Observed changes in the onset of phenophases at the International Phenological Garden in Doksany

International Phenological Gardens (IPG) were established to collect comparable phenological data across Europe. In each IPG, genetically identical clones of trees and shrubs are planted according to a standardized plan and methodology. This allows a more precise analysis of phenological development and better identification of the effects of environmental factors, such as air temperature, precipitation, and photo-period, on phenological phenomena, being important for understanding the response of ecosystems to environmental changes. The IPG in Doksany was established in 2000 (tree planting) and phenological observations began in the following year (2001). The phenological results of three species (common hazel, downy birch and bird cherry) were evaluated for the period 2001–2025, and the Mann-Kendall test was used to determine trends in the time series. It has been found that the phenological phases are shifting to earlier periods of the growing season, and in the case of hazel even to the winter months in some years. The earlier onset of the phenological phases of woody species follows an increase in air temperatures in the winter and spring periods. The presented analysis illustrate the significant connection between air temperature and the onset of phenological phases. The use of a digital camera at the IPG station in monitoring phenophases is an obvious advantage contributing to the accuracy and objectivity of the observed data.