Spring Temperature and Snow Cover Climatology Drive the Advanced Springtime Phenology (1991–2014) in the European Alps

Jing Xie,Fabia Hüsler,Michael E Schaepman,Yeran Sun,Barbara Chimani,Sarah Asam,Rogier De Jong,Mathias Kneubühler

doi:10.1029/2020jg006150

Abstract

AbstractShifts in phenology are important traces of climate change affecting mountainous ecosystems. We present an analysis of changes in spring phenology using a suite of Earth observation based parameters, that is, start of season (SOS), snow cover extent and meteorological variables from 1991 up to 2012/2014 for the European Alps. Our results show that SOS tends to occur earlier throughout the Alps during this period and spring temperatures have increased in the Eastern Alps. Spring temperatures presented a predominant influence on SOS for both, grasslands and forests across elevations between 500 and 2,200 m asl, while this effect is particularly pronounced in the northeastern Alps. Snow cover duration and snow cover melting days showed secondary impact on SOS. Our research provides a comprehensive observation of spatiotemporal changes in alpine spring vegetation phenology and its driving factors. They improve our understanding of the sensitivity of the European Alps ecosystems to a changing climate.

Highlights

The average global temperature has been reported rising in recent decades, in mountainous regions (IPCC, 2018, 2018)
All the average inter-annual trend values shown in Figure 2 are significant, and a high number of pixels [% of total] reflects that a significant regression was found on a high proportion of the natural vegetation (NV) areas
The negative trends of both SOSEVI2 and SOSNDVI are more pronounced in northern regions than in southern ones

Summary

Introduction

The average global temperature has been reported rising in recent decades, in mountainous regions (IPCC, 2018, 2018). The European Alps were reported to be sensitive to inter-annual variations in climatic drivers such as temperature, precipitation, and solar radiation (Beniston et al, 2003; Gobiet et al, 2014), as well as, depending on elevation, snow cover extent and its depth (Jonas et al, 2008; Xie et al, 2017). In the European Alps, springtime phenology has been well investigated with practice and evidence over the past years (Asam et al, 2018; Cornelius et al, 2013; Fontana et al, 2008; Galvagno et al, 2013; Ide & Oguma, 2013; Oehri et al, 2017, 2020; Pellerin et al, 2012), reported findings are mostly focusing on smaller geographical scales or selected aspects in observation. There are no significant inter-annual trends observed on SOS and its parallel driving seasonal snow and spring meteorological

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