Analysis of the grass (Poaceae L.) pollen seasons in Wrocław, 2003-2010

The aim of the study was to analyse the grass pollen season dynamics in Wrocław in 2003-2010. The studies were carried out using volumetric method (Burkard trap). Special attentions was paid to differences in pollen season duration and patterns. The pollen season started on average on the 130th day of the year (±10 days) and ended on the 240th (±11 days). Peak of pollen seasons occurred between 156th and 185th day of the year. The mean of SPI value was 2805 (±380). On average, 18 days (±4 days) with a grass pollen concentration of more than 50 grains × m-3, and 2 days (±1 day) with concentration of more than 120 grains × m-3 were recorded during the seasons analysed. Three types of pollen seasons were distinguished on the basis of cluster analysis (the non-hierarchical method of multifeature clustering - the k-means method)