Naturalists at Greenbrook Sanctuary in New Jersey, have methodically walked the woods on spring mornings for more than three decades, recording the arrival of migrating songbirds, the season's first amphibian croakings and the earliest wildflower and tree blooms.

Their jot-filled notebooks have stacked up, virtually ignored, since 1976. But they have suddenly taken on new scientific significance for a university professor researching how climate change could affect Northeastern forests.

Eastern Kentucky University's Neil Pederson, who specializes in old-growth forests, is using the Greenbrook records to determine whether climate change has influenced the bloom times of the sanctuary's red maple and tulip poplar trees — and if that information can help scientists predict how future climate change will affect vegetation and wildlife.

"There's a lot of uncertainty in scientific data, but this is a great data set because there have been only two main observers over the years," Pederson said.

The data gathering — called phenological observations — was started at Greenbrook in 1976 by John Serrao, the naturalist at the time. When he left in 1986, his successor, Nancy Slowik, continued the practice.

"I always knew someday they'd come in handy," said Serrao, who now lives in the Poconos in Northeastern Pennsylvania.

In fact, growing numbers of researchers are turning to the observational records of naturalists and "citizen scientists" across the country for data that will help them learn more about the effects of climate change. A group of universities has even launched a Web site, called Project BudBurst (www.windows.ucar.edu/citizen—science/budburst/), to spur citizens to collect more data.

"The environment is changing very rapidly, and there will be some winners and losers. We want to be able to predict which species will be affected so we can adjust our management practices," said Abraham Miller-Rushing of the National Phenology Network and The Wildlife Society. "But one of the big limitations of predicting the impact of climate change is the lack of available data. As we find more people who have kept good records, it's adding a lot of useful information for researchers."

Those who started the 136-acre Greenbrook Sanctuary, nestled atop the Palisades in Tenafly, N.J., seemed to understand that intuitively. When Serrao arrived at Greenbrook, he came across phenological records dating from the sanctuary's founding in 1946, but the records ended in the 1950s. Serrao decided to resume the practice.

He'd walk the trails each spring morning, noting the new blooms, birds and animals. "I tried to follow the same procedure each day," he said.

He saw trends — such as the disappearance of certain migrating warblers. "The first theory among naturalists and scientists was that they were losing their tropical habitat," he said. Serrao said another possibility was a change in their New Jersey habitat, with development having fragmented remaining open space.

As he continued his observations, Serrao realized the sanctuary was also losing some frogs, snakes and salamanders.

Serrao befriended Daniel Smiley, a naturalist at Mohonk Mountain House in upstate New York. Smiley kept detailed phenological records and weather observations — even testing Lake Mohonk for acidity, which was not typical at the time. The readings were vital when scientists started studying the impact of acid rain.

The two would compare notes. "We discovered the same species I saw disappearing at Greenbrook were also disappearing up there," Serrao said.

Slowik continued Greenbrook's observations, noting the arrival of the first Baltimore oriole and blackthroated green warbler each year, the first painted turtle sunning by the pond, the bloom dates of lady slipper orchids.

"What's important here is consistency," Slowik said. "We have staff on duty year-round. The consistency makes the data that's collected here more important."

Over time, more species came and went. The roughed grouse, which used to breed in the sanctuary, was last recorded in 1994. That likely occurred because the sanctuary's stands of hemlock, which provided cover and food for the grouse, were wiped out by an infestation of woolly adelgid.

On the other hand, bloodroot, a perennial flowering plant, showed up in 1994, and 1995 saw the first sighting of the eastern coyote in the Greenbrook woods.

Because plants live in the same location permanently, they are often a better indicator of climate change than migrating birds, Slowik said.

For his research, Pederson focused on the bloom times of the red maple and tulip poplar.

He and Eastern Kentucky colleague Donald M. Yow combined Greenbrook's data with weather data for the area and ran some computer models. They found that the maximum daily temperature in March seemed to affect the red maple's bloom time. They also found that the number of days with temperatures above 68 degrees in April helped determine when the tulip poplar blooms.

If average temperatures rise and cause shifts in bloom time for plants, bird or butterfly species dependent on those plants for food might have to adjust their migratory behavior or find alternative food supplies, Miller-Rushing said.

"Across North America, the 100-year record shows spring arriving earlier," Pederson said.

Pederson, raised in rural upstate New York, said a lot of global warming research is carried out far from Northeastern forests.

"I'm interested to find out what could happen in our own back yard," he said. "I like these forests."

Serrao agrees, and wonders why so few people explore them anymore. Americans suffer from "nature deficit disorder," he said. "Kids are at their computer or watching TV and video games. That has contributed to America's problem with obesity.

"It also reduces our capacity to appreciate nature, and in turn to protect it."

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