Spring phenology of some ornamental species, as an indicator of temperature increase in the urban climate area

Abstract

The aim of this study is to provide information on the phenology of urban spring season, of some species of ornamental trees and shrubs, in the light of climate changes occurred over the recent decades. Ten species of ornamental shrubs and trees cultivated in two areas of a town located in southwestern Romania were studied. It was found that the spring season phenology of the studied species is dependent on the climatic year, in recording differences between the number of days from November 1 and the beginning of each spring phenophase, both from one species to another and from one climatic year to another, and also from one area to another; the spring phenology starting earlier in the urban area regardless of the species and the climatic year. Higher temperatures, rising from one year to another, are speeding-up the onset and development of spring phenology, regardless of species, and the urban climate through the effect of urban heat island leads to even earlier onset of spring phenophases and shortening of the growing season, so that by phenological differences existing within the species from one climatic year to another and from one climatic zone to another, spring season phenology can be considered an indicator of temperature rise.