Western Spring Beauty, Colorado (credit: Southwest Colorado Wildflowers)
Anyone with a garden with distinct seasons has observered the time when first blooms appear in spring bulbs, flowering shrubs, or fruit trees. Such environmentally controlled events were carefully observed in 150 years ago by Henry David Thoreau who collected flowering records in Concord, Massachusetts. His notes on plants 'first blooming' and other life-cycle events is now a part of ecology called phenology.
Plants are very sensitive to their environment so they represent good biological indicators of climate change from increasing temperatures or declining snow cover. A new study published in Global Change Biology shows just how sensitive they actually can be over a very short time frame, even only a few short years. The research was led by Dartmouth doctoral student Zachariah Gezon who studied the western spring beauty (Claytonia lanceolata), a common mountain wildflower. Spring Beauty is one of the earliest plants to emerge from under the snow after the spring thaw in the Rocky Mountains.
Using a clever experiemental design, Gezon showed how the bulbous plant would react to shifting dates of snow disappearance. The investigators cleared snow from designated test plots when there was still more than three feet remaining on surrounding areas outside the plots. In the cleared study areas, an early flowering response was triggered in the dormant bulbs similar to what would be expected if climate change had induced temperatures to melt the snow. The time of flowering within the test plots occurred earlier than occurred on the uncleared areas. On average over the three year study, Claytonia grown in the cleared plots bloomed 10 days earlier than the same plants in areas that remained snow covered. Besides the plant's phenology sensitivity to an earlier snow "melt" as observed in the simulated warmer mountain environment, the flowering occurred before any insect pollinators were available and so eliminated any seeds being produced.
An interesting video explains the ecological concept behind phenology and a national organization, the National Phenology Network exists where "citizen scientists" can contribute their own observations to help further this important science on the cutting edge of climate change.