Module 2 PROXIES - Phenology

Magnitude and frequency of extremes in reproductive phenology

Schleip C, Pauler Ankerst D, Böck A, Estrella N, Menzel A (2012) Comprehensive methodological analysis of long-term changes in phenological extremes in Germany Global Change Biology 18, 2349–2364 (doi: 10.1111/j.1365-2486.2012.02701.x)

There is a clear lack of knowledge on the magnitude and frequency of extremes in phenological data. We analyzed long-term records of 14 indicator phases across Germany by four alternative statistical models to derive probabilities of extreme early or late onset times for the phases: (1) Gaussian models, (2) semi-parametric quantile regression, (3) Generalized extreme value distributions (GEV), and (4) Generalized Pareto distributions (GPD). This study demonstrated that probabilities of extreme late phenological events decreased and those of extreme earlier events strongly increased, with summer and autumn phases revealing a more pronounced advancing pattern than spring phases. Return levels by EVT methods indicated that extreme early phenological events of up to 2 months depending on the season and species would occur every 20 years for spring, summer and autumn phases.

Phenological response to the extreme autumn 2011

Schuster C, Jakobi G, Kirchner M, Menzel A (2013) Frequency of inversions affects senescence phenology of Acer pseudoplatanus and Fagus sylvatica. Int J Biometeor, online, DOI 10.1007/s00484-013-0709-0.

In a two-year observational study in the Alpine region near Garmisch / Germany, we analyzed phenological observations of leaf coloring and leaf fall in relation to inversion situations, in particular the one which occurred in autumn 2011. These situations are characterized by cold-air pools in the valleys and higher air temperatures in middle elevations. The deciduous tree species Acer pseudoplatanus and Fagus sylvatica on altitudinal transects responded in their leaf phenology by a significant shortening of senescence duration in the valleys. However, Acer pseudoplatanus proved to be more sensitive to cold temperatures compared to Fagus sylvatica.