Title
Responses of tree seedlings near the alpine treeline to delayed snowmelt and reduced sky exposure
Date Issued
25 December 2017
Access level
open access
Resource Type
journal article
Author(s)
Bader M.
Loranger H.
Zotz G.
University of Marburg, Deutschhausstrasse 10
Publisher(s)
MDPI AG
Abstract
Earlier snowmelt changes spring stress exposure and growing-season length, possibly causing shifts in plant species dominance. If such shifts involve trees, this may lead to changes in treeline position. We hypothesized that earlier snowmelt would negatively affect the performance of tree seedlings near the treeline due to higher spring stress levels, but less so if seedlings were protected from the main stress factors of night frosts and excess solar radiation. We exposed seedlings of five European treeline tree species: Larix decidua, Picea abies, Pinus cembra, Pinus uncinata, and Sorbus aucuparia to two snow-cover treatments (early and late melting, with about two weeks difference) combined with reduced sky exposure during the day (shading) or night (night warming), repeated in two years, at a site about 200 m below the regional treeline elevation. Physiological stress levels (as indicated by lower Fv/Fm) in the first weeks after emergence from snow were higher in early-emerging seedlings. As expected, shade reduced stress, but contrary to expectation, night warming did not. However, early- and late-emerging seedlings did not differ overall in their growth or survival, and the interaction with shading was inconsistent between years. Overall, shading had the strongest effect, decreasing stress levels and mortality (in the early-emerging seedlings only), but also growth. A two-week difference in snow-cover duration did not strongly affect the seedlings, although even smaller differences have been shown to affect productivity in alpine and arctic tundra vegetation. Still, snowmelt timing cannot be discarded as important for regeneration in subalpine conditions, because (1) it is likely more critical in very snow-rich or snow-poor mountains or landscape positions; and (2) it can change (sub)alpine vegetation phenology and productivity, thereby affecting plant interactions, an aspect that should be considered in future studies.
Volume
9
Issue
1
Language
English
OCDE Knowledge area
Ciencias de las plantas, Botánica Conservación de la Biodiversidad
Scopus EID
2-s2.0-85039761923
Source
Forests
Sponsor(s)
Acknowledgments: We thank Serge Aubert, former director of the Lautaret Alpine Botanical Garden and the research station Joseph Fourier, for allowing us to use the experimental garden and station facilities, and the gardener team for their support. We acknowledge Marc Müller for his pioneering work on the experimental setups. Thanks also to several field assistants, especially Carla Sardemann, Mathilde Vicente, Jasmin Baruck, Gesa Pries, Verena Schenk, and Eric Thurm, for their help in installing, maintaining, and monitoring the experiment, and to Marianne Schäfer for digitizing the last field data. The study was funded by the German Research Foundation (DFG, BA 3843/5-1&2).
Sources of information: Directorio de Producción Científica Scopus