Early-flowering woodland plants, such as wild garlic and sedge, now begin their flowering season an average of about a week earlier than they did 100 years ago. Analyzes of thousands of herbariums also show that earlier flowering times of wild plants are linked to global warming, the research team from the universities of Tübingen and Frankfurt writes in the journal “New Phytologist”. On average, flowering time was advanced by 3.6 days per degree Celsius.
Franziska Willems and Oliver Bossdorf of the Institute for Evolution and Ecology of the University of Tübingen and JF Niek Scheepens of the University of Frankfurt am Main used the data for a new geospatial modeling method. The team built flowering time models that included geographic information and compared them to models without spatial data.
According to Willems, the result was clear: “The annual rhythm of early flowering and the extent of change in response to climate change varies not only between different plant species, but also in different regions.” So far, such studies have often been conducted only geographically.
20 species studied
Overall, the changes were correlated with warmer spring temperatures. According to the study, the flowering period advanced by an average of 3.6 days for each degree Celsius of warming.
For this study, researchers examined more than 6,000 herbarium specimens from 20 early-flowering species from across Europe. From this they wanted to extract shifts in phenology, that is, seasonal rhythms of development. Biological processes that repeat annually, such as the beginning of plant flowering or the beginning of bird migration, are examined under the technical term phenology. (but)