American Scientist

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American Scientist

the magazine of Sigma Xi, The Scientific Research Society

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 Feature Article

Citizen Science Takes Root Building on a long tradition, amateur naturalists are gathering data for understanding both seasonal events and the effects of climate change.

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n the mid-1800s, Henry David Thoreau sojourned outside Concord, Massachusetts, immersing himself in the world around him. He planted beans, entertained visitors, repaired to his mother’s house in Concord for hearty meals, and wrote Walden; or, Life in the Woods. Less widely read are the copious observations and measurements he made around the same time, between 1851 and 1858, of plants and animals at Walden Pond. But more than a century later, his records are drawing attention in their own right among ecologists seeking a view into past climates. Thoreau was especially interested in the initial leafing and flowering of plants in springtime. He made notes on more than 500 plant species during his time at Walden. His observations contain valuable reference points for judging how those species have responded to changes in their environment, including changes in temperature and precipitation, over periods for which there would otherwise be little data. Thoreau thus might be considered an early practitioner of what we now call citizen science. The field, which was given its name in the 1990s by researchers at the Cornell Laboratory of Ornithology, empowers people from all walks of

Kayri Havens is the Medard and Elizabeth Welch Director of Plant Science and Conservation and Senior Scientist at the Chicago Botanic Garden. Her research interests include the effects of climate change on plant species, restoration genetics, and, of course, phenology. Sandra Henderson is the Director of Citizen Science at the National Ecological Observatory Network (NEON) in Boulder, Colorado. She was recently honored as a White House Citizen Science Champion of Change. Address for Havens: Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, IL, 60022. E-mail: [email protected] 378

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life to participate in the scientific process and help advance knowledge in a wide range of scientific disciplines. Thanks in part to the ease of collaborating with partners and reporting results via the Internet, such projects have proliferated over the past decade, collecting tens to hundreds of thousands of observations and working at continental and even global scales. Their benefits are educational and also scientific: Many studies have found that when reasonable quality control methods are used, the data

large data sets collected over long timescales, it can be hard to see clearly the effects of gradual changes in temperature, rainfall, and other factors. If the data cover only a short period, an anomalous year can have a large effect on observed trends. Project BudBurst takes a crowdsourcing approach to this problem. In the six years since the project began, participants have contributed tens of thousands of observations on hundreds of plant species—and the number of

When the oak leaves are the size of a mouse’s ear (or a squirrel’s ear), it’s time to plant the corn (or look for morels). —folk saying, North America citizen scientists collect are of publishable quality. The scientific community is beginning to recognize citizen scientist partners as important collaborators, even as ambassadors for science. Project BudBurst, a large-scale project we have codirected since its inception in 2007, is demonstrating the results such work can have for science education and data collection. In the spirit of Thoreau and other early observers of plant life, the project engages people across the United States in a collaborative effort to gather data on plant life cycles. In the process, participants are broadening their own scientific knowledge—and helping ecologists discover how plants respond to environmental change. The Science of Appearance Tracking species’ responses to climate change is notoriously tricky. Without

participants continues to climb. Plants’ life cycles are an attractive subject of study for citizen science because they are relatively easy to discern. In fact, the name for the field in which we work, phenology, literally means “the science of appearance.” The word was coined just a few years after Thoreau made his phenological observations, from the Greek phaino (to show or appear) and logos (to study). Phenology measures During his time at Walden Pond, near Concord, Massachusetts, Henry David Thoreau (1817–1862) (facing page, upper left) recorded observations on the timing of events in plants’ and animals’ life cycles. Shown at far right is the spyglass with which he observed birds. He also collected plant specimens, such as twigrush (Cladium mariscoides, near right) and switchgrass (Panicum virgatum), sometimes noting common names and the locations and life stages in which the plants were found.

© 2013 Sigma Xi, The Scientific Research Society. Reproduction with permission only. Contact [email protected].

Rare Book Collection, Wilson Library, The University of North Carolina at Chapel Hill/George Stafford Torrey Herbarium at UConn/Concord Museum, photograph by David Bohl

Kayri Havens and Sandra Henderson

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life cycle events, or phenophases, in all living things. Plant phenophases are associated with leafing, flowering, and fruiting: first leaf, first flower and last flower, among others (see the illustration on the facing page). Bud burst, the phenophase from which Project BudBurst

terns of weather, climate, and resource availability. Phenological studies are thus a simple and cost-effective way to measure changes in the climate over the long term. They can help in efforts aimed at improving quality of life and economic health—for instance, they are

When shadbush (Amelanchier species) blooms, shad are running in the Connecticut River. —folk saying, eastern United States takes its name, refers to the first opening of leaf buds in spring. The timing of phenological events can be very sensitive to environmental conditions. In a particularly warm spring, bud burst and first flower may occur weeks earlier than usual, whereas in a very cool spring they may be delayed. Such timing tends to vary from year to year in accordance with pat-

used in maximizing crop production, predicting pollen levels in order to improve seasonal allergy warnings, and anticipating optimal wildflower viewing and fall color conditions. More crucially, these studies help ecologists track the effects of climate change on organisms to make predictions about how the species will respondin the future. Of particular in-

terest is the possibility of phenological mismatches. Plants and other organisms have coevolved and are part of intricate relations, or mutualisms, with insects, birds, and other animals that serve as pollinators and seed dispersers. Some plants and their mutualists— organisms with which they interact in order to improve their ability to survive and reproduce—rely on different cues for first emergence and other phenophases. For instance, one species may rely on temperature, the other on day length. In such cases, it is possible that climatic change will disrupt these mutualisms, which may in turn cause some species’ populations to decline. Human interest in phenology is much older than anthropogenic climate change, however, and certainly older than the citizen science movement. The roots of citizen science can be traced to 1900, perhaps, when the Audubon Society began its Christmas bird counts, or to the late 1800s, when the fledgling National Weather Service culled information from amateur meteorologists (see the timeline below). But the first known phenological records were made by

Citizen Science Past and Present In a sense, all scientists were once citizen scientists. The distinction between the two became truly meaningful only after the professionalization of Western science in

the 19th century. Here we highlight some notable contributions from people who worked outside of what we would regard today as the formal academic world.

ca. 900 BCE In Japan, people begin recording the blooming dates of sakura (Prunus serrulata) trees, whose peak blossoming is celebrated each year.

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British landowner Robert Marsham publishes Indications of Spring, his decades-long observations of plants and animals on his estate.

The U.S. National Weather Service begins to make forecasts, using instruments such as rain gauges (left) along with observations from amateur meteorologists.

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Henry David Thoreau begins his observations of plant and animal life cycles at Walden Pond, near Concord, Massachusetts.

Ornithologist Frank Chapman organizes the first Audubon Christmas bird count, with 27 birders in the United States and Canada observing 90 total species. The count, begun as an alternative to Christmas “side hunts” in which large numbers of animals were killed, has been repeated each year since 1900.


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Albany Institute of History & Art/archival photograph Sean Linehan, NOS, NGS/Concord Museum, photograph by David Bohl


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the Chinese in 974 bce. And beginning around the 9th century ce, observations of the timing of peak cherry blossoms in Japan have been recorded. In Europe, such record-keeping began more recently: In the mid-1700s, the Swedish botanist Carolus Linnaeus systematically noted flowering times for 18 locations in Sweden over many years. He shares the honor of being considered a founder of modern plant phenology with 18th-century British landowner Robert Marsham. Beginning in 1736, Marsham recorded the date of first occurrence of events such as plant flowering and insect emergence on his estate. For generations, Marsham’s family maintained their records, which ended with the death of Mary Marsham in 1958. Ecologists have worked recently to extend historical records into the present. Several studies have compared Thoreau’s notes on plant species to observations of species found at Walden Pond today. Abe Miller-Rushing and Richard Primack of Boston University collected observations on hundreds of plant species that Thoreau had carefully tracked. Comparisons between the historical and modern data revealed profound changes in plant phenology. The timing of spring phenophases at Walden has advanced by an average of one week for many species. These data

bare branches

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flowers half fall color

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U.S. illustrator and naturalist Anna Botsford Comstock publishes A Handbook of Nature Study, amid a wave of interest in incorporating observation of the natural world into elementary education.

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ripe fruit

Phenology, literally “the science of appearance,” is the study of the timing of events in organisms’ life cycles, known as phenophases. Shown here are significant seasonal phenophases for an apple tree (Malus domestica), from first leaves in spring to bare branches in winter. Climate change and other environmental changes can affect the timing of plant and animal phenophases, with potential consequences for species that respond to different seasonal cues but that depend on each other for pollination, food, and other needs. (Adapted from an illustration by NEON.)

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2007 Project BudBurst is launched, with 917 participants signing up in its initial 10-week pilot program.

Aldo Leopold begins recording natural-history observations at his farm in central Wisconsin, and does so through 1948. Nina Leopold Bradley carries on her father’s work from 1976 until her death in 2011. Today visitors to the farm are invited to share their observations.

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The Southern African Birds Atlas Project begins at the University of Cape Town, relying on observations from thousands of citizens. The project publishes the resulting atlas in 1992; similar, larger projects continue to the present.

The phrase “citizen science” is coined by researchers at the Cornell Laboratory of Ornithology in Ithaca, N.Y.

Scientists at Boston University begin collecting observations to compare with Thoreau’s historical records, inspiring citizen scientists in the Concord, Massachussetts, region to submit their observations on bloom time.

Galaxy Zoo, an online project that allows anyone to help classify photographs of galaxies, is founded.

Hundreds of citizen science projects are ongoing around the world, with millions of people participating.

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in the environmental sciences. They provide something that human-made instruments do not: integrative measures of organisms’ physical, chemical, and biological environments. In addition, gathering these data offers people both the opportunity for hands-on learning and an excuse to spend time outdoors.

When maples flower and woodchucks dig up the hillsides, ducks are scouting for nesting sites, and onion sets can be tucked into the garden soil. —folk saying, midwestern United States track phenology, known as remote sensing phenology, can detect broad-scale events, such as the onset of spring— called green-up—and of autumn, or brown-down, when the leaves fall and the grasses turn brown. Many phenologists also use automatic cameras to assess changes in areas that are difficult to access regularly. Observations made at the human scale remain an essential component of phenological monitoring, however. Such records are a valuable asset

A Nation of Flower Watchers In the early 2000s, ecologists and other scientists felt the need for a comprehensive plant-monitoring project to understand the effects of climate change— one that could efficiently collect numerous observations from a wide geographic range. At the same time, popular interest in plant phenology was growing, inspired in part by people’s increasing awareness of climate change and its potential effects. The time was right for Project BudBurst. In October 2006, the National Science Foundation funded a meeting at the University of Wisconsin– Milwaukee to address the need for a national phenology network. A small working group, of which we were a part, created a draft plan for a project that would enlist the help of the general public in monitoring plants across the United States. Our goals were twofold: first, to aid science education and, second, to advance scientific knowledge. The project would be simple Participants in Project BudBurst, a U.S. citizen science project, observe plants’ life cycle events. Above, Becky Barak and Paul and open to all, with a central database, Hartzog of the Chicago Botanic Garden test the project’s mobile straightforward prointerface by reporting results for tall coreopsis (Coreopsis tripteris). tocols, and all nec(Photograph courtesy of the Chicago Botanic Garden.) 382


essary materials and resources available online. Shortly after the meeting, we began to develop a pilot version, supported by modest funding from the U.S. Bureau of Land Management, through the Chicago Botanic Garden. Carol Brewer, then associate dean at the University of Montana (now emeritus), worked with us to help make the project ready for its spring 2007 launch. Response to the program greatly exceeded our expectations. It attracted a diverse group of participants from all across the country, as well as widespread attention from blogs, newspapers, and television and radio programs. We were already making progress toward our goal of improvingpublic understanding and awareness of phenology. Inclusivity and ease of participation likely helped in our early success. To participate, volunteers choose a plant, observe it, and report a variety of data about it, noting the timing of phenophases such as first flower, first fruit, and all leaves withered. We ask for the plant’s common name and scientific name as well as details about the habitat in which it is growing: amount of shade, amount of irrigation, and distance to human development. The unique location is tracked via a participant-chosen site name, latitude and longitude, and city and state. Volunteers can submit data via regular reports, in which they observe a plant throughout the seasons and note the timing of phenophases, and single reports, in which they send a one-time observation of a plant’s status on a given day. To help participants identify and choose plants to monitor, we created a master plant list that highlights more than 250 species, selected for their wide geographic distribution, ease of identification, and scientific interest. Our website offers a resource page for each species, which includes an identification guide, data sheets for observations, a live map, and a data viewer. There is no cost to participate, and the reporting interface is simple enough that, with assistance, even elementary school–age children can help out. We also made a 10-most-wanted plant list, which encourages observations that will help build a more comprehensive data set for these target species. Early on, however, we received many observations of species not on our lists, so we decided to support reports on any plant in order to keep participation as inclusive as possible.


Wikimedia Commons

provide support for a novel hypothesis: Species that can quickly change such timing in response to changes in climate tend to be more common today than those whose timing has not changed significantly since Thoreau’s day. Contemporary phenologists have the benefit of new technologies. The use of data from satellites and airplanes to

Julian day of first flower

Stillwater, Minnesota

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Silver Spring, Maryland Julian day of first flower

Golden, Colorado

Julian day of first flower

Syringa vulgaris

Common lilac (Syringa vulgaris) thrives in a wide variety of locations and can thus be used to make comparisons across geographic regions. Project BudBurst is beginning to track this and other species’ responses to climate change. Shown at right are changes in the date of first bloom for the species in three locations. To avoid inconsistencies caused by leap years, the dates used are Julian rather than the usual Gregorian.

With feedback from participants, along with funding from a variety of sources, we have made the BudBurst website and supporting resources much more comprehensive over the past six years. We have created campaigns— Cherry Blossom Blitz, Summer Solstice Snapshot, and Fall into Phenology— that promote the project and highlight seasonal phenophases. A new project, the Floral Report Card, has created gardens of identical species in 10 sites around the country, with the goal of monitoring plants across a wide geographic and climatic range. This past summer our team developed a mobilefriendly version of the project website to make things even easier; now participants can report field observations from their smartphones or tablets. We have also developed online courses to support educators who want to use Project BudBurst in their classrooms. In less than a year, more than 400 educators have enrolled in these self-paced courses. In 2014, we plan to launch a curriculum series for grades 5–12, Climate Change in My Backyard, that uses Project BudBurst participation and NASA climate data to teach about climate change and its effects on the environment. www.americanscientist.org

It can be a challenge to measure the achievement of broad educational goals, but we find encouragement in several sources. A Google search for Project BudBurst in mid-2013 returned close to 23,000 entries. The project has been covered in more than 300 articles and interviews. And since the beginning, that high level of interest has made it easy to recruit volunteers: To date we have more than 15,500 registered participants making regular contributions. Project BudBurst has thrived on a partnership model in our educational and scientific efforts. We work with agencies such as the U.S. Fish and Wildlife Refuge System, the U.S. National Park System, science centers, and natural history museums to identify plants of unique local interest. Data gathered by the project are freely available for scientists and citizens to use. The result is a robust nationwide citizen science program—one in which anyone can step into Thoreau’s or Marsham’s shoes. Educational Science Project BudBurst’s goals of aiding science education and advancing scientific knowledge are mutually supportive: Volunteers gain satisfaction from the knowledge that their observations are

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contributing to the project, and scientific publications that use project data can feed interest (and help in fundraising). BudBurst data have been used in several scientific papers, including one by Uran Chung and her colleagues, who modeled the timing of cherry-blossom peak bloom for trees in the Washington, DC, region under various scenarios of climate change. The ecologists found that under the Intergovernmental Panel on Climate Change’s A2, or high, emissions scenario, the trees may bloom 29 days earlier by 2080. The results have also been used in several regional historical studies. For example, in 2012 we compared Project BudBurst data collected in the Chicago region with observations published by botanists Floyd Swink and Gerry Wilhelm in their 1994 book Plants of the Chicago Region. Swink and Wilhelm collected phenology observations from the mid-1950s to the early 1990s. Of the 15 local species for which we had good contemporary and historical data, 13 had an earlier first flower in one or more years between 2007 and 2012 than was ever observed by Swink and Wilhelm. Data on these timescales thus begin to reveal the effects of climate change on plants.


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In another study, Elizabeth Wolkovich, of the National Center for Ecological Analysis and Synthesis, and Elsa Cleland, of the University of California–San Diego, asked whether the success of invasive introduced species was due, at least in part, to a “seasonal priority” effect. If a nonnative plant species leafs out earlier than native species, it may be able to exploit resources first and shade out its competitors. The authors’ analysis of Project BudBurst data revealed that introduced species leafed out on average 3.74 days earlier than their native neighbors, suggesting that climate change is accelerating the threat of these species. In 2012 we also plotted trends in first flowering date from Project BudBurst data (see the illustration on page 383 for one example). We found a trend toward earlier flowering in all of the graphs we made—likely due in part to the extraordinarily early spring we saw in much of the country in 2012. With data sets collected over relatively short time scales, an anomalous year can have a large effect on the observed trend. As we gather data over longer and longer periods, such effects diminish, and the ecological effects of climate change grow more distinct. Over time, BudBurst participants will be able to see more and more clearly that their individual observations have global importance.

Oak before ash, in for a splash; ash before oak, in for a soak.

Lessons for Scientists Successful citizen science projects work to create connections between the intimate stories that unique observations tell and the bigger story of the project data set. These programs, such as Project FeederWatch, Monarch Watch, and CoCoRaHS (a network that measures precipitation), take advan384


—folk saying, Great Britain

Project BudBurst encourages reports for plants on its 10-most-wanted list: clockwise from upper left, California poppy (Eschscholzia californica), red maple (Acer rubrum), red osier dogwood (Cornus sericea), forsythia (Forsythia x intermedia), common lilac (Syringa vulgaris), southern magnolia (Magnolia grandiflora), chokecherry (Prunus virginiana), Virginia bluebells (Mertensia virginica), mayapple (Podophyllum peltatum), and red columbine (Aquilegia canadensis). (Photographs from the USDA Plants Database/Wikimedia Commons.) © 2013 Sigma Xi, The Scientific Research Society. Reproduction with permission only. Contact [email protected].

tage of activities that people like to do already, such as birding, gardening, or taking nature walks, and allow participants to share and archive their observations as well as contribute to scientific studies. Project BudBurst is fortunate to be part of a worldwide trend: Work by several researchers shows that the design and implementation of citizen science projects is improving as practitioners learn from one another. For our part, we have learned several key lessons. Properly attributing citizen scientists’ contributions to publications and other projects resulting from the data is essential. Our website lists the names of everyone who has contributed data. We upload each year’s data set, with a short summary, to the site each year, and the data are freely available for anyone to use. We request that people who rely on this data cite their use of it—and recognize the volunteers with a link to our attribution page. New technologies are facilitating data collection, assisting with quality control, and improving data management. For instance, many citizen science projects are adding game components that broaden the appeal of the project and help motivate and retain volunteers. BudBurst has joined this trend, collaborating with BioTracker (a mobile-phone application for biological data collection) to create a “floracaching” game. The idea is similar to geocaching (in which people use GPS to find objects or clues hidden at precise locations): Players focus on locatingplants and making phenological observations. We are always working to improve quality control. An optional step in the registration process asks people to note their level of expertise in making observations of plants. Our mobile applica-

participation and support of our colleagues Kirsten Meymaris, Dennis Ward, Sarah Newman, Leah Wasser, Paul Alaback, Pati Vitt, and Jennifer Schwarz. And we thank the thousands of volunteers who have submitted their observations to Project BudBurst, without whom it would be impossible to improve our knowledge of plant phenology on such a scale. On April 2, 1856, Thoreau wrote in his journal of venturing out to find “evidences of spring.” On discovProject BudBurst materials are designed to be accessible for ering a particularly a wide range of ages. Here two students observe plants and record their notes on project data sheets. (Photograph courtesy early skunk cabbage (Symplocarpus foetidus) of NEON.) in bloom, he wrote, tion automatically geotags the location “Perhaps it is always earlier than I at which each observation is made, have thought, if you seek it in a favoreliminating the possibility of error in able place.” Later in the same entry, he determining the latitude and longitude wrote, “It will take you half a lifetime of the site. We hope to add a feature to find out where to look for the earlithat allows participants to upload pho- est flower.” Little did Thoreau know tos of the plants they observe so that we that his solitary searches would spawn can confirm reports of phenophases at scientific studies aided by the careful unusual times. We are also taking steps observations of a group of school chilto address the issue of spotty geograph- dren in Seattle, a retiree hiking in the ic coverage—the majority of reports Rocky Mountains, an educator moniwe receive are from cities. Many of our toring plants on a Colorado ranch, a more interesting findings are coming botanist in Chicago, and more than from places where we have continuous 15,000 other citizens across the counobservations of the same species over try. Citizen scientists today can choose multiple years. To spur local involve- to spend half a lifetime in search of ment, we plan to add data visualization earliest flowers, or they can spend tools that will allow users to explore an afternoon—but in any case, they their observations in the context of cli- will have the satisfaction of knowing mate data sets. that they and their observations are in Perhaps our most important chal- good company. lenge is the need to sustain both participation by volunteers and the project Acknowledgments as a whole over time. Initially, the Proj- In addition to Project BudBurst’s home ect BudBurst website was housed at institutions, we thank the following the University Corporation for Atmo- for their support: the U.S. Bureau of spheric Research (UCAR) in Boulder, Land Management, the National Fish Colorado. In fall 2010, it moved to its and Wildlife Foundation, the National permanent home at the National Eco- Geographic Education Foundation and logical Observatory Network (NEON), Society, the National Science Foundawhere it has extensive support for web- tion, the U.S. Fish and Wildlife Service, site maintenance. We are thus well posi- the U.S. Geological Survey, the USDA tioned to maintain and build on current Forest Service Southern Region, NASA, programs for decades to come. and many others. Our future sustainability will rest on a foundation of hard work and Bibliography thought from our colleagues and from Chung, U., L. Mack, J. I. Yun, and S.-H. Kim. 2011. Predicting the timing of cherry blosparticipants. We are thankful for the www.americanscientist.org

soms in Washington, DC and mid-Atlantic states in response to climate change. PLoS ONE 6: e27439. doi:10.1371/journal. pone.0027439 Dickinson, J. L., and R. Bonney (eds.). 2012. Citizen Science: Public Participation in Environmental Research. Ithaca, NY: Cornell University Press. Dickinson, J. L., et al. 2012. The current state of citizen science as a tool for ecological research and public engagement. Frontiers in Ecology and the Environment 10:291–297. Felker, W. 2008. Phenology and seasonal calendar. Poor Will’s Almanack: A Plain English Guide to Living in Harmony with the Earth. http:// poorwillsalmanack.com/06Phenology.html. Henderson, S., D. L. Ward, K. K. Meymaris, P. Alaback, and K. Havens. 2012. Project BudBurst: Citizen science for all seasons. In Citizen Science: Public Collaboration in Environmental Research, J. L. Dickinson and R. Bonney, eds. Ithaca, NY: Cornell University Press, pp. 50–57. Miller-Rushing, A. J., and R. B. Primack. 2008. Global warming and flowering times in Thoreau’s Concord: A community perspective. Ecology 89:332–341. Miller-Rushing, A. J., R. Primack, and R. Bonney. 2012. The history of public participation in ecological research. Frontiers in Ecology and the Environment 10:285–290. Newman, G., et al. 2012. The future of citizen science: Emerging technologies and shifting paradigms. Frontiers in Ecology and the Environment 10:298–304. Primack, R. B., H. Higuchi, and A. J. MillerRushing. 2009. The impact of climate change on cherry trees and other species in Japan. Biological Conservation 142:1943–1949. Primack, R. B., A. J. Miller-Rushing, and K. Dharaneeswaran. 2009. Changes in the flora of Thoreau’s Concord. Biological Conservation 142:500–508. Swink, F., and G. Wilhelm. 1994. Plants of the Chicago Region, 4th ed. Indianapolis: Indiana Academy of Science. Thoreau, H. D. 1906. The Journal of Henry David Thoreau. Boston: Houghton Mifflin. Chapter 6: April 1856. Available at the Walden Woods Project: http://walden.org/ documents/file/Library/Thoreau/writings/ Writings1906/14Journal08/Chapter6.pdf. Wolkovich, E. M., and E. E. Cleland. 2011. The phenology of plant invasions: A community ecology perspective. Frontiers in Ecology and the Environment 9:287–294.


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American Scientist - Project BudBurst

American Scientist - Project BudBurst

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