Blossoms Blooming: Analyzing Plant Growth Patterns

• Use evidence to create an explanation.
• Analyze Behavior Over Time graphs of plant phenology data for Washington, D.C.’s Cherry Trees from 1921- 2018.
• Compare Peak Bloom graphs to near-surface temperature data collected in the same region and time.
• Infer relationships between plant phenology and climate change supported by evidence and reasoning.

1. How does the Biosphere respond to changing atmospheric temperatures?
2. How has the Biosphere changed since the early 1900’s through today?
3. What does plant phenology in the Washington D.C. area tell us about changing climates?
4. What effects do earlier phenology cycles in the calendar year have on other spheres in the Earth System?
5. How does NASA work with other organizations to help us better understand and interpret phenology data?

In the spring of 2018, the cherry trees around the Tidal Basin, southwest of the National Mall in Washington, D.C., reached Peak Bloom in early April 2018—timing that is in line with the 96-year average. After a warm February, cool March temperatures confounded models that had predicted the bloom to occur earlier than usual. That is not surprising, as temperature plays a crucial role in bloom timing. But over the longer term, climate change is causing spring to begin earlier and earlier across the United States. 

Maps reveal just how much earlier spring is arriving in National Parks across the country. The data were published in 2016 by ecologists from the National Park Service, working in collaboration with colleagues at other agencies and institutions. The first map shows the rate of change (days per century since 1901) of “First Leaf”—the date at which leaves first appear from buds. The second map shows the same rate of change for “First Bloom,” the average date when blooms appear. Combined, the two indices provide a way for ecologists to identify how vegetation is responding to warming temperatures.

“Climate changes are affecting resources across the entire range of National Parks,” said John Gross a climate change ecologist with the National Park Service. “Earlier springs, as indicated by leaf and flowering dates, is one of the most obvious and easily understood effects of climate change.” Of the 276 parks in the study (including Alaska, not pictured), about three-quarters of them are experiencing earlier springs. More than half are experiencing “extreme” early springs; that is, recent springs are among the earliest ever observed—and in many cases are wholly unprecedented—compared to the past 112 years. The charts below show that indeed, the vast majority of parks are experiencing First Leaf and First Bloom earlier than usual. This means that most parks are already experiencing and responding to climate-driven changes.

But as the maps also show, the magnitude of the change varies with location. Early blooming is evident in the swath of purple stretching from the south to the northeastern U.S. along the Appalachian Trail. Early leafing is quite evident in the southwestern part of the country, such as Grand Canyon National Park. Here, the long-term changes mean that spring is now arriving nearly two weeks earlier than it did in 1901. Still, other parks, such as Olympic National Park, are both blooming and leafing out earlier than normal. Conversely, some areas of the southeastern United States are not seeing much change at all; that region experienced less warming in the second half of the 20th Century.

Earlier springs have implications for how national parks are managed. The Cherry Blossom Festival in Washington, D.C., for example, has been lengthened to a multi-week event, making it more likely that the timing of the festival and Peak Bloom overlap. As the timing of spring has advanced, parks also have had to adjust the timing of management actions, which include hiring seasonal staff, opening park facilities, and initiating control of pests and invasive plants. According to Gross, park visitors are highly attuned to the beauty of the spring—from the emergence of buds to colorful flowers that emerge—and can observe for themselves how warming is changing the seasonality of parks. An earlier spring can affect the relationships between plants and pollinators, the wildlife that migrate in response to the greening of the plants they eat, and the return of birds that rely on the emergence of insects to feed their young.

“Changes in leaf and flowering dates have broad ramifications for nature,” Gross said. “Pollinators, migratory birds, hibernating species, elk, and caribou all rely on food sources that need to be available at the right time. Warming climates have disrupted these patterns, causing hardships for the animals and people that rely on them.”

NASA Earth Observatory images by Joshua Stevens, using data courtesy of
Monahan, William B., et al. (2016).
Story by Kathryn Hansen.

References and Related Reading

• EPA Climate Change Indicators (2016, April) Community Connection: Cherry Blossom Bloom Dates in Washington, D.C. Accessed April 5, 2018.
• Monahan, W.B. et al. (2016) Climate change is advancing spring onset across the U.S. national park system.Ecosphere, 7 (10).
• NASA Earth Observatory (2016, May 12) Natural Beauty at Risk: Preparing for Climate Change in National Parks.
• National Cherry Blossom Festival (2018, April) Bloom Watch 2018. Accessed April 5, 2018.
• The Washington Post (2018, March 20) Spring is springing earlier and earlier. Accessed April 5, 2018.
• Chung U, Mack L, Yun JI, Kim S-H (2011) Predicting the Timing of Cherry Blossoms in Washington, D.C. and Mid-Atlantic States in Response to Climate Change PLoS ONE 6(11): e27439.

Perhaps you are not interested in integrating the First Bloom of cherry blossoms into your instruction? Do not worry. Explore the phenology of native plants endemic to your area by using Budburst.

Budburst offers citizen science opportunities for students and teachers to better understand plant phenology in relation to environmental change for a wide variety of plants and locations.  Budburst contains many resources to integrate phenology observations including the ability to create student accounts and build a research site listing specific plants. Or, if you prefer to download and use phenological data today, you can query the database by plant, location, or date.

• Line Graphs
• Life cycle of plants
• Simple plant/environment interdependencies

• Scientists have already studied all the Earth’s systems so there will not be any new discoveries.
• Earth events taking place within the global environment are not interconnected,
• such as El Nino is not important to people living in the Midwest.
• The atmosphere, hydrosphere, lithosphere, and biosphere do not cause changes in
• one another; these systems operate independently on Earth.
• Increases in global temperatures in the atmosphere and the consequent warming of the oceans will only create a problem for people living along the coast.
• Earth has always been pretty much the way it is now.
• Life on Earth can not modify or cause changes in the Earth’s systems.
• Earth is too big for us to change, thus the impact of our activities is inconsequential.

 ~ Credit:  Center for School Reform at TERC’s MSPnet

In eastern North America, the spring “green up” phenomena is one of the most dramatic changes Earth-observing satellites record, indicating the time when leaves appear and begin growing. For more than three decades, NASA satellites have collected seasonal vegetation data and scientists are discovering interesting and consequential findings; the Northern Hemisphere growing season has lengthened over the past 30 years or so as the climate has warmed. The spring green-up arrives a week earlier in many Northern Hemisphere locations; however, not all important seasonal events can be observed with satellites. The most important event in the life cycle of flowering plants—flowering itself—is too small-scale and variable for satellites to observe directly.  Therefore, NASA scientists couple satellite data with the work from the broader research community featuring the Environmental Protection Agency and the National Park Service for validation purposes.

In this lesson, Blossoms Blooming: Analyzing Plant Growth Patterns, learners collect evidence from air temperatures and Peak Bloom data, to examine yearly variations in plant growth patterns from 1921 to 2018.  Students connect Behavior Over Time (BOT) graphs with data sets and review other resources to evaluate this changing phenomenon.

• Soil and Plant Scientists  - Explore the breeding, production, and management of crops, trees, and plants
• Atmospheric and Space Scientists - Investigate weather and climate-related phenomena to prepare weather reports and forecasts for the public
• Computer and Information Scientists - Conduct research in the field of computer and information science
• Remote Sensing Scientists and Technologists - Research a variety of topics using techniques that allow the study of an object or phenomena without making contact directly with the object such as analyzing geological and geographical data (They typically work with aerial or satellite pictures.)

To further your classroom’s inquiry with the phenological studies of cherry blossoms beyond Washington D.C., visit the Project Budburst’s Cherry Blossom Blitz courtesy of Chicago Botanic Gardens. Here, you can observe a local cherry tree with your students from February 15th through April 30th and report and report how the tree is changing.  The Cherry Blossom Blitz is a continental-scale campaign targeted to the collection of cherry blossom data by the public for research.

• Standalone Lesson (no technology required)
• Internet Required
• One-to-One (tablet, laptop, or CPU)
• One-to-a-Group