Nature watchers track clues to global warming
WASHINGTON – It has to do with water fleas in Lake Washington, brown-headed cowbirds and clear-cut forests, lilacs and wildfires, vineyards in the Rhine Valley, marmots, dandelions, tadpoles, cherry trees around the Tidal Basin in Washington, D.C., and musty old notes stuffed in shoeboxes in people’s closets and records stacked on museum shelves.
As scientists track global warming, they are using sometimes centuries-old data to assess its impact on plants, animals, insects, fish, reptiles and amphibians. Increasingly, they are discovering that it can take only one seemingly insignificant change to disrupt an entire ecosystem.
“People talk about a one or two degree rise in temperature, and it’s inconsequential to us. Who cares?” said Greg Jones, an environmental studies professor at Southern Oregon University who has been studying wine grapes. “But in an ecosystem it can have dramatic effects.”
As the study of phenology, or life cycles, attracts growing attention, researchers are turning more and more to citizen scientists for help.
Since 1954, more than 1,000 people nationwide have monitored lilacs, recording when they first develop leaves, buds and blossoms in a program that started in Montana and is now part of the National Phenology Network. The data can now be submitted online.
Another 3,500 or so people are monitoring 4,500 different plants as part of Project BudBurst, another online program. Eventually, those involved in the project would like to have 40,000 people tracking plants, shrubs and trees from kinnikinick to chokecherry and wheat to Western columbine.
“The biggest hit has been dandelions,” said Jake Weltzin, a scientist with the U.S. Geological Survey who is executive director of the National Phenology Network. “Everyone cares about dandelions.”
Besides scientists and professional land managers, kindergartners, master gardeners, farmers, fishermen, and bird, frog and butterfly watchers have participated. Weltzin said that every time he speaks with a garden club, about one in every five people attending have detailed records tucked away on their plants, trees and shrubs.
Next year, the phenology network is launching a new program to monitor wildlife and track such things as bird, fish and mammal migration.
“It’s easy to observe when the plants in your garden flower or when the birds arrive at the feeder in your yard,” said Abraham Miller-Rushing of the Wildlife Society.
Stored in cabinets at the University of Washington’s Burke Museum are 12,000 file cards dating to 1955. The cards, according to curator Sievert Rohwer, provide a gold mine of information on the birds of the Pacific Northwest. The museum receives hundreds of cards a year from people who are tracking more than 100 species of birds. The museum unsuccessfully sought a National Science Foundation grant to organize the information online.
“It’s a critical database that is enormously valuable,” Rohwer said.
The data includes information on tree swallows, a bird found across North America that lives mostly in forest fringe areas. A study done by scientists at the Cornell Laboratory of Ornithology has found the birds are laying their eggs 10 days earlier than they were in 1959, a change that could be linked to global warming.
While the Cornell study didn’t use data from the Burke Museum, Rob Faucett, the museum’s collection manager for birds, said he was convinced it would confirm the findings. In addition to the data, Faucett said the museum has tree swallow eggs dating back as far as 1885.
“We are like a library as opposed to a research lab,” he said.
Technically, phenology is the study of the seasonal timing of plant and animal life cycles, including such things as animal and bird migrations, emergence from hibernation, and blooming, leafing and flowering. Over the past 10 years it has increasingly become a mainstay in the study of climate change, as life cycles are thought to be highly sensitive to global warming.
Using data from official and unofficial sources, scientists say spring, on average, is arriving roughly a week earlier than 50 years ago. That has caused ripple effects in natural ecosystems. For instance, if plants bloom earlier, insects and birds must adjust. Some species might respond better than others. Those that don’t could disappear.
“It’s clear changes in phenology are an early warning sign of climate change,” said Daniel Schindler, an associate professor at the UW School of Aquatic and Fishery Sciences.
Using 40 years of detailed records, Schindler and his colleagues concluded that Lake Washington, east of Seattle, is awakening from its winter slumber and the spring algae bloom is appearing three weeks earlier than in the past. That’s affecting water temperatures in the lake and the growth of phytoplankton and the zooplankton that feed on them.
While salmon, in turn, feed on zooplankton, Schindler said scientists aren’t sure yet what the effect will be. But Schindler said daphina, or water fleas, that help clean the lake by eating algae or phytoplankton are appearing in lower densities.
“We haven’t made the direct link, but there could be implications for water quality,” he said.
Using records dating to 1784, Southern Oregon University’s Jones said that the bud break for wine grapes in Europe’s Rhine Valley is coming three weeks earlier than 50 years ago. Pests like mites and aphids have to adjust to the new time schedule, as do the ladybugs that eat them. But Jones said the real problem might be that the grapes are maturing earlier and have to be picked in the heat of the late summer. That could affect quality. Wine grapes are best when harvested in cooler fall temperatures.
Perhaps the classic example of the impact of climate change on an ecological community is oak trees in the Netherlands. The trees are leafing out earlier. The winter moth caterpillars that feed on the leaves are coming out earlier. But the pied flycatchers that eat winter moth caterpillars remain on the old schedule as they migrate from central Africa to the Netherlands. In some areas, the populations of pied flycatchers have dropped 90 percent.
“There are similar stories everywhere,” said Miller-Rushing.
The cherry trees in Washington, D.C., are flowering earlier, marmots in the Rocky Mountains are emerging earlier, butterflies are moving farther north and, in some cases, have become practically an invasive species, and everything from prairie dogs to tadpoles and apples to peaches are being affected, said Weltzin.
Lilacs, however, have so far been the star of the program, he said. They are a common plant, they grow almost everywhere, and their life-cycle changes are easy to observe. But as opposed to many plants, lilacs might actually be blooming later because of climate change. Weltzin said lilacs need their winter sleep, and the warmer and drier it is, the later they wake up.
“It’s very counterintuitive,” he said.
In general, Weltzin said, if lilacs in the West bloom after May 20, it’s going to be a major forest fire season.
“We need to know how all these organisms respond to climate change,” Weltzin said. “We call it the pulse of our planet, or timing is everything.”
Les Blumenthal: 202-383-0008
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