DOI: 10.16904/envidat.635
title: IMIS Phenology Data Since 1998

description: Long-term phenological data in alpine regions are often limited to a few locations and thus, little is known about climate-change induced plant phenological shifts above the treeline. Because plant growth initiation in seasonally snow-covered regions is largely driven by snowmelt timing and local temperature, it is essential to simultaneously track phenological shifts, snowmelt, and near-ground temperatures. In this study, we make use of ultrasonic snow height sensors installed at climate stations in the Swiss Alps to reveal phenological advance of grassland ecosystems and relate them to climatic changes over 25 years (1998 – 2023). When snow is absent, these snow height sensors additionally provide information on plant growth at a uniquely fine temporal scale. Daily temperatures and snow- / plant height values, annual phenological- and melt-out dates were derived from IMIS climate station data (doi.org/10.16904/envidat.406). We observed an advance of green-up by -2.4 days/decade coinciding with strong warming of up to +0.8°C/decade. Although the timing of melt-out has not changed significantly over the study period in this focal region, phenological responses to early melt-out years varied due to differing influences of photoperiodic and thermal constraints, which were not equally important across elevations and communities. Phenological shifts of alpine grasslands are thus likely to become even more pronounced if melt-out timing advances in the future as predicted. 
This repository relates to the publication Zehnder et al. (2025). Snow height sensors reveal phenological advance in alpine grasslands. Global Change Biology. accepted. The model data and code that support our findings are deposited in this repository.
description: Resource Title: all_stations.csv
 Size: 1351408 bytes
 Format: application/vnd.ms-excel
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/2f390316-91a2-4600-a188-b6c1045065c1/download/all_stations.csv
 Description: Contains unfiltered annual phenological, temperature and snow-climatic data for all IMIS stations.
description: Resource Title: IMIS_daily.csv
 Size: 198550707 bytes
 Format: application/vnd.ms-excel
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/4d2df843-22cf-46a4-84bb-a5eb09e6d1e0/download/imis_daily.csv
 Description: Contains daily climate station data including daily median temperatures, snow depth, plant height, and annual melt-out timings.
description: Resource Title: pheno_params.csv
 Size: 417970 bytes
 Format: application/vnd.ms-excel
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/1a1b4c9a-2fe8-471f-8c36-616d5fd17738/download/pheno_params.csv
 Description: Contains annual phenological variables and phenofit outputs, sorted, ordered and renamed according with the readme in this repository
description: Resource Title: phenofit_outputlist.rds
 Size: 132907 bytes
 Format: application/octet-stream
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/95fca3e1-8f8f-4b1b-bc53-9c9778462b67/download/phenofit_outputlist.rds
 Description: Temporary data. Contains annual unfiltered output of phenofit (i.e. the variable names are in line with the phenofit documentation), including all curve parametrization variables for plotting and additional variables, which are not necessarily used in the analysis.
description: Resource Title: phenostations.csv
 Size: 463262 bytes
 Format: application/vnd.ms-excel
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/210f372a-6bf4-42ce-aadc-6751e00c2a74/download/phenostations.csv
 Description: Contains filtered annual phenological data from 40 IMIS stations suitable and used for phenological analysis
description: Resource Title: station_info.csv
 Size: 14695 bytes
 Format: application/vnd.ms-excel
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/1e867868-1e64-4ec6-9788-aaa7ab9fd561/download/station_info.csv
 Description: Contains IMIS station location data
description: Resource Title: 0_readme.Rmd
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 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/89105a24-c1b0-457f-8ad4-deb0a91e2aee/download/0_readme.rmd
 Description: Is the readme that documents all data and code in this repository
description: Resource Title: 1_phenofit.R
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 Format: application/octet-stream
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/08e70804-eed7-4a7c-8ad8-1a28c85deb2d/download/1_phenofit.r
 Description: implements the phenofit method. Note: This script is computationally intensive and may take a while to run. We recommend using the temporary data created from it (i.e. starting from 2_temperature.R). For a better description of the phenofit R package and the different methods to determine the SOG, see Kong et al. (2022): https://doi.org/10.1111/2041-210X.13870
description: Resource Title: 2_temperature.R
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 Format: application/octet-stream
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/19951a82-e3bf-4650-bc36-dbe502dff703/download/2_temperature.r
 Description: Contains temperature-related calculations.
description: Resource Title: 3_models.Rmd
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 Description: Documents and reproduces the statistical models used in the analysis.
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 Description: Contains custom functions required for the scripts; this file must be sourced before running other scripts.
description: Resource Title: 5_method_plots.Rmd
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 Description: Generates the methods-related figures used in the publication.
description: Resource Title: grass.png
 Size: 30676 bytes
 Format: image/png
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/c190e750-7951-4434-b3e1-325bca7a6ddc/download/grass.png
 Description: Snow3.png and grass.png are needed for plotting the methods plot in 5_methods_plots.Rmd
description: Resource Title: snow3.png
 Size: 12808 bytes
 Format: image/png
 URL: https://www.envidat.ch/dataset/53a457eb-0915-43d1-98ec-a11b4963b6ff/resource/afa71796-2a2e-4b7b-9885-d2a0fa47ed31/download/snow3.png
 Description: Snow3.png and grass.png are needed for plotting the methods plot in 5_methods_plots.Rmd