Swiss spring plant phenology 2007: Extremes, a multi‐century perspective, and changes in temperature sensitivity

Abstract

Spring (March–May) 2007 was characterized by record high temperatures over European land areas. Anomalously high temperatures led to a very early onset of plant phenological spring phases, including 98 record early observations out of a possible total of 302 (32%) for selected phases in Switzerland. In the context of the last 300 years and based on three tree species, 2007 marks the third earliest, after 1961 and 1794, plant phenological spring onset in Switzerland. We show that the temperature sensitivity of Swiss plant phenology to spring temperatures has changed within the last three centuries: sensitivity has generally increased over the record period but also decreased during two periods with warming trends (1890–1950; 1970–2007).

Long-term linear trends mask phenological shifts

“…However, they provided no explanation for this increase and did not quantify the intensity of chilling during this extended period. In addition, it should be noted that previous analyses of phenological data since 1753 in Switzerland also suggested long-term changes in ST based on 30-year windows (Rutishauser et al 2008). This result actually supports our conclusion that changes in the number of chilling days can elicit changes in ST. As shown in Fig.…”

Geographical pattern in first bloom variability and its relation to temperature sensitivity in the USA and China

“…Following the previous studies (Dai et al 2013;Fitter and Fitter 2002;Ge et al 2014b;Rutishauser et al 2008), temperature sensitivity of spring phenology was computed as a slope coefficient of linear regression between FBD and mean preseason temperature at the nearest meteorological station on the interannual timescale. Since the temperature sensitivity of FBD based on different preseason length (e.g., 45 or 90 days) was well correlated with each other (R>0.8, P<0.001, data not shown), the preseason period lengths had little impact on the results.…”

Extreme grape harvest data of Austria, Switzerland and France from A.D. 1523 to 2007 compared to corresponding instrumental/reconstructed temperature data and various documentary sources

“…Chuine et al (2004), Meier et al (2007), Rutishauser et al (2008) and Leijonhufvud et al (2008Leijonhufvud et al ( , 2010. Rainy weather conditions, social traditions, commercial decisions or warfare give rise to uncertainties, which can hardly be assessed.…”

“…Indeed, Rutishauser et al (2008) point out that the temperature sensitivity of plant phenology alters in the course of centuries due to other long-term influences, like precipitation and snow covering. In addition, harvest data are always influenced by man-but if proxy data or reconstructions match the historical descriptions, the probability of having correctly determined an extreme event is high.…”