Climate change is associated with phenological shifts in an increasing number of taxa worldwide. In particular plants growing in alpine regions and northern latitudes that traditionally have short growing seasons are shifting to earlier phenophase initiation. We compared the first flowering times of over 100 species of herbaceous plants in the Northern Red River Valley region of North Dakota and Minnesota in spring 2008 to first flowering times of the same species nearly a hundred years earlier based on archived data. We wanted to determine if plant flowering times had shifted earlier over the century. By merging climate variable data from the same time period it was also possible to correlate first flowering dates with climate variables for that specific year.

Results/Conclusions  

We found that first flowering times had shifted earlier than was previously recorded in a subset of the taxa we monitored. We were thus able to categorize species into responsive and non-responsive categories for flowering time. Analyses of correlations among climate variables and phenological shifts yielded insight into mechanisms initiating flowering and overall spring greenup in this plant community. We conclude that lengthening growing season in the Northern Red River Valley as a result of climate change has resulted in significant shifts in the timing of plant life cycles with potentially important ecological consequences.