2017 ASHS Annual Conference

On April 27, 1986, in then-Soviet Ukraine, reactor number four of the Chernobyl nuclear power plant exploded during a test procedure, releasing enormous amounts of radionuclides. All inhabitants of nearby Pripyat (a modern city of 50,000) were evacuated within three days, never to return. In 2016, we compared unmaintained horsechestnut trees (Aesculus hippocastanum L.) in the abandoned town of Pripyat to maintained trees of the same species and age in the city of Kiev, Ukraine. Trees in Kiev were subject to numerous pruning wounds and developed significantly more branch defects in their canopies compared to trees in Pripyat. Kiev trees had more trunk injuries and displayed cankers and decay in their main stems. Kiev trees had larger stem diameters than trees in Pripyat, but overall quality of their form was reduced compared to street trees in Pripyat. Trees in Pripyat were growing in direct competition with invasive tree species that resulted in shading of their lower canopies, significant competition for light and water, and increased deadwood in lower branches. There was abundant leaf litter in the Pripyat trees resulting in a spongy mulch layer with measurable radioactivity. Trees in Kiev were maintained with a clean canopy floor and sparse turfgrass.