Pamela Kittelson

Pamela Kittelson is a professor of biology at Gustavus. She writes: 

A colleague from the University of Montana and I conducted research and published an article on how climate is shifting flowering time to earlier dates in the northern Rockies. We measured first flowering date for 34 species across the same plots over a 14-year time span.

We asked if first flowering date (FFD) had changed over time, and how FFD was associated with temperature and precipitation. 26 of the 34 species (76%) flowered earlier (~8 days earlier over 14 years); trend strongly significant for 10 of the 34 in that they flowered ~22 days earlier. The trend also was strong for species that usually flower earliest in the spring. March temperatures and winter precipitation were strongly correlated with the trend; specifically when winter snow decreased and March temp increased, FFD advanced.

Most studies examine temp; ours also incorporated precipitation, which is a major limiting factor in the west.