Avaliação da influência altitudinal nas comunidades de aves dos montados de sobro em Portugal: aspectos biogeográficos e ecológicos

Os montados são sistemas agro-silvo-pastoris de origem antropogénica dominados pelo sobreiro (Quercus suber) e/ou azinheira (Q. rotundifolia). São considerados sistemas de Elevado Valor Natural (High Nature Value, HNV) e estão incluídos no Anexo I da Directiva Habitats da União Europeia (92/43/CEE). No entanto, alguns montados estão ameaçados devido ao abandono da terra, sobre-pastoreio e agentes patogénicos. Vários estudos têm demonstrado que a distribuição das aves nos montados está relacionada com a gestão das florestas e áreas agrícolas. Estes habitats são conhecidos por terem uma elevada riqueza de aves florestais e também espécies de áreas abertas. Com este estudo podemos concluir que a diversidade de espécies lenhosas beneficia o aparecimento de espécies de aves com diferentes requisitos de habitat. Demonstrou-se também que não existe uma relação significativa entre a distribuição da comunidade de aves e a altitude na nossa área de estudo. E por último, as espécies especialistas do sobreiro podem ser consideradas bioindicadores de áreas bem preservadas de montado uma vez que existem em maiores densidades quando o insecto C. florentinus aparece em menor frequência; ABSTRACT: The montados are agro-silvo-pastoral systems of anthropogenic origin dominated by cork oak (Quercus suber) and/or holm oak (Q. rotundifolia). They are considered High Nature Value Farmlands (HNVF) and are included in Annex I of the European Union Habitats Directive (92/43/CEE). Nevertheless, some of these habitats are threatened by land abandonment, overgrazing and pathogenic agents. Several studies have shown that bird distribution in montados is related to forest and farmland management. These habitats are known to have high richness in breeding birds as they encompass not only forest but also farmland species. However, the effects of landscape composition on avian communities in forest dominated landscapes are not well studied. With this study we can conclude that the diversity of woody species benefits the appearance of bird species with different habitat requirements. It was also demonstrated that there is no significant relation between the distribution of bird communities and altitude in our study area. Finally, cork oak specialists can be considered as bioindicators of well-preserved montados since they exist at greater densities when the insect C. florentinus appears less frequently

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved