Land surface phenology and greenness in Alpine grasslands driven by seasonal snow and meteorological factors

Jing Xie; Tobias Jonas; Christian Rixen; Rogier de Jong; Irene Garonna; Claudia Notarnicola; Sarah Asam; Michael E Schaepman; Mathias Kneubühler

doi:10.1016/j.scitotenv.2020.138380

Land surface phenology and greenness in Alpine grasslands driven by seasonal snow and meteorological factors

Sci Total Environ. 2020 Jul 10:725:138380. doi: 10.1016/j.scitotenv.2020.138380. Epub 2020 Apr 4.

Authors

Jing Xie¹, Tobias Jonas², Christian Rixen², Rogier de Jong³, Irene Garonna³, Claudia Notarnicola⁴, Sarah Asam⁵, Michael E Schaepman³, Mathias Kneubühler³

Affiliations

¹ Remote Sensing Laboratories, Department of Geography, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland. Electronic address: jing.xie@geo.uzh.ch.
² WSL Institute for Snow and Avalanche Research, SLF Davos, Flüelastr. 11, 7260 Davos Dorf, Switzerland.
³ Remote Sensing Laboratories, Department of Geography, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland.
⁴ Institute for Earth Observation, EURAC, Viale Druso 1, I-39100 Bolzano, Italy.
⁵ Institute for Earth Observation, EURAC, Viale Druso 1, I-39100 Bolzano, Italy; German Remote Sensing Data Center, Earth Observation Center, German Aerospace Center, 82234 Wessling, Germany.

PMID: 32298886
DOI: 10.1016/j.scitotenv.2020.138380

Abstract

Snow accumulation and melt have multiple impacts on Land Surface Phenology (LSP) and greenness in Alpine grasslands. Our understanding of these impacts and their interactions with meteorological factors are still limited. In this study, we investigate this topic by analyzing LSP dynamics together with potential drivers, using satellite imagery and other data sources. LSP (start and end of season) and greenness metrics were extracted from time series of vegetation and leaf area index. As explanatory variables we used snow accumulation, snow cover melt date and meteorological factors. We tested for inter-annual co-variation of LSP and greenness metrics with seasonal snow and meteorological metrics across elevations and for four sub-regions of natural grasslands in the Swiss Alps over the period 2003-2014. We found strong positive correlations of snow cover melt date and snow accumulation with the start of season, especially at higher elevation. Autumn temperature was found to be important at the end of season below 2000 m above sea level (m asl), while autumn precipitation was relevant above 2000 m asl, indicating climatic growth limiting factors to be elevation dependent. The effects of snow and meteorological factors on greenness revealed that this metric tends to be influenced by temperatures at high elevations, and by snow melt date at low elevations. Given the high sensitivity of alpine grassland ecosystems, these results suggest that alpine grasslands may be particularly affected by future changes in seasonal snow, to varying degree depending on elevation.

Keywords: Alpine grasslands; Land surface phenology; Meteorological drivers; Snow cover melt; Snow water equivalent; Swiss Alps.