Pflanzenphänologische Beobachtungen in Graubünden: Trends bei pflanzenphänologischen Zeitreihen | Phytophenological observations in the Grisons:Trends of phytophenological time series

Statistical analyses were carried out using data from 25 phenological observation stations in the Grisons and 17 chosen phenological phases between 1951 and 1998. Results show a wide scattering of phenological data depending on both time and location. The variation is attributable to climate differences in the different regions (Rheinbünden, Südbünden and Engadin), as well as differences of altitude (between 580 and 1805 m.a.s.l.) in the Canton. Trend analyses of 100 phenological time series during the period in question show, above all, a precocious tendancy in the Grisons. In contrast to the evaluation for the whole of Switzerland all phenophase species(including autumnal phases) show a precocious trend which reaches a peak at 22 days in full blossom. This early start of the vegetation period is cleary linked to climate change, as the start of phenological phases in spring are strongly influenced by temperature. Generally speaking, precocity in the Grisons is more accentuated than in the rest of Switzerland. This is a persuasive result in view of the fact that plants at the higher stations react more strongly to climate warming than those in the lowlands or in milder regions and many of the observation stations in the Grisons are situated at alpine altitudes, i.e., over 1000 m.a.s.l.