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Project BudBurst: Observing Plant Life Cycle Events to Track the Effects of Climate Change

On April 1, 2009, Kay Havens, PhD, strolled through the Chicago Botanic Garden (CBG), where she works as director of plant science and conservation. As Dr. Havens passed by the deciduous shrub forsythia (Forsythia x intermedia, Oleaceae), she noticed several bright yellow flowerspeeking out through the plant’s branches and leaves.

As these colorful blooms were appearing 2 weeks earlier than last year’s forsythia blooms in the Chicago area (and more than 3 weeks earlier than 2007’s blooms), Dr. Havens was a little surprised with these rather early signs of spring.1 Later, she reported her observation to the online national database for Project BudBurst, an organization for which she is lead botanist.

Created in 2007, Project BudBurst aims to use years of plant phenophase observations, just like Dr. Haven’s forsythia finding, in order to measure climate change and its effects on plants.2 Though some observers, like Dr. Havens, are scientists, the project is rooted in the participation of non-scientists, or citizen scientists, who monitor plants’ phenophases (the timing of life cycle events such as the first leafing, first flower, and first fruit ripening). A collaboration of CBG, the University Corporation for Atmospheric Research (UCAR), and University of Montana, the project is now in its second full year.

About 4,700 participants from all 50 states have been out and about in gardens and in nature observing plants (including many medicinal species) for the 2009 project, and about 1,400 of them just joined this year, said Kirsten Meymaris, lead technologist for Project BudBurst (e-mail, May 16, 2009). Participants begin to observe their plant about a week before the average budburst (when the buds have opened and leaves are visible), and upon noticing this life cycle change, they report their findings to the project’s online database.3 Throughout the growing season, participants continue to look for and report phenophase information. Since Project BudBurst’s creation, more than 7,500 observations have been amassed, including almost 5,000 from 2008’s project and 2,600 observations received in early 2009, said Meymaris.

The observations that Project BudBurst has collected so far provide valuable baseline data and make possible contemporary data comparisons, such as the finding that flowering dogwood (Cornus florida, Cornaceae) fully bloomed 2 weeks earlier in 2008 than it did in 2007.3 Additionally, the project might begin to accept historical datasets from participants in the future, said Dr. Havens. The observations are collected from a wide range of site conditions and geographical areas, making it possible to look at patterns of climate change across the whole country and in much greater detail than was possible in the past, said Paul Alaback, PhD, lead scientist of Project BudBurst (e-mail, May 21, 2009).

Both Dr. Havens and Dr. Alaback noted that in order to have enough information to document climate change trends, Project BudBurst will need many more years of data.

“Every year of data helps, but even after 2009, we’ll only have 2 full years of data and 3 months of observations from our pilot project in 2007,” said Dr. Havens. “It is still too early to say much about what is happening in any one location.”

As climate change can affect temperature, day length, and weather, it can in turn affect plants’ phenophases.4 Some plants are responding to climate change with earlier and/or longer growing seasons, and others are shifting their growing ranges toward the poles or higher elevations.3,5

“This is what we would expect as temperatures warm,” Dr. Havens said in a CBG press release.3 “Many people may welcome an earlier spring, but plants could be in trouble if they bloom before their pollinators are present.”

Many plants depend upon pollinators such as bees and other insects, or bats, for survival. While some pollinators will learn to adapt, many others breed and disperse based on sunlight cycles instead of temperatures and could have mismatched behavior with flowers that are blooming earlier.3 Also, pollinators who spend winters in the tropics don’t receive the same signals of spring temperature change and will need to evolve to migrate early, said Dr. Havens.

“Over time, natural selection will favor early migration, but we aren’t sure if this will happen fast enough to prevent species extinction or severe decline,” she said.

Species other than plants can also experience potentially damaging ecological consequences. For example, oak trees (Quercus spp., Fagaceae) in Europe are leafing earlier, and in response, the larvae of a moth that eats young oak leaves is hatching earlier, said Dr. Havens. “But the pied flycatcher that migrates back to Europe from more southerly wintering grounds has not altered its migration time,” she added. “By the time it arrives and nests, moth larvae are too old to feed to the flycatcher chicks and many chicks are starving as a result and the pied flycatcher is in decline.”

Project BudBurst introduced several new features this year, including photographic guides to the different phenophases of target species, a simple blog written by Dr. Havens and Dr. Alaback, and “real-time” Google maps that display the latest phenophase observations for each species.

To obtain an expanded geographical representation of plants, Project BudBurst increased the number of plants that it encourages participants to follow from 60 to 75, said Dr. Havens. Many of these targeted species have medicinal properties, including last year’s most observed plants: common lilac (Syringa vulgaris, Oleaceae),6 common dandelion (Taraxacum officinale, T. mongolicum, Asteraceae),7 forsythia (Forsythia suspensa, Oleaceae),8 flowering dogwood, 9 and red maple (Acer rubrum, Aceraceae).10 The citizen scientists can choose one or more plants from the list of 75, or they can follow any plant of their choosing.

These additions should make it easier for Project BudBurst participants, many of whom are school children, to correctly identify the phenological events of their plant, said Dr. Havens. Other features also help to ensure quality, such as a review of the dataset by scientists and comparison of the BudBurst dataset to observations collected by professionals.

“Public participation allows a much greater level of data collection—both in geographic span and number of observations—than could be done by scientists alone,” said Dr. Havens. “In addition, another goal of the project is to raise public awareness about climate change and its effects on plants.”

—Lindsay Stafford


  1. Monday, April 20, 2009: Spring is finally here... Project BudBurst Scientist Blog. Available at: Accessed May 21, 2009.

  2. About Us. Project BudBurst Web site. Available at: edu/citizen_science/budburst/aboutus.php. Accessed May 14, 2009.

  3. Citizen-scientists watch flowers for clues about climate: Chicago Botanic Garden’s Project BudBurst in second full year [press release]. Glencoe, IL; Chicago Botanic Garden. March 24, 2009.

  4. Phenology and Climate Change. Project BudBurst Web site. Available at: php. Accessed May 15, 2009.

  5. Cavaliere C. The effects of climate change on medicinal and aromatic plants. HerbalGram. 2009;81:44-57.

  6. Taxon: Taraxacum officinale F. H. Wigg. aggr. GRIN Database. Available at: Accessed May 18, 2009.

  7. Taxon: Syringa vulgaris L. GRIN Database. Available at: http://www.ars-grin. gov/cgi-bin/npgs/html/ Accessed May 18, 2009.

  8. Taxon: Cornus florida L. GRIN Database. Available at: http://www.ars-grin. gov/cgi-bin/npgs/html/ Accessed May 18, 2009.

  9. Taxon: Forsythia suspensa (Thunb.) Vahl. GRIN Database. Available at: http:// Accessed May 18, 2009.

  10. Taxon: Acer rubrum L. GRIN Database. Available at: http://www.ars-grin. gov/cgi-bin/npgs/html/ Accessed May 18, 2009.