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Study Calls on 'Citizen Scientists' To Tap Their Inner Thoreau

By Adrian Higgins
Thursday, January 29, 2009

Even with the ground frozen and the fish pond glazed this month, there are signs of life.

The first brave blossoms of winter jasmine are shivering in freezing temperatures. Daffodil shoots are rising through the rock-hard soil, and pearl-like snowdrops are just apparent through the golden and lifeless foliage of the hakone grass. (I must cut that back.)

Gardeners notice these seasonal progressions even in the supposed dead of winter, and for that reason, a U.S. Geological Survey ecologist named Jake Weltzin wants to tap into the vast reservoir of knowledge that exists in America's back yards.

"I would like to have 40,000 plant observers," said Weltzin, who is based at the University of Arizona at Tucson and is executive director of an organization called the USA National Phenology Network. Phenology is a bloodless scientific term for the miracles that occur every day in the garden: the morning in March a flock of cedar waxwings alights on the holly bushes, the first unfurling of the dogwood flower, the day the hummingbirds return, or the hour the frog lays her eggs. These life cycle events combine to form the tapestry of the natural world, and the more plants we use in the garden and the more wildlife we attract, the richer the experience.

Weltzin and his colleagues have a more prosaic reason to call on gardeners and backyard naturalists to log these phenomena: They are starting a 30-year project to gauge how climate change is affecting the world around us.

"Citizen scientists" are vital to the success of the program "to get the density of observations we need," he said.

The network has established a plant phenology program and Web site (http://www.usanpn.org) that is about to be revamped for the 2009 season to be more user-friendly while refining the program's reporting protocols. After the late-winter redesign of the Web site, participants will be able to record their observations at three levels: as a novice under Project BudBurst, or at an intermediate or more skilled scientific level. Participants are asked to observe the life cycles of plants chosen from a list of 70 to 203 garden plants, shade trees, wildflowers and weeds. No garden? No problem. Trails, parks and public woodlands all offer opportunities for recording information.

Next year, the network hopes to launch a similar site for recording wildlife and is working to nail down 120 animal species for people to observe and record, 20 each among mammals, birds, reptiles, amphibians, aquatic species and insects.

The unwitting father of this endeavor died 147 years ago. Henry David Thoreau, abolitionist, philosopher and naturalist, spent six years recording the flowering dates of 500 plant species of his native Concord, Mass., with the aim of producing a calendar based on a plant's first flowering.

Such was the scale of his task, and his legendary status as a naturalist, that his work inspired others in Concord to follow suit. Alfred Hosmer, a shopkeeper and amateur botanist, recorded the flowering times in various habitats of 700 species and varieties between 1878 and 1902. And from 1963 to 1993, Pennie Logemann, a landscape designer in Concord, methodically logged the bloom patterns of 250 plants. "I especially loved wildflowers," the now-retired Logemann said in an interview, "and more of my work was done with wildflowers than cultivated plants." She added, "I just noticed from year to year that something was going on."

All three sets of records have begun to give scientists a painfully clear picture of how global warming has affected our flora and fauna. Researchers at Harvard and Boston universities went back to Concord between 2003 and 2006 to record flowering data for 500 species (60 percent of Concord's green spaces have remained intact since Thoreau's day). They determined that temperatures have risen nearly 4 degrees in the past 150 years, that flowers now open a week earlier on average and that some plants are far better equipped to deal with this phenomenon than others. More than 60 percent of the plants Thoreau tracked either have gone extinct locally or are on the brink of disappearance.

"Orchids have declined, as have lilies and gentians; these are some of the most charismatic plants," said Abraham Miller-Rushing, one of the researchers and coordinator of the impending wildlife project.

Strikingly, the scientists found that plants that adapted to temperature changes, particularly in January and early spring, were survivors compared with those that continued to bloom at the same time as when Thoreau trudged the gardens and woods of Concord.

"Species that have not flowered earlier have declined in abundance," wrote Miller-Rushing and his colleagues in a recent issue of Proceedings of the National Academy of Sciences. These include asters, mints, orchids, saxifrages, lilies and violets.

Insect life cycles also have shifted, leading the researchers to wonder whether the declining plants have lost their traditional pollinators.

For the plants that have responded to warming, first-flowering dates have advanced markedly in some cases. The high-bush blueberry now flowers three weeks ahead of its 19th-century appearance. The wood sorrel, a common yellow flowering weed, blooms a month earlier.

Similar patterns have been seen in the Washington area, though over a shorter study span.

More than 100 observers recorded first-flowering dates in about 100 species over 32 years, ending in 2001, and found in 90 of them an average advance of flowering of more than five days. The data were analyzed in a study by botanists at the National Museum of Natural History. The plant whose first flowering has advanced the most is a weed called false strawberry, now blooming 44 days ahead of schedule. Other, more familiar plants are the redbud (nine days earlier), flowering dogwood (eight days), Virginia bluebell (16 days), Yoshino cherry tree (nine days) and dandelion (24 days).

Stanwyn Shetler, curator of botany emeritus at the museum, welcomed the National Phenology Network's continuation of the effort. "Citizen scientists is [a concept] they have made a high art of in ornithology, engaging thousands of people across the country. I don't see any reason why one couldn't or shouldn't have something like that dealing with plants and phenology."

Researchers suggest a number of widespread plants that gardeners and naturalists could use to track climate change, including the weed chicory, with its distinctive blue flower in early summer; a St. John's wort species named Hypericum perforatum; the blueberry bush; and the water iris named blue flag.

"We want people in urban areas, rural areas. We are really going to need the backyard naturalists to help out," Weltzin said.

In short, a nation of Thoreaus. "He didn't realize it at the time," said Miller-Rushing, "but the observations he was making would be valuable to our understanding of climate change."

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