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Mineralização do N do solo: caso de estudo num ensaio de plantações mistas de Fraxinus excelsior x Alnus cordata

Pereira, Ermelinda; Caldas, Sandra; Patrício, Maria do Sameiro; Nunes, Luís; Monteiro, Maria do Loreto
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Conferência ou Objeto de Conferência
POR
Relevância na Pesquisa
47.15%
A presença de espécies secundárias fixadoras de N, como é o caso de Alnus cordata, entre outros aspectos, aumenta a fertilidade do solo, reduz a competição, particularmente entre diferentes tipologias radiculares e aéreas e, valoriza a qualidade da madeira da espécie principal (Buresti e Frattegiani, 1995). Neste trabalho avaliou-se a dinâmica da mineralização de N do solo, num ensaio de plantações mistas de Fraxinus excelsior x Alnus cordata, localizado no concelho de Vimioso no Nordeste transmontano, instalado em 1998. A avaliação foi efectuada através do método de incubação sequencial in situ, segundo a metodologia de Raison et al. (1987), durante o período de Abril a Agosto, utilizando-se para o efeito, tubos de aço de 25 cm de comprimento e 5 cm de diâmetro. Para o estudo consideraram-se as parcelas: puro de freixo (Fe), puro de amieiro (Ac) e freixo e amieiro consociado na linha de forma alternada com um compasso de 3,5x2,0m. Em cada parcela foram considerados 4 pontos de amostragem. Os primeiros resultados revelaram que a mineralização líquida de N (N-NH4+ + N-NO3-) variou ao longo do período de estudo não se verificando, contudo, diferenças significativas (p<0,05) entre parcelas, para cada período de incubação. O facto de não se verificarem diferenças significativas leva-nos a concluir que o mecanismo da facilitação...

Mixed forests plantations with naturalized broadleaves and nitrogen fixing species

Monteiro, Maria do Loreto; Caldas, Sandra; Patrício, Maria do Sameiro; Nunes, Luís; Pereira, Ermelinda
Fonte: FAO Publicador: FAO
Tipo: Conferência ou Objeto de Conferência
ENG
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27.15%
Two experimental trials of planted forest were established in Northeast of Portugal, in 1998, concerning the Project PRAXIS XXI – 3/3.2/Flor/2127/95. Each essay is composed by main broadleaves species to produce high quality timber. These species are mixed with secondary N-fixing trees. One trial has thirty six plots concerning twelve diferents treatments with three replications, composed by main species: Prunus avium, Juglans nigra and Fraxinus excelsior, in association with Alnus cordata. The other trial has thirty plots correspondents a ten diferents treatments with three replications, is arranged by main species: Prunus avium, Quercus rubra and Castanea sativa in association with Robinia pseudoacacia. The aim is to study the possible benefits among the production of the main species, the presence of N-fixing species, and so dendrometric data were collected in all plants of each essay. At the same time, the rate of survival of each species was calculated. On the other hand, following Raison et al. (1987) methodology, incubations were performed in situ soil, in order to evaluate the possible profits of nitrogen on the soil, and also its effects of the main species. The results show that the main species grow better in height and diameter when associated with the N-fixing trees...

Mineralização do N do solo: caso de estudo num ensaio de plantações mistas de Fraxinus excelsior x Alnus cordata

Pereira, Ermelinda; Caldas, Sandra; Patrício, Maria do Sameiro; Nunes, Luís; Monteiro, Maria do Loreto
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Conferência ou Objeto de Conferência
POR
Relevância na Pesquisa
47.15%
Em 1998 instalou-se um ensaio experimental de povoamentos mistos com espécies folhosas, produtoras de madeira de qualidade, consociadas com espécies secundárias fixadoras de azoto, com o objectivo de estudar os possíveis benefícios sobre a espécie objectivo. Neste contexto, procedeu-se à avaliação da dinâmica do N no solo, pela quantificação dos fluxos de mineralização/imobilização, através do método de incubação sequencial in situ, nas consociações Fraxinus excelsior x Alnus cordata.

LC-DAD/ESI-MS/MS study of phenolic compounds in ash (Fraxinus excelsior L. and F. americana L.) heartwood. Effect of toasting intensity at cooperage

Sanz, Miriam; Fernandez de Simon, Brigida; Cadahia, Estrella; Esteruelas, Enrique; Munoz, Angel M.; Hernandez, Teresa; Estrella, Isabel; Pinto, Ernani
Fonte: WILEY-BLACKWELL; HOBOKEN Publicador: WILEY-BLACKWELL; HOBOKEN
Tipo: Artigo de Revista Científica
ENG
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67.65%
The phenolic composition of heartwood extracts from Fraxinus excelsior L. and F. americana L., both before and after toasting in cooperage, was studied using LC-DAD/ESI-MS/MS. Low-molecular weight (LMW) phenolic compounds, secoiridoids, phenylethanoid glycosides, dilignols and oligolignols compounds were detected, and 48 were identified, or tentatively characterized, on the basis of their retention time, UV/Vis and MS spectra, and MS fragmentation patterns. Some LMW phenolic compounds like protocatechuic acid and aldehyde, hydroxytyrosol and tyrosol, were unlike to those for oak wood, while ellagic and gallic acid were not found. The toasting of wood resulted in a progressive increase in lignin degradation products with regard to toasting intensity. The levels of some of these compounds in medium-toasted ash woods were much higher than those normally detected in toasted oak, highlighting vanillin levels, thus a more pronounced vanilla character can be expected when using toasted ash wood in the aging wines. Moreover, in seasoned wood, we found a great variety of phenolic compounds which had not been found in oak wood, especially oleuropein, ligstroside and olivil, along with verbascoside and isoverbascoside in F. excelsior, and oleoside in F. americana. Toasting mainly provoked their degradation...

Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica)

Jacob, Mascha; Viedenz, Karin; Polle, Andrea; Thomas, Frank M.
Fonte: Springer-Verlag Publicador: Springer-Verlag
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.15%
We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific (pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter of the other tree species (except for Acerplatanoides) revealed a “home field advantage” of up to 20% (more rapid litter decomposition in stands with a high fraction of its own species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed additive characteristics...

Presence of natural genetic resistance in Fraxinus excelsior (Oleraceae) to Chalara fraxinea (Ascomycota): an emerging infectious disease

McKinney, L V; Nielsen, L R; Hansen, J K; Kjær, E D
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.31%
Fraxinus excelsior, common ash native to Europe, is threatened by a recently identified pathogenic fungus Chalara fraxinea, which causes extensive damage on ash trees across Europe. In Denmark, most stands are severely affected leaving many trees with dead crowns. However, single trees show notably fewer symptoms. In this study, the impact of the emerging infectious disease on native Danish ash trees is assessed by estimating presence of inherent resistance in natural populations. Disease symptoms were assessed from 2007 to 2009 at two different sites with grafted ramets of 39 selected clones representing native F. excelsior trees. A strong genetic variation in susceptibility to C. fraxinea infections was observed. No genetic or geographic structure can explain the differences, but strong genetic correlations to leaf senescence were observed. The results suggest that a small fraction of trees in the Danish population of ash possess substantial resistance against the damage. Though this fraction is probably too low to avoid population collapse in most natural or managed ash forests, the observed presence of putative resistance against the emerging infectious disease in natural stands is likely to be of evolutionary importance. This provides prospects of future maintenance of the species through natural or artificial selection in favour of remaining healthy individuals.

Adaptive potential of ash (Fraxinus excelsior) populations against the novel emerging pathogen Hymenoscyphus pseudoalbidus

Kjær, Erik Dahl; McKinney, Lea Vig; Nielsen, Lene Rostgaard; Hansen, Lars Nørgaard; Hansen, Jon Kehlet
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.41%
An emerging infectious pathogen Hymenoscyphus pseudoalbidus has spread across much of Europe within recent years causing devastating damage on European common ash trees (Fraxinus excelsior) and associated plant communities. The present study demonstrates the presence of additive genetic variation in susceptibility of natural F. excelsior populations to the new invasive disease. We observe high levels of additive variation in the degree of susceptibility with relatively low influence of environmental factors (narrow-sense heritability = 0.37–0.52). Most native trees are found to be highly susceptible, and we estimate that only around 1% has the potential of producing offspring with expected crown damage of <10% under the present disease pressure. The results suggest that the presence of additive genetic diversity in natural F. excelsior populations can confer the species with important ability to recover, but that low resistance within natural European populations is to be expected because of a low frequency of the hypo-sensitive trees. Large effective population sizes will be required to avoid genetic bottlenecks. The role of artificial selection and breeding for protection of the species is discussed based on the findings.

Estimating Coextinction Risks from Epidemic Tree Death: Affiliate Lichen Communities among Diseased Host Tree Populations of Fraxinus excelsior

Jönsson, Mari T.; Thor, Göran
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 25/09/2012 EN
Relevância na Pesquisa
47.47%
At least 10% of the world’s tree species are threatened with extinction and pathogens are increasingly implicated in tree threats. Coextinction and threats to affiliates as a consequence of the loss or decline of their host trees is a poorly understood phenomenon. Ash dieback is an emerging infectious disease causing severe dieback of common ash Fraxinus excelsior throughout Europe. We utilized available empirical data on affiliate epiphytic lichen diversity (174 species and 17,800 observations) among 20 ash dieback infected host tree populations of F. excelsior on the island Gotland in the Baltic Sea, Sweden. From this, we used structured scenario projections scaled with empirical data of ash dieback disease to generate probabilistic models for estimating local and regional lichen coextinction risks. Average coextinction probabilities (Ā) were 0.38 (95% CI ±0.09) for lichens occurring on F. excelsior and 0.14 (95% CI ±0.03) when considering lichen persistence on all tree species. Ā was strongly linked to local disease incidence levels and generally increasing with lichen host specificity to F. excelsior and decreasing population size. Coextinctions reduced affiliate community viability, with significant local reductions in species richness and shifts in lichen species composition. Affiliates were projected to become locally extirpated before their hosts...

Long-Term Effect of an Aqueous Fraxinus excelsior L. Seed Extract in Spontaneously Hypertensive Rats

López-Carreras, Noemi; Fernández-Vallinas, Sandra; Miguel, Marta; Aleixandre, Amaya
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.15%
The effect of long-term intake of different doses (20, 40, and 60 mg/kg/day) of a Fraxinus excelsior L. seed extract (FESE) on spontaneously hypertensive rats (SHR) was evaluated. Water was used as control and captopril (50 mg/kg/day) was used as positive control. Systolic blood pressure, body weight, and food and liquid intake were registered weekly in SHR. The antioxidant and vascular relaxing properties of FESE were also studied in these animals. The development of hypertension was attenuated in the groups treated with captopril or FESE. The antihypertensive effect was more accentuated in the captopril group than in the FESE groups, and it was paradoxically more accentuated in the groups treated with 20 mg/kg/day or 40 mg/kg/day of FESE than in the group treated with the highest dose of this extract. Body weight gain and food intake increased in the FESE groups. After removing the corresponding antihypertensive treatment, the arterial blood pressure and the body weight of the FESE treated animals returned to control values. In addition, FESE increased plasma antioxidant capacity and decreased plasma and liver malondialdehyde levels. Moreover, acetylcholine relaxation improved in the aorta rings from the FESE treated rats.

Apoplastic and symplastic phloem loading in Quercus robur and Fraxinus excelsior

Öner-Sieben, Soner; Lohaus, Gertrud
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.15%
Concentration gradients of sugars between the cytosol of mesophyll cells and the phloem reveal that Quercus robur is probably an apoplastic phloem loader and Fraxinus excelsior a mixed phloem loader.

Seasonal Pattern of Lesion Development in Diseased Fraxinus excelsior Infected by Hymenoscyphus pseudoalbidus

Bengtsson, Stina Barbro Katrin; Barklund, Pia; von Brömssen, Claudia; Stenlid, Jan
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 23/04/2014 EN
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36.85%
Ash dieback is a recent widespread disease on ash (Fraxinus sp.) that is causing important economic and ecological losses throughout Europe. The disease is initiated by the ascomycetous fungus Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea). The main aim of this study was to investigate seasonal pattern of lesion development associated with ash dieback. We present data on the spread of 324 natural lesions in ash shoots, branches and stems surveyed over a 32 month period. Most lesions were active and showed the greatest rate of growth during the summer; however, lesions were active throughout the year. Tree mortality was high, with more than a third of the surveyed trees dying during the study. Although many lesions permanently ceased to develop, the rate at which new lesions emerged was greater than the rate at which lesions entered a resting phase. The most common cause for a lesion going into a permanent state of rest was that it had encountered a branch-base. Genotype analysis showed that multiple infections can occur in a single tree given that different genotypes were identified in different lesions as well as in single lesions. A weak positive correlation was noted between tree health and tree size and a weak negative correlation was noted between tree overall health and lesion activity. The lower limit for H. pseudoalbidus growth in culture was between 4.0°C and 0.5°C.

Thank you for not flowering: conservation genetics and gene flow analysis of native and non-native populations of Fraxinus (Oleaceae) in Ireland

Thomasset, M; Hodkinson, T R; Restoux, G; Frascaria-Lacoste, N; Douglas, G C; Fernández-Manjarrés, J F
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
37.31%
The risks of gene flow between interfertile native and introduced plant populations are greatest when there is no spatial isolation of pollen clouds and phenological patterns overlap completely. Moreover, invasion probabilities are further increased if introduced populations are capable of producing seeds by selfing. Here we investigated the mating system and patterns of pollen-mediated gene flow among populations of native ash (Fraxinus excelsior) and mixed plantations of non-native ash (F. angustifolia and F. excelsior) as well as hybrid ash (F. excelsior × F. angustifolia) in Ireland. We analysed the flowering phenology of the mother trees and genotyped with six microsatellite loci in progeny arrays from 132 native and plantation trees (1493 seeds) and 444 potential parents. Paternity analyses suggested that plantation and native trees were pollinated by both native and introduced trees. No signs of significant selfing in the introduced trees were observed and no evidence of higher male reproductive success was found for introduced trees compared with native ones either. A small but significant genetic structure was found (φft=0.05) and did not correspond to an isolation-by-distance pattern. However, we observed a significant temporal genetic structure related to the different phenological groups...

Characterization, localization, and seasonal changes of the sucrose transporter FeSUT1 in the phloem of Fraxinus excelsior

Öner-Sieben, Soner; Rappl, Christine; Sauer, Norbert; Stadler, Ruth; Lohaus, Gertrud
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
47.15%
In Fraxinus excelsior the sucrose transporter FeSUT1 is located in the phloem and involved in apoplastic sucrose loading and retrieval. The expression of FeSUT1 is higher under low sucrose conditions.

Historical and contemporary mating patterns in remnant populations of the forest tree fraxinus excelsior L

Bacles, C.; Burczyk, J.; Lowe, A.; Ennos, R.
Fonte: Soc Study Evolution Publicador: Soc Study Evolution
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
Relevância na Pesquisa
67.46%
Genetic variation at microsatellite markers is used to quantify genetic structure and mating behavior in a severely fragmented population of the wind-pollinated, wind-dispersed temperate tree Fraxinus excelsior L. It is assessed whether habitat fragmentation leads to increased inbreeding, reduced gene flow, and reduced genetic diversity in the species.; Cecile F.E. Baclse, Jaroslaw Burczyk, Andrew J. Lowe and Richard A. Ennos.

Virulence of Hymenoscyphus albidus and H. fraxineus on Fraxinus excelsior and F. pennsylvanica

Kowalski, Tadeusz; Bilański, Piotr; Holdenrieder, Ottmar
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 30/10/2015 EN
Relevância na Pesquisa
47.89%
European ash (Fraxinus excelsior) is currently battling an onslaught of ash dieback, a disease emerging in the greater part of its native area, brought about by the introduction of the ascomycete Hymenoscyphus fraxineus (= Hymenoscyphus pseudoalbidus). The closely-related fungus Hymenoscyphus albidus, which is indigenous to Europe, is non-pathogenic when in contact with F. excelsior, but could pose a potential risk to exotic Fraxinus species. The North American green ash (Fraxinus pennsylvanica) is planted widely throughout Europe and regenerates naturally within this environment but little is known about the susceptibility of this species to ash dieback. We performed wound inoculations with both fungi (nine strains of H. fraxineus and three strains of H. albidus) on rachises and stems of F. excelsior and F. pennsylvanica under field conditions in Southern Poland. Necrosis formation was evaluated after two months on the rachises and after 12 months on the stems. After inoculation of H. albidus, only small lesions (of up to 1.3 cm in length) developed on the F. excelsior and F. pennsylvanica rachises, but with no significant distinction from the controls. Hymenoscyphus albidus did not cause necrotic lesions on the stems of either Fraxinus species. In contrast...

Fraxinus excelsior

Mark E. Olson
Fonte: Universidade Nacional Autônoma do México Publicador: Universidade Nacional Autônoma do México
Tipo: imagen
Relevância na Pesquisa
47.15%

Fraxinus excelsior

Mark E. Olson
Fonte: Universidade Nacional Autônoma do México Publicador: Universidade Nacional Autônoma do México
Tipo: imagen
Relevância na Pesquisa
47.15%

Fraxinus excelsior

Mark E. Olson
Fonte: Universidade Nacional Autônoma do México Publicador: Universidade Nacional Autônoma do México
Tipo: imagen
Relevância na Pesquisa
47.15%

SB-ROBUR+H A Simulator for Four Even-Aged Self-Thinned Stands of Quercus robur and Another Hardwood

Barreto,Luís Soares
Fonte: Unidade de Silvicultura e Produtos Florestais Publicador: Unidade de Silvicultura e Produtos Florestais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2002 PT
Relevância na Pesquisa
47.15%
Recorrendo ao seu modelo conceptual para a competição entre árvores, o autor propõe um simulador para os seguintes povoamentos auto-desbastados e regulares: Quercus robur+Acer pseudoplatanus, Quercus robur+Betula pendula, Quercus robur+Fagus sylvatica, Quercus robur+Fraxinus excelsior. Dada a próxima competitividade das espécies de cada povoamento, o simulador SB-ROBUR+H utiliza equações de Gompertz para simular a dinâmica do número de árvores de cada população. Apresenta-se a listagem do simulador, escrita em BASIC, e uma amostra da sua saída.

SB-BACO4: A Gompertzian Discrete Model for Tree Competition

Barreto,Luís Soares
Fonte: Unidade de Silvicultura e Produtos Florestais Publicador: Unidade de Silvicultura e Produtos Florestais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2003 EN
Relevância na Pesquisa
47.15%
For interspecific competition between tree populations, the author proposes a discrete Gompertzian model named SB-BACO 4. The model is a direct extension of a discrete form of the Gompertz equation. Both deterministic and stochastic versions are exhibited. The model is capable of the correct recognition of six distinct patterns of tree interaction, previously defined by the author. He uses model SB-BACO 4 to establish the simulator SB-PINHARDI for mixed stands of Quercus robur+Pinus pinaster and Fraxinus excelsior+Pinus pinaster. In appendices, the author presents the listing of the program, written in BASIC, and a sample of its output. A general Gompertzian explicit model for tree competition is also presented (SB-BACO 5).