Nature's Calendar: Early Summer Check - phenological observations made by Citizen Scientists

Nature's Calendar (www.naturenskalender.se, in Swedish only) is run by the Swedish National Phenology Network (SWE-NPN), a consortium of Swedish universities, governmental agencies and non-governmental organisations. The Swedish University of Agricultural Sciences (SLU) hosts the network and is part of the university's program for environmental monitoring and assessment. The main task for the Nature's calendar is to collect observations of different spring and autumn signs appearing during the vegetation season. SWE-NPN is connected to the monitoring of the Swedish Environmental Objectives, mainly concerning the objective Reduced Climate Impact, but is also collaborating with networks in Europe (through the Pan-European Phenology database - PEP725) and internationally (through the International Society of Biometeorology). 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. The long-term environmental monitoring is performed by citizen scientists and professional observers at research stations and like. Since 2022, a campaign called "Försommarkollen" (i.e. "Early Summer Check") has also been run June 5-6 every year (the World Environment Day and the Swedish National Day, respectively). In the Early Summer Check, Citizen Scientist's have reported observations of how far the development of flowering of Bird Cherry, Rowan, Lilac, Little Bluebell, Daisy and Lily of the Valley have progressed. All species, except Little Bluebell, has also been reported in the historical dataset mentioned below. Little Bluebell was included, as it recently was elected to be the Swedish National Flower. The Early Summer Check campain is performed by two SWE-NPN partners, SLU and the Swedish Botanical Association (SBF), where SLU provides the technical platform and data analyses and SBF produce folders and by hosting regional contacts for the press. The results are made available to the public by press releases directly after the campain is finished. Aims 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. Observations reported to the Nature's Calendar can be compared to similar observations collected for more than 100 years ago (see the Swedish Historical Phenology Dataset in "Related Reseach Data"), to detect evidence of phenological shifts over time that can be connected to climate change. The aim with the data collection of the Early Summer Check is to obtain nationwide data that can provide information to understand, track changes and predict effects of climate change on natural plants in Sweden by studying the progress of some species all over the country at one and the same date every year, and compare the current progress with what have been seen in historical records of the same plants. The dataset includes one file with observation data (early_summer_check_2022-2024.csv), one PDF file (metadata_early_summer_check_2022-2024.pdf) with metadata that describes how the included parameters should be interpreted and lists of included species and phases, and one PDF file (forsommarkollen_folder_2024.pdf) which is the instruction given to the observers (in Swedish, only). The observation data file includes totally 13 933 observations.