Long term response of Tillia cordata and Tillia tomentosa vegetation period in central Lithuania

Abstract

Climate warming determines significant changes in plant phenology of temperate latitudes, thus making great impact on the duration of vegetation period. These changes are important in the context of plant species migration from their natural habitats. Silver (Tilia tomentosa Moench.) and small-leaved linden (Tilia cordata Mill.) are most popular linden in European cities. The aim of this study was to estimate the response of linden (T. cordata and T. tomentosa) vegetation period to changing climate in 1973–2018 in central Lithuania. Long-term observation of linden phenology was carried out by dendrologists of Botanical Garden of Vytautas Magnus University. Data of small-leaved and silver linden phenology in paper archives were available from 1973 for both species. Possible error of observed phenological events was ±5 days. Data of mean monthly air temperature (oC) and precipitation amount (mm) were obtained from Kaunas meteorology station archives. Changes in 1973–2018 were approximated by linear trend method, taking the values in the beginning (start date) and the end (end date). The change of mean annual air temperature in 1973–2018 was equal +1.83 °C (p < 0.05), and the change of annual precipitation amount – +9.18 (mm) (p > 0.05). In 1973–2018 mean annual temperature in the environment of sample linden rose by 0.04 °C per year. Mean vegetation period of small-leaved linden continued 207 ± 2.5 days and of silver linden – 214 ± 2.6 days in 1973–2016 year period. Bud swelling phenophase of small-leaved linden on average started on the 2nd of April and leaves ended falling on the 25th of October, while silver linden’s bud swelling phenophase on average started one day earlier and the end of leave falling finished 5.5 days later. Vegetation period of T. cordata prolonged by 19.40 days and 25.52 days for T. tomentosa [...]