by Carl Strang
Flowering phenology is connected to seasonal weather patterns. Springs that are relatively cold and late, like this year’s, delay plant growth. Median dates tend to converge as the season progresses, however, and that has been clear this year. Median first flower dates for Mayslake Forest Preserve in June were one day earlier than in 2009, 5.5 days later than in 2010. These compare to respective May values of 4 days later and 14 days later.
In May, insect species first appearances were 9 days later than in 2010, 5 days later than in 2009. Again there was a convergence with the advancement of the season, with medians for 2011 two days earlier than in 2010, 2 days later than in 2009.
Year to year differences that are dramatic in the spring tend to vanish by late summer.