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  • 1
    Electronic Resource
    Electronic Resource
    Selecting models to predict the timing of flowering of temperate trees: implications for tree phenology modelling (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Classical budburst models (Spring Warming, Sequential, Parallel and Alternating) are unable to fully predict external data, partly because of the methods of optimization used to adjust them. The purpose of this study was to examine different assumptions of budburst models and select those which are best supported by the data, defining new models able to predict external data. Eight models, each differing in one assumption, were fitted and tested using external data. The dataset used to test the models was deduced from aeropalynological data at two stations in France. The results show that some of the models proposed are able to accurately predict external dates of flowering of most of the studied species. The assumptions of those models have been individually tested and shown to improve the models accuracy. Robust estimates of the best predictor models of 12 tree species are presented. The analysis of hypothetical provenance transfer of two species, Buxus sempervirens and Platanus acerifolia, between the two study sites, shows that P. acerifolia estimates are similar in both environments whereas B. sempervirens estimates are variable. This result, which agrees with the genetic characteristics of both species, shows that local adaptation of phenology can also be studied through modelling approaches.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1999.00395.x
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  • 2
    Electronic Resource
    Electronic Resource
    Fitting models predicting dates of flowering of temperate-zone trees using simulated annealing (1998)
    Oxford, UK : Blackwell Science Ltd, UK
    Plant, cell & environment 21 (1998), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The aim of the present study was to test the four commonly used models to predict the dates of flowering of temperate-zone trees, the spring warming, sequential, parallel and alternating models. Previous studies concerning the performance of these models have shown that they were unable to make accurate predictions based on external data. One of the reasons for such inaccuracy may be wrong estimations of the parameters of each model due to the non-convergence of the optimization algorithm towards their maximum likelihood. We proposed to fit these four models using a simulated annealing method which is known to avoid local extrema of any kind of function, and thus is particularly well adapted to fit budburst models, as their likelihood function presents many local maxima. We tested this method using a phenological dataset deduced from aeropalynological data. Annual pollen spectra were used to estimate the dates of flowering of the populations around the sampling station. The results show that simulated annealing provides a better fit than traditional methods. Despite this improvement, classical models still failed to predict external data. We expect the simulated annealing method to allow reliable comparisons among models, leading to a selection of biologically relevant ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00299.x
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  • 3
    Electronic Resource
    Electronic Resource
    Allergy in the Mediterranean area I. Pollen counts and pollinosis of Montpellier (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical & experimental allergy 14 (1984), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The climatic conditions of the Mediterranean area results in vegetation and pollen very different from that of the other parts of Europe. The pollen content of the atmosphere of Montpellier, southern France, was examined using a filter sampler which was shown to be more efficient than most of the current devices for air sampling. Pollen counts were subsequently compared with pollinosis of patients born and living in and around Montpellier. The mean annual pollen counts showed that grass pollens and Cupressaceae pollens (cypress and juniper) are the highest. Some Mediterranean pollens (Oleaceae, London plane, Parietaria) are also important. Plantain and oak pollens are also present in relatively large amounts.Grass pollen allergy was found to be present in 86.5% of pollen-allergic patients. It was followed by plantain, Parietaria, Oleaceae, London plane and Cupressaceae pollens which were allergenic in 13-36% of pollen-allergic patients. Oak and pine pollens were present in large quantities in the counts but few persons were sensitive to oak and none to pine. By contrast, some patients had positive skin tests to alfalfa, red clover, acacia and lime tree pollens though these pollens were almost absent from the counts. In a few cases local sources of these pollens could account for the positive skin tests but cross-sensitivities could also occur. In summary, pollinosis of the Northern Mediterranean area is intermediate between the southern part of the area and the other parts of Europe.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.1984.tb02204.x
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  • 4
    Electronic Resource
    Electronic Resource
    Heterogeneity of atopy. I. Clinical and immunologic characteristics of patients allergic to cypress pollen (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Allergy 48 (1993), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The heterogeneity of pollen-allergic persons is well known but poorly characterized. Cypress is one of the major pollen-producing plants of the Mediterranean area. A study was undertaken to characterize the symptoms presented by patients allergic to cypress pollen and the heterogeneity of the IgE immune response between patients allergic only to cypress pollen and those who are polysensitized. Eighty-nine patients allergic to cypress pollen were studied, 26 being allergic only to cypress pollen. The IgE response was assessed by skin prick tests and the titration of serum total IgE and cypress-specific IgE by RAST. Clinical reactivity was assessed by symptom scores during the cypress pollen season and skin tests. Pollen counts were obtained. The clinical reactivity was similar in both patient groups. Rhinitis was present in all patients, conjunctivitis in 73.7–88.5%, and asthma in only 7.4–19.2%. The age of onset of symptoms caused by cypress pollen allergy was significantly greater in patients allergic to cypress pollen only. Total serum IgE was within the normal range in the cypress pollen group and significantly lower than in the polysensitized groups. Cypress pollen RAST was higher in the polysensitized group. We concluded that conjunctivitis is particularly common in cypress pollen allergy. Patients allergic only to cypress pollen may be unique in their way of expressing serum total IgE levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.1993.tb00711.x
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  • 5
    Electronic Resource
    Electronic Resource
    Climatic calibration of 80 aeropollinic taxa along a European transect (1993)
    Springer
    Plant ecology 109 (1993), S. 107-124 
    Details
    ISSN: 1573-5052
    Keywords: Sum of temperatures ; Abundance ; Indicator ; Probabilities ; Estimation of the climate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The aim of calibration is to measure the relationships between climate and taxa, in order to use the taxa as indicators for the estimation of bioclimates. The indicator capacity of a taxon (ICT) measures the probability of two events, together or separately, either the ordering of abundance, within the range of a factor, or the confining of presences inside a limited part of the range. ICT is obtained from numbering inequalities or matches, on such orderings, without any arithmetical operation upon the initial data. ICT measures the indicator capacity of a taxon for a factor, even if the taxon is intermittent or if its gradient is irregular. ICT increases with the threshold of the sum of temperatures, for some taxa, such as Arbutus, Celtis, Cistus, Coriaria, Cupressaceae, Helianthemum, Olea, Onobrychis, Pistacia, Silene, Thymelaeaceae. These taxa indicate a superior threshold above the classical one of 0 °C. Conversely, ICT decreases when the threshold increases, for other taxa, such as Abies, Aesculus, Fraxinus, Juglans, Mercurialis, Populus, Resedaceae, Salix, Thalictrum, Tilia. A taxon may be an indicator for the whole range of a temperature, if its abundance increases rather regularly, such as Chenopodiaceae, Erica, Olea, Plantago, Tamarix, Umbelliferae, Vitis, or if its abundance decreases, as for Betula, Filicidae, Fraxinus, Juglans, Tilia. Conversely, some other taxa are indicators only in a part of the range, such as Calluna, Galium and Platanus. The indicator capacity is used to estimate the thermic climate according to the flora. For each taxon, ICT depends on A and F, which are the ranks of abundance and thermal factor. For a given rank A, observed in a spectrum, ICT depends on F; ICT is the probability of the spectrum to be in the rank F. The maximum value of ICT, for all taxa in the spectrum, indicates the probable rank of that spectrum. Along the transect, the estimated temperatures happen to be equal to the measured ones for all the tested spectra (except one) and for all the factors, even if a small part of the flora is tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00044744
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  • 6
    Electronic Resource
    Electronic Resource
    A probabilist model of the relations between pollen and climate and its application to 80 European annual spectra (2000)
    Springer
    Plant ecology 147 (2000), S. 147-163 
    Details
    ISSN: 1573-5052
    Keywords: Accuracy ; Concentration ; Indicator ; Intermittence ; Ordering ; Stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relation between pollen and climate is commonly computed by regressing the climatical factor. The disadvantage of this method is that it does not respect the ordinal and intermittent nature of field data. This paper overcomes the artefacts created by this problem by using a probabilist calibration, that quantifies the ecological linkage between a taxon T and a factor with a general parameter, the probability PROX for an abundance A being confined near the rank F of the factor. Confining simulates the effect of the factor upon the concentration of presences and ordering of abundances, and calibrates the climatical behaviour of a taxon with the set of PROX for all possible pairs (A,F). It summarizes a behaviour with the probable position of each abundance A in the range of the factor. Calibration was applied to 130 pollen taxa observed in a network of 80 standardized annual aeropollinic spectra. Spectra were mostly from France, the rest being from a transect stretching from Sweden to Algeria. Spectra were characterized by the values of 10 climatic factors, as well as the presence and abundance of 130 pollen taxa. The influence of geographical climate differences upon pollen content in the atmosphere was quantified by comparing the spectra. Pairs from different localities but the same year were compared. The reliability of indicator taxa was tested by estimating the climate in the 80 spectra using calibration. For all the taxa observed in a spectrum, the envelope of confinings generally followed an unimodal gradient, whose mode was the probable position of the spectrum. Reliability of the estimate was measured by its accuracy, being the agreement between estimates and measures; and by its stability, being the agreement between two estimates from the same climate according to two different flora (the two halves of a spectrum for instance). Average accuracy was 72%, and average stability 87%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009897822424
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