Monday, April 19, 2010

Is spring advancing in Chicago?

Spring has fully arrived in the Chicago region. With the last 2 days in the mid-80s, it almost felt like summer, but we’re cooling off to more spring-like temperatures this weekend. We had our first 80 degree day on April 1 and that unseasonably early warmth popped open a lot of flowers. Forsythia (Forsythia x intermedia) opened its first flowers that day, the same date as a year ago. Forsythia has proven to be one of the biggest “advancers,” a species that is blooming earlier in the year. In just the three years of records from Project BudBurst, we’ve seen significantly earlier blooming of Forsythia in the Chicago area.

This year I was able to compare Project BudBurst data collected in the Chicago region to some historical observations by the preeminent Chicago botanists Floyd Swink and Gerry Wilhelm published in their Plants of the Chicago Region (1994). Swink and Wilhelm made phenology observations from the mid 1950s to the early 1990s for their book. There were 15 species that had both Project BudBurst observations and historical data. Seven of those species had a first flower earlier in one or more of the last 3 years than even seen by Swink and Wilhelm. These species included Forsythia which advanced the most (from April 25, the earliest historical observation, to April 1, the earliest Project BudBurst observation), Spiderwort (Tradescantia ohiensis) advanced from May 14 to May 3, Dogtooth violet (Erythronium americanum) advanced from April 6 to April 1, Red Maple (Acer rubrum) advanced from March 20 to March 6, Mayapple (Podophyllum peltatum) advanced from May 1 to April 26, Black locust (Robinia pseudoacacia) advanced from May 9 to April 20, and Common lilac (Syringa vulgaris) advanced from May 3 to April 16. This year, we can document an even earlier lilac bloom. I saw the first flower open just two days ago (April 14) at Chicago Botanic Garden.

Many thanks to all of you who are watching plants and submitting your observations! Getting out to a natural area and admiring the spring wildflowers is a wonderful way to celebrate Earth Day (April 22). I hope you have a chance to do so, and let us know what you see!

Kay Havens

1 comment:

  1. That's pretty amazing that these plants are coming out 2-3 weeks earlier! Will be interesting to see if they keep coming out earlier at the same rate with new budburst observations. we are seeing really rapid advances in spring in semi arid western areas too