31 research outputs found

    Sintra vegetation and landscape

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    The field trip to Sintra region, as part of the 48th IAVS Symposium, aims to illustrate well-preserved and representative plant communities of Sintra municipality. It consists of two short field stops and a 3 km wal

    Influence of soil and organic residue management on biomass and biodiversity of understory vegetation in a Eucalyptus globulus Labill. plantation

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    The objective of this study was to assess the effect of different options of soil preparation and management of harvesting debris on biodiversity and biomass of understory vegetation in plantations of Eucalyptus globulus of Central Portugal. The experiment consisted of six treatments in a replanted area and four treatments in a coppice area with five replicates, following a randomised block design. Surveys of vegetation were performed for 6 years. The proportion of soil cover by plant specieswas estimated and the Shannon–Wiener diversity and equitability indexes determined for each treatment and year. After the 2nd year, the understory vegetation was randomly sampled for above-ground biomass determination.Within the planted area, the removal of slash without soil preparation induced the highest number of species during the experimental period. A similar trend was observed in the coppice area, but less regularly. Significant differences in the proportion of soil cover only occurred within the planted area in the first year, when slash removal without soil preparation induced the highest understory cover. Species diversity was not clearly affected by treatments: significant differences only occurred occasionally and were apparently related to differences in the number of species. Therefore, differences in the equitability index between treatments never were significant. Removal of slash without soil disturbance and broadcast of slash over the soil usually shared the highest biodiversity. Differences between treatments in the amount of understory biomass were never statistically significant during the experimental period. Tendency for a negative influence of soil mobilisation on the amount of understory biomass was observed within the planted area, as well as a similar effect of the treatments consisting of broadcast of slash over the soil surface in the coppice area. In parallel to tree development and canopy closure biomass of that vegetation along the study period was reduced, especially in the planted area

    Effects of harrowing and fertilisation on understory vegetation and timber production of Eucalyptus globulus Labill. plantation in central Portugal

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    Harrowing and fertilisation are common practices at middle rotation in Eucalyptus globulus Labill. plantations in Central Portugal. In order to clarify the effects of such practices on understory vegetation and timber production, a field trial was installed in a 5-year-old first rotation eucalyptus plantation, in a region with mixed oceanic and Mediterranean climatic influences. Four treatments that involved harrowing (H), fertilisation (F), harrowing and fertilisation (HF), and control (C) were tested in the study. The treatments were replicated four times and arranged in a simple completely randomised design. Vegetation surveys were performed by the quadrat method in the 3 years following treatments and by the line interception method in the 7th and 8th years. Samples of understory biomass were collected, oven dried and weighed. In treatments with harrowing, the understory vegetation consistently had lower number of species, less plant cover, species diversity, and biomass than the other treatments. The mean total number of species only once reached 10 in H or HF plots, and was always greater than 12 in C and F plots in the first 3 years, but decreased in the 7th and 8th years. In the first 3 years, the understory biomass averaged 30–60 g m 2 in the F and C plots, and never exceeded 13 g m 2 in treatments with harrowing, which corresponded with the proportion of soil coverage by understory vegetation (4–12% in H and HF, and 38–62% in F and C plots). In the 7th and 8th years, differences in the understory biomass were less important, but the control plots consistently had the largest understory biomass. The influence of treatments in timber production was not statistically significant at the end of rotation

    Species richness and biomass of understory vegetation in a Eucalyptus globulus Labill. coppice as affected by slash management

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    The aim of this study was to assess the effect of different slash management practices on understory biodiversity and biomass in Eucalyptus globulus coppices in Central Portugal. The experiment consisted of four treatments: (a) removal of slash (R), (b) broadcast over the soil (S), (c) as in S but concentrating woody residues between tree rows (W) and (d) incorporation of slash into soil by harrowing (I). Understory vegetation was surveyed during 1–6, 9, and 10 years, the proportion of soil cover by plant species estimated, and diversity and equitability indexes determined. Above ground understory biomass was sampled in years 2–6, 9, and 10. The highest number of species in most years occurred in plots where slash was removed. Differences between treatments in the proportion of plant soil cover were never significant, whereas differences in diversity index were only occasionally significant and apparently related to the number of species. Thus, differences in the equitability index were not significant. Understory biomass did not decrease during the rotation period, and was usually highest in R and I, and lowest in S, but not significantly different. At the end of the rotation period, understory biodiversity indices and biomass were apparently independent of slash treatment

    A classe Cytisetea scopario-striati em Portugal continental

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    Giestais são a designação vulgar em português para as comunidades silicícolas que se inserem na classe Cytisetea scopario-striati e são dominadas por espécies de leguminosas dos géneros Cytisus, Genista, Adenocarpus e Retama. Esta classe tem o seu óptimo na Península Ibérica e representa normalmente as orlas ou etapas de regressão de bosques climácicos da Quercetalia roboris e da Quercion broteroi. No presente trabalho apresentam-se as diversas comunidades da classe Cytisetea scopario-striati que ocorrem em Portugal continental. Propõem-se os seguintes novos sintáxones: Ulici latebracteati-Cytisetum striati cytisetosum grandiflori, Cytiso multiflori-Retametum sphaerocarpae cytisetosum scoparii, Cytiso multiflori-Retametum sphaerocarpae cytisetosum eriocarpi, Cytisetum cabezudo

    A methodological approach to potential vegetation modeling using GIS techniques and phytosociological expert-knowledge: application to mainland Portugal

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    An attempt to obtain a consistent spatial model of natural potential vegetation (NPV) for the mainland Portuguese territory is reported. Spatial modeling procedures performed in a Geographic Information System (GIS) environment, aimed to operationalize phytosociological expert-knowledge about the putative distribution of potential zona1 forest communities dominam in the Portuguese continental territories. The paradigm for NPV assumed was that of RIVAS-MARTINE(1Z9 76) and RIVAS-MARTINEeZt al. (1999), which presupposes, for a given territory, a univocal correspondence between a uniform combination of bioclimatic stage and lithology' gi ven a biogeographical context, and a unique successional sequence leading to a single climax community (i. e. a vegetation series (VS)). Information issued from both literature and a team of phytosociologists possessing detailed knowledge about Portuguese vegetation, namely about forests and its seria1 vegetation, was acknowledged as a starting point for the construction of such a habitat-vegetation correspondence model. First, a bioclimatic map concerning the "Worldwide Bioclimatic Classification System" (WBCS) of RIVAS-MARTINE(1Z9 81 -2004), obtained by multivariate grostatistical interpolation issuing from the work of MESQUITA(2 005), was set. Severa1 partia1 matrices, one for each biogeographical Province, combined such habitat statements to VS. Initial incoherence due to vagueness of statements led to an important amount of both superimposition of VS and habitat gaps in the matrices. Further rearrangement of the table according to known field distribution of VS by experts allowed setting an approximate univocal correspondence VS-habitat. Finally, an intersection of bioclimatic, lithology and biogeographic maps yielded over a thousand habitat combinations to be associated each to a single VS through implementation of the matrices as a set of rules. Again, inconsistencies were solved likewise, but this time by direct observation of the map by experts. Keeping of phytosociological consistency and fidelity to information on actual vegetation field distribution was always mandatory during the proces

    A global view on the riparian forests with Salix neotricha and Populus alba in the Iberian Peninsula (Portugal and Spain)

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    Forests dominated by Salix neotricha, and Populus alba found along the mesoeutrophic rivers in the Iberian Peninsula, were studied. We discuss the floristic circumscription, chorology, and community segregation based on the available releve´s of all Iberian riparian communities included in Populenion albae. Eleven formerly described communities were analyzed and due to original floristic combination, habitat features, and biogeographic scope, a new willow and poplar forest type is proposed within a well-defined biogeographical unit (Sadensean-Dividing Portuguese Subprovince): Clematido campaniflorae- Salicetum neotrichae. This syntaxon is found under a semi-hyperoceanic thermomediterranean to lower mesomediterranean, subhumid to humid bioclimate. Cluster analysis including all Iberian communities of Populenion albae shows a clear floristic segregation within the suballiance and confirms the originality of the new association. Furthermore, chemical characteristics of the water along some of the Portuguese watercourses with Populenion albae were studied and compared to the oligotrophic rivers occupied by Osmundo-Alnion communities. This study suggests that floristic separation between the communities of Populenion and Osmundo-Alnion is accompanied by a differentiation of the water trophic level

    Clear-PEM: A PET imaging system dedicated to breast cancer diagnostics

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    The Clear-PEM scanner for positron emission mammography under development is described. The detector is based on pixelized LYSO crystals optically coupled to avalanche photodiodes and readout by a fast low-noise electronic system. A dedicated digital trigger (TGR) and data acquisition (DAQ) system is used for on-line selection of coincidence events with high efficiency, large bandwidth and small dead-time. A specialized gantry allows to perform exams of the breast and of the axilla. In this paper we present results of the measurement of detector modules that integrate the system under construction as well as the imaging performance estimated from Monte Carlo simulated data.http://www.sciencedirect.com/science/article/B6TJM-4M942B5-D/1/e8aea93baa1aeae3538ea200a5a5466

    Annual dune plant communities in the Southwest coast of Europe

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    This study presents an updated sintaxonomic review of the annual communities from coastal dunes in the Southwest coast of Europe, specifically in the Iberian Peninsula, including both types: directly influenced by the sea salt spray and not affected by this influence. The floristic segregation of the different plant associations was obtained by statistical agglomerative processes (UPGMA, Unweighted Pair Group Method with Arithmetic Mean) plus principal coordinate analysis (PCoA) and discussed based on the interpretation of phytosociological tables. Three new communities in central western Portugal were found and are described: Pseudorlayo minusculae-Polycarpietum alsinifoli, Cerastio diffusae-Vulpietum fontqueranae and Omphalodo kunzinskyanae-Evacietum ramosissimae
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