Pollen concentration of invasive tree of heaven (Ailanthus altissima) on the Northern Great Plain, Hungary

In areas where the tree of heaven (Ailanthus altissima) appears and multiplies, the original vegetation degrades and transforms. The invasive tree of heaven is also of great importance in urban environments, where it causes building damage, static problems and endangers utilities. Ailanthus pollen concentration was measured during the 3-year period (2016-2018) at three county capitals (Szolnok, Debrecen, Nyíregyháza) of the Northern Great Plain, Hungary (JászNagykun-Szolnok county, Hajdú-Bihar county and Szabolcs-Szatmár-Bereg county), with a 7-day Hirst-type (Burkard) pollen trap. The highest total pollen count of A. altissima was measured in all three years in Nyíregyháza (1114 pollen m-3 in 2016; 788 pollen m-3 in 2017; 635 pollen m-3 in 2018), while the lowest values were measured in Szolnok in all three years (99 pollen m-3 in 2016; 78 pollen m-3 in 2017; 93 pollen m-3 in 2018). In Debrecen, the annual total pollen concentration varied between 109-127 pollen grains m-3 in the studied period. The extent of the prevalence of A. altissima can be deduced from its pollen concentrations. For this purpose, multi-year pollen data is displayed on a map in which areas characterized by different pollen concentrations are represented by colour codes. Pollen monitoring provides information on the size of A. altissima stands and provides a basis for proposals and plans for measures to control this invasive tree species and mitigate the damage caused by it.