In recent decades, the signs of spring across the country have come an average of twelve days earlier than 150 years ago. The researchers know this because there is data as far back as 1873.
For ten years, the public has been invited to participate in Vårkollen. On Walborg and 1 May, people all over Sweden go out into the woods and fields to see how far six different species have come.
– We want data on tussilago, blue sedge, white sedge, willow, hemlock and birch. There are usually between three and five thousand people who participate, says Mora Aronsson, chairman of the Swedish Botanical Association.
Mismatch between pollinators and plants
The data is reported to Sweden’s University of Agricultural Sciences and they use the information to, among other things, make climate models for the climate of the future.
– This can be beneficial for farmers and fruit growers, for example. With a warmer climate, you need to know how to plan the growing season.
A longer growing season has its advantages, but also creates problems.
– One problem we get when the seasons shift is that there is a mismatch between pollinators and plants; that the insects are not in place when the plants flower.
Come along to Hjälstaviken in Uppland in the clip above to see how far spring has come there this year. And how it was 150 years ago.