The phenology of Rhododendron ferrugineum L. (Ericaceae) in correlation to temperature, frost, insolation, and snow cover duration
Schlüssel, André; Theurillat, Jean-Paul; Wiget, Lucie
The phenology of Rhododendron ferrugineum L. has been studied during five years (1994 to 1998) in two sites in the Alps of Valais (Switzerland). The first site is the Val d'Arpette and the second one is Belalp. Observation plots have been set up according to a subalpine-alpine altitudinal transect. Several climatic factors such as air temperature, soil temperature, relative air humidity, insolation and snow cover duration have been measured. The correlation between the phenological development and these factors has been determined. The results show that the floral development of this species is mainly correlated with the sum of the mean daily air temperature. But frost, insolation and snow cover duration have also shown a significant influence. A phenoclimatic model including all these factors is proposed.