Birch in blossom earlier this year - News and Discussion - European Phenology Campaign

Report from Lenka Hajkova, phenology scientist from Czech Hydrometeorological Institute:

The birch (Betula pendula), was already blooming and the leaves were out in the lowlands of Czech Republic during the second week of April. In most of the places the flower buds were developed couple of days earlier this year as compared to the long-term average data. The inflorescence emergence (which in phenological terms is the first indicator of blossoming onset) was observed in Lednice, south of the country, on March 28th, which is 5 days earlier, and then at lowlands near the River Elbe in Doksany on 2nd April and was 12 days early when compared to long term average. At a slightly higher altitude, the records show that birch started to blossom during the first week of April, for some stations that means 2-3 weeks earlier than the average.

The birch pollen is a significant allergen and at the same time it can induce an allergic reaction after mixing with other pollen types. The size of the pollen grains on an average is around 20-30 µm. The distribution of pollen in the air is affected by ongoing weather conditions. If the weather is sunny and windy during birch blossoming, concentration of pollen in the air increases with sunny days whereas if it is rainy and humid, the pollen gets washed from the atmosphere by precipitation and its concentration drops significantly. If the weather suddenly turns cold and the air temperature drops, the blossoming process slows down making the pollen season to last longer.
 
Which phenology phase is a birch in your country in now?

What date did you see it blossoming?

What is the link between the blossoming or greening up of birch and the current weather in your country?
 
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