale of an individual farm, providing extra information in relation to economic avaluation as the renewability of the inputs to a system and the amount of free flows of nature that is valued by market prices. This method allows the integration of the emternalities and the externalities to the economic accounting, transforming an evaluation tended separated from its wider system, in an evaluation of a system in connection with the larger ones on which it is incorporated.

Generalities of vertebrate responses to landscape composition and configuration gradients in a highly heterogeneous Mediterranean region

Aim To examine the distributional patterns of vertebrates (including birds, bats, carnivores and lagomorphs) along landscape composition and configuration gradients to better understand the effects of landscape modification on occurrence patterns at both species and community level. Location The region of Alentejo, a forest-dominated area of southern Portugal. Methods The study area was framed using 1647 hexagonal plots, each of 259 ha in size. Composition and configuration gradients were obtained for each plot by integrating the proportions of the main land cover types and their configuration patterns using multivariate analyses. Species-specific vertebrate responses were investigated using data from 75 plots in which carnivores, bats and lagomorphs were sampled, and from 135 plots in the case of birds. Community- level responses were investigated through changes in species richness and beta-diversity in 57 plots where all vertebrate groups were simultaneously sampled. At the species-level, an information-theoretic approach was used to determine the effects of landscape gradients on species’ responses. At the community level, Mantel tests were used to determine between-plot differences in species composition using the Sørensen dissimilarity index. Results We found that the occurrence patterns of most vertebrate species were best predicted by composition-related gradients, although configuration gradients were also frequently included in species-specific occurrence models. We also found a weak correlation between species richness and most landscape gradients suggesting a turnover in the identity of species, something that was corroborated by the stronger correlation between environmental gradients and beta-diversity measures. The amount of forest cover and landscape complexity (estimated as the heterogeneity in the size and number of land cover types) were the main composition and configuration gradients determining vertebrate responses at both species and community level. Main conclusions Our work contributes to a more refined understanding of the mechanisms underlying species distributional patterns in real-world human-modified landscapes. By uncovering generalities of species with multiple ecological requirements and by describing the entire landscape mosaic through landscape gradients, we also suggest that our work greatly helps to fill the gap between existing conceptual landscape models aimed to understand species distributional patterns in human-modified landscapes.

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.