CR 30:21-28 (2005)  -  doi:10.3354/cr030021

ABSTRACT: The temperature response of long-term phenological records covering the whole 20th century was studied for 8 stations across Germany and for 3 phenophases (beginning of flowering in the horse chestnut Aesculus hippocastanum L., lilac Syringa vulgaris L., and red currant Ribes rubrum L.). Two different climate data sets were used: monthly mean temperatures for the 20th century for Germany from a Tyndall Centre data set (TYN) and a local climate data set from climate stations operated by the Deutscher Wetterdienst (German weather service, DWD) adjacent to the phenological stations. Linear regression of flowering onset and spring temperatures (March, April) revealed that, in general, a 1°C increase in temperature resulted in advances of flowering dates of 2.6 to 6.9 d, with a stronger temperature response rate at climate stations with higher spring temperatures and subsequent earlier spring onset. The effects of choosing local or national mean temperatures were small. Whilst a linear relationship between spring onset dates and temperature is generally indicated, this linearity of response might not be valid over the whole temperature range. The linear response rates at single stations (DWD) decreased towards cooler stations with later onsets, and for almost all stations there was a slightly reduced response at the cooler end of the temperature range (TYN). In most cases, the response rates of flowering onset to variations in temperature (TYN) did not differ significantly between the first and the second half of the 20th century; thus, there are no indications of adaptation processes.

KEY WORDS: Response · Temperature · Temperature response rate · Phenology · Germany · Climate change