Browsing by Author "Dias, Eduardo"
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- Disturbance, regeneration and the spatial pattern of tree species in Azorean mountain forestsPublication . Elias, Rui B.; Dias, Eduardo; Pereira, Fernando E. A.Disturbance related vegetation dynamics differs with Azorean mountain forest communities, where each tree species has its own regeneration strategy. Knowledge of the spatial distribution of tree species may help us to generate hypotheses on the relation between disturbance, regeneration and spatial organization and on the possible underlying ecological mechanisms. In view of this, we asked the following questions regarding the spatial pattern of tree species: What is the spatial distribution of saplings and adults? Are there any spatial associations or exclusions between saplings and adults of the same and different species? To what extent do the disturbance regimes and regeneration strategies of each species explain its spatial pattern? Six 225 m² (15 × 15 m) plots were placed in each of three different forest types in three Islands (Pico, Terceira and Flores). Patterns of tree individuals were analysed through Morisita’s index of dispersion (Iδ) and Iwao ω index. With the exception of Laurus azorica and Frangula azorica, saplings are in most cases aggregated. Erica azorica is the only species whose adults are aggregated at short distances. Spatial distribution is mostly random for the other species. At short distances, few strong associations or exclusions were detected. Pioneer species such as Juniperus brevifolia tend to be more aggregated due to their dependence on gaps to germinate and recruit new individuals. In fact, increasing disturbance and gap size enhances the regeneration of J. brevifolia. Primary species tend to be randomly distributed in part due to their strategy of forming seedling-sapling banks. Spatial pattern of tree species is largely explained by disturbance regimes and regeneration strategies of each species. However, factors such as habitat related patchiness, competition and dispersion limitation may also explain many of the observed patterns.
- First records of Tarentola mauritanica (Linnaeus, 1758) (Reptilia; Gekkonidae) in the AzoresPublication . Barreiros, João P.; Elias, Rui B.; Lourenço, Joana; Dias, Eduardo; Borges, Paulo A. V.The Moorish gecko Tarentola mauritanica (Linnaeus, 1758) is a widespread species native to the Mediterranean region from southern France to Greece and northern Africa (Loveridge 1947; Martínez-Rica 1997; Hódar 2002; Perera et al. 2008, 2010; Plezeguelos et al. 2008). It has recently been reported as living and breeding in California (Marhdt 1998) and also as an introduced species in Madeira (Báez & Biscoito 1993). Tarentola mauritanica is paraphyletic with respect to T. angustimentalis Steindachner, 1891, a Canary Islands endemic (Harris et al. 2004a). Here we report new occurrences of the Moorish gecko on Terceira Island, Azores archipelago, and 3 other occurrences on the islands of São Miguel and Faial. The possibility of an already established breeding population is discussed.
- The genera Melanoselinum Hoffm. and Angelica L. (Umbelliferae) in MacaronesiaPublication . Press, John R.; Dias, EduardoO género monotipico Melanosdinum Hoffm. da família Umbrelliferae é uma das endémicas mais numerosas da Macaronésia, sendo registada para os arquipélagos da Madeira e dos Açores. A única espécie é M. decipiens (Schrad. & J.C. Wendl.) Hoffm. As dúvidas levantadas por vários investigadores sobre a verdadeira identidade de M. decipiens fora da Madeira culminaram recentemente em as plantas açoreanas serem redesignadas como uma nova espécie de Angelica, A. lignescens Reduron & Danton. Apesar de uma descrição e ilustrações serem providenciadas pelos autores, outros dados para esta espécie são muito incompletos. Este artigo revê os gêneros Melanoselinum e Angelica na Macaronésia e fornece informações adicionais de A. lignescens, incluindo novos registos. M. decipiens é também descrita, lectotipificada e é fornecida a lista de todos os nomes correntemente publicados, usados e aceites de Melanoselinum.
- Genetic variability and differentiation among populations of the Azorean endemic gymnosperm Juniperus brevifolia: baseline information for a conservation and restoration perspectivePublication . Silva, Luís; Elias, Rui B.; Moura, Mónica; Meimberg, Harald; Dias, EduardoThe Azorean endemic gymnosperm Juniperus brevifolia (Seub.) Antoine is a top priority species for conservation in Macaronesia, based on its ecological significance in natural plant communities. To evaluate genetic variability and differentiation among J. brevifolia populations from the Azorean archipelago, we studied 15 ISSR and 15 RAPD markers in 178 individuals from 18 populations. The average number of polymorphic bands per population was 65 for both ISSR and RAPD. The majority of genetic variability was found within populations and among populations within islands, and this partitioning of variability was confirmed by AMOVA. The large majority of population pairwise F ST values were above 0.3 and below 0.6. The degree of population genetic differentiation in J. brevifolia was relatively high compared with other species, including Juniperus spp. The genetic differentiation among populations suggests that provenance should be considered when formulating augmentation or reintroduction strategies.
- Primary succession on lava domes on Terceira (Azores)Publication . Elias, Rui B.; Dias, EduardoVegetation attributes were consistent with the successional stage of each dome in the primary sere; however, the geomorphologic units did not follow the same pattern. The influence of the rates of plant colonization and soil formation are responsible for the decrease of the successional rates from footslopes, to summits, to slopes. The vegetation successionally changes from Juniperus scrub, to Juniperus wood and forest, and there is little species replacement since the similarity in species composition is high between the 3 domes.
- Projecto - IX Expedição Científica do Departamento de Biologia - Terceira 1994Publication . Tavares, João; Dias, Eduardo; Vieira, Virgílio; Furtado, DuarteA Ilha da Terceira foi este ano a escolhida para a realização desta expedição por motivos vários e com diferentes objectivos, entre as quais: a sua situação geográfica; o seu grande tamanho; a importância das Caldeiras existentes, com especial relevo para a Caldeira Guilherme Moniz e Santa Bárbara; os diversos ecossistemas que a compõem. Todos estes motivos permitirão um estudo exaustivo (pelas diferentes equipas de investigação) dos diversos ecossistemas que apresentam grande variabilidade, especialmente relacionados com as diferentes factores físicos e bióticos que os constituem. Para além dos dados científicos, que poderão ser objecto de publicação, será igualmente elaborada uma monografia sobre a ilha Terceira, com especial relevo para as zonas da Caldeira de Santa Bárbara, Guilherme Moniz e Ilhéu das Cabras, bem como para os diferentes ecossistemas que a compõem. Ficarão os responsáveis pela linha de investigação de Geografia Física e Humana encarregues de elaborar uma descrição geográfica da Ilha, aspectos sócio-económicos da utilização do solo e, se possível os mais importantes aspectos geomorfológicos e geológicos. Igualmente cabe aos restantes responsáveis pelas diferentes linhas de investigação, a elaboração dum relatório de actividades científicas que servirá de base à final publicação dum Relatório sobre a Ilha da Terceira. A edição deste trabalho interessa aos organismos regionais ligados ao Turismo, Educação e Cultura, bem como aos sectores Agrícola, Florestal e Pesqueiro, para além das Autarquias.
- The role of habitat features in a primary successionPublication . Elias, Rui B.; Dias, EduardoIn order to determine the role of habitat features in a primary succession on lava domes of Terceira Island (Azores) we addressed the following questions: (1) Is the rate of cover development related to environmental stress? (2) Do succession rates differ as a result of habitat differences? One transect, intercepting several habitats types (rocky hummocks, hollows and pits, small and large fissures), was established from the slope to the summit of a 247 yr old dome. Data on floristic composition, vegetation bioarea, structure, demography and soil nutrients were collected. Quantitative and qualitative similarities among habitats were also analyzed. Cover development and species accumulation are mainly dependent on habitat features. Habitat features play a critical role in determining the rate of succession by providing different environmental conditions that enable different rates of colonization and cover development. Since the slope’s surface is composed of hummocks, hollows and pits the low succession rates in these habitats are responsible for the lower rates of succession in this geomorphologic unit, whereas the presence of fissures in the dome’s summit accelerates its succession rate.