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Example campaign - Was spring 2012 as early as spring 2010?
Background and Justification
Spring 2010 was anomalously early in much of the eastern United States, and resulted in lilacs and other species leafing and flowering weeks ahead of schedule. When 2012 began showing signs of another early spring, we launched a campaign across the northeastern quadrant of the United States to capture observations of plant phenology. Our question was, "Will spring 2012 arrive as early as spring 2010?"
We invited registered Nature’s Notebook participants in a region encompassing St. Louis, Missouri to the northeastern tip of Maine (region bounded by 38-48 degrees N and 65-90 degrees W) to carefully track the phenology of nine species from March 30-May 18, 2012.
Target tree species included:
- American beech (Fagus grandifolia)
- black cherry (Prunus serotina)
- eastern redbud (Cercis canadensis)
- northern red oak (Quercus rubra)
- paper birch (Betula papyrifera)
- red maple (Acer rubrum)
- sugar maple (Acer saccharum)
- tuliptree (Liriodendron tulipifera)
- white oak (Quercus alba)
We identified registered Nature’s Notebook observers who either a) had submitted one or more observations on one or more of the target species or b) had registered one or more of the target species but had not yet submitted observations. We then sent a series of five emails, spaced approximately two weeks apart, to these two groups:
- March 30, 2012: We emailed invitations to the two populations announcing the special project and inviting participation:
- April 13, 2012: We sent a follow-up email reminding individuals of the project and inviting participation.
- April 20, 2012: We sent an email providing results on the data submitted to-date.
- May 4, 2012: We sent a second email providing additional results.
- May 18, 2012: We sent a final email thanking the participants for their involvement and providing final results.
- July 13, 2012: We sent both groups a final message that presents results of an analysis comparing first leaf of the nine species in 2009, 2010, 2011, and 2012.
Over the seven-week course of the CTA, we collected 10,072 records of the nine target species (an observation record is a Yes or No reported for a single phenophase for a single individual organism on a particular day):
- American beech – 477 records
- black cherry – 637 records
- eastern redbud – 479 records
- northern red oak – 639 records
- paper birch – 1,203 records
- red maple – 3,905 records
- sugar maple – 2,160 records
- tulip tree – 253 records
- white oak – 319 records
Over 1,700 observations were reported over the course of this campaign, a 126% increase over the observations submitted during this period (Jan 1 – May 31) and the same region for the nine target species in 2011 (an observation is a report of a suite of phenophases for an individual plant or animal on a given day and includes from 3 to 10 phenophase status records, depending on the species).
This campaign resulted in 310 newly registered individual trees of the nine target species, a 49% increase over the 208 individuals of the nine species registered in 2011. The number of new individuals registered for the nine target species was also significantly greater in 2012 than in 2011. Finally, the number of observers with one or more individuals of the target species was also significantly greater in 2012 than 2011.
Final Results: Spring 2012 was as early as spring 2010!
We compared the first date that observers reported “yes” to “leaves” for the 9 deciduous tree species under investigation. Then we compared those dates collected in 2012 to the first “yes” dates reported for the same species in 2011, 2010, and 2009.
When we pooled observations for all species together across the study region, we found that the first leaf dates reported in 2012 were, on average, just as early as in 2010. These dates were, on average, a week earlier than in 2009, and nearly 3 weeks earlier than in 2011.
Spring in two of the four years we have been collecting data on these species has arrived anomalously early, suggesting that very early springs might be occurring more frequently. Will this pattern continue into the future? Only time will tell… well, that and lots of observations of plant phenology!