Predicting the intensity of the birch pollen season |
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Authors: | Åslög Dahl Sven-Olov Strandhede |
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Institution: | (1) Department of Systematic Botany, Carl Skottsbergs gata 22B, S-413 19 Gothenburg, Sweden |
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Abstract: | We present a model for the prediction of the magnitude ofBetula flowering and pollen dispersal which may be used in the management of birch pollinosis and in the planning of clinical trials.
The pollen sum during the flowering season is regressed on the temperature sum from May 1st to July 20th during the initiation
year, the pollen sum of the initiation year, and the temperature sum during the main pollen season in the flowering year.
We suggest that the fluctuating flowering pattern inBetula alba-species is primarily determined by the availability of assimilation products during inflorescence initiation and development
during the spring one year before anthesis. When inflorescences, which are initiated during the previous year, elongate in
the beginning of anthesis, they act as strong sinks to stored carbohydrates, and thus compete with developing leaves and shoots.
The result is an initially reduced photosynthetic capacity in years with intense flowering, and a limited potential for the
initiation of new inflorescences for the following year. The ambient temperature during catkin initiation affects assimilation
efficiency and is a determinant of about equal importance to flowering intensity as is the magnitude of the flowering in the
initiation year. The amount of pollen dispersed is also dependent on the weather during anthesis, which is not possible to
predict until about one month in advance. The two other independent variables are available during the previous summer, making
it possible to give a sufficiently valid prediction to allergologists about the magnitude of the next birch pollen season,
according to its botanical determinants. We suggest that the varying reproductive output inBetula alba should not be described as true masting. A more parsimonious explanation to the flowering pattern is that an individual continually
maximizes reproductive effort, according to what is possible, but that reproduction is often constrained by the environment. |
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Keywords: | Betula L Mast flowering Prediction model Pollen season Pollinosis Aerobiology |
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