Nature's Calendar - phenological observations made by Citizen Scientists: Plant's Calendar

Ola Langvall - Swedish University of Agricultural Sciences, Unit for Field-based Forest Research

Åslög Dahl - University of Gothenburg, Department of Biological & Environmental Sciences

Jacob Johansson - Lund University, Department of Biology

Kjell Bolmgren - Swedish University of Agricultural Sciences, Unit for Field-based Forest Research

Swedish Botanical Association

Swedish Beekeepers Association

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Nature's Calendar (www.naturenskalender.se, in Swedish only) is run by the Swedish National Phenology Network, a consortium of Swedish universities, governmental agencies and NGO:s. The Swedish University of Agricultural Sciences hosts the network. The main task for the Nature's calendar is to collect observations of different spring and autumn signs appearing during the vegetation season.

Data about the nature's calendar is collected in two ways, the long-term environmental monitoring through "Calendars", where phenological observations are reported all through the year, and through "Checks", where phenology observations are reported during short-time campaigns, giving a snapshot of the phenological status at a certain time of the year.

Calendars
The long-term environmental monitoring is performed by citizen scientists and professional observers at research stations and like. Three calendars have been launched in the Nature's Calendar; the Plant's Calendar (from 2008), the Bird's Calendar (from 2016) and the Beekeeper's Calendar (between 2015 and 2018).

Checks
Starting in 2015, a campaign called "Vårkollen" (i.e. "Spring Check") has been run during two (April 30 - May 1) or three (April 29 - May 1) days every year. The campaign, where the phenology of only 6 species (also available in the historical phenology dataset) gives a snapshot of how spring has proceeded all over the country at this time.

Aims
Phenological changes in nature gives the most obvious signs of the biological effect of climate change. Spring signs, autumn signs, the start, end and length of the growing season, and many other signs in nature are basic properties of ecosystems. Also, the interaction between different organisms, e.g. flowering plants and pollinators, are affected if the nature's calendar changes. Observations reported to the Nature's Calendar can be compared to similar observations collected for more than 100 years ago (see Swedish Historical Phenology Dataset, published in another place at this platform), to detect evidence of phenological shifts over time that can be connected to climate change.

The aim of the Nature's Calendar is to collect phenological data from the first spring sign to the last autumn sign, to be able to offer nation-wide data to everyone interested, to facilitate research, environmental assessments, the evaluation of environmental goals, etc, to be better prepared to meet the effects of climate change. For example, the data collected in Nature's Calendar is continuously used to evaluate the Swedish environmental objective Reduced Climate through the indicator called ”Growing Season” (www.slu.se/vaxternasvaxtsasong).

Three datasets are made available in this publication: the Plant's Calendar, the Beekeeper's Calendar and the Spring Check datasets. They all originate from the same database in the Nature's Calendar, while the Bird's Calendar observations are published through the Swedish Species Observation System Portal (www.artportalen.se).

In the Plant's Calendar, Citizen Scientist's have reported observations of how
- budburst and leaf development (broadleaves)
- budburst and shoot elongation (conifers)
- flowering
- ripening of fruits and berries
- seed dispersal
- autumn colors
- leaf shedding
develop during the growing season.

The aim with the data collection is to obtain nationwide data that can provide information to understand, track changes and predict effects of climate change on natural plants in Sweden.

The dataset includes one file with observation data (plants_calendar_2008-2021.csv), one file with the full species list used by the observers (plants_calendar_specieslist_2008-2021.csv), one file with the full list of phenological phases and sub-phases that observers can report (plants_calendar_phaselist_2008-2021.csv), one PDF file (metadata_plants_calendar_2008-2021.pdf) with metadata that describes how the above mentioned CSV files are related and how the included parameters should be interpreted, and one PDF file (vaxtkalendern_fenologimanual_2021.pdf) which describes the protocol used by those included in the phenology observer programme, i.e. the observations indicated as high quality (in Swedish, only). The observation data file includes totally 148 481 observations.

The data collection in the "Nature's Calendar - Plant's Calendar" started in 2008, but some observations made at a few locations at earlier dates have also been registered in the database, so this dataset includes a few records already from 1980 and forward.

Coordinates of the observation locations have been made diffuse, partly to make it impossible to trace back the observations to the observer (coordinates are rounded to 3 decimals), partly to make tracing back to the original location of protected species impossible (coordinates are rounded to 1.5 decimals = > 6 km diffusion), as to the rules for publicly handling of nationally protected species (see https://www.artdatabanken.se/var-verksamhet/fynddata/skyddsklassade-arter/). Show less..