title: Small-scale drivers: the importance of nutrient availability and snowmelt timing on performance of the alpine shrub Salix herbacea.
abstract: Alpine plant communities are predicted to face range shifts and possibly extinctions with climate change. Fine-scale environmental variation such as nutrient availability or snowmelt timing may contribute to the ability of plant species to persist locally; however, variation in nutrient availability in alpine landscapes is largely unmeasured. On three mountains around Davos, Switzerland, we deployed Plant Root Simulator probes around 58 Salix herbacea plants along an elevational and microhabitat gradient to measure nutrient availability during the first 5 weeks of the summer growing season, and used in situ temperature loggers and observational data to determine date of spring snowmelt. We also visited the plants weekly to assess performance, as measured by stem number, fruiting, and herbivory damage. We found a wide snowmelt gradient which determined growing season length, as well as variations of an order of magnitude or more in the accumulation of 12 nutrients between different microhabitats. Higher nutrient availability had negative effects on most shrub performance metrics, for instance decreasing stem number and the proportion of stems producing fruits. High nutrient availability was associated with increased herbivory damage in early-melting microhabitats, but among late-emerging plants this pattern was reversed. We demonstrate that nutrient availability is highly variable in alpine settings, and that it strongly influences performance in an alpine dwarf shrub, sometimes modifying the response of shrubs to snowmelt timing. As the climate warms and human-induced nitrogen deposition continues in the Alps, these factors may contribute to patterns of local plants persistence.
authors.affiliation: WSL Institute for Snow and Avalanche Research SLF, 7260, Davos, Switzerland. Chelsea.jean.little@gmail.com.|Department of Aquatic Ecology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland. Chelsea.jean.little@gmail.com.
authors.forename: Chelsea J
authors.identifier: http://orcid.org/0000-0003-2803-7465
authors.initials: CJ
authors.lastname: Little
authors.affiliation: WSL Institute for Snow and Avalanche Research SLF, 7260, Davos, Switzerland.|Institute of Botany, University of Basel, 4056, Basel, Switzerland.
authors.forename: Julia A
authors.initials: JA
authors.lastname: Wheeler
authors.affiliation: Department of Biology, University of Konstanz, 78457, Constance, Germany.
authors.forename: Janosch
authors.initials: J
authors.lastname: Sedlacek
authors.affiliation: Department of Ecology and Genetics, Uppsala University, 75236, Uppsala, Sweden.
authors.forename: Andrés J
authors.initials: AJ
authors.lastname: Cortés
authors.affiliation: WSL Institute for Snow and Avalanche Research SLF, 7260, Davos, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Rixen
mesh_terms: D057231:Climate Change; D017753:Ecosystem; D009584:Nitrogen / Q000032:analysis* / Q000378:metabolism; D025341:Principal Component Analysis; D012098:Reproduction / Q000502:physiology; D032108:Salix / Q000254:growth & development / Q000502:physiology*; D012621:Seasons; D012914:Snow; D013557:Switzerland; D013997:Time Factors
chemical_list: D009584:Nitrogen
keywords: Global change; Herbivory; Microhabitat; Reproduction; Spring warming