As founder of the modern environmental movement, Rachel Carson's legacy would seem secure.

Environmental experts recently ranked the author of "Silent Spring" as the world's most influential environmentalist. In 1999, Time Magazine named the Springdale native as one of the 20th century's most important people. Pittsburgh's Ninth Street Bridge has been renamed in her honor.

But 100 years after her birth, the Rachel Carson Homestead Association in Springdale hopes to assure her legacy never wilts, with planned celebrations of her life and works.

Patricia DeMarco, association executive director and University of Pittsburgh biology professor, announced yesterday at the Regional Enterprise Center that the Rachel Carson Centennial Celebration will include four events:

During a legacy challenge April 20 at the Senator John Heinz Pittsburgh Regional History Center, people, businesses, organizations and public and private institutions will be encouraged to change behavior and policies to promote Ms. Carson's environmental ethic. Her ethic promotes living in harmony with nature, preserving and learning from nature, minimizing impact of man-made chemicals, and considering implications of human actions "on the global web of life."

A block party at the Rachel Carson Homestead in Springdale will be held May 27, her birthdate in 1907. The event will include tours, a one-woman play, "Rachel Carson's Sense of Wonder," and food produced by local farms that practice sustainable agriculture.

The inaugural Rachel Carson Legacy Conference will be held Sept. 29 at Carnegie Mellon University on "Sustaining the Web of Life in Modern Society" and other environmental topics.

Discussions during a multifaith "Spirit and Nature" gathering Nov. 3 at Chatham College will focus on the reverence for nature in world religions and other environmental topics. Ms. Carson graduated from the Pittsburgh College for Women, which became Chatham College.

During the announcement, Allegheny County Chief Executive Dan Onorato heralded Ms. Carson's legacy by noting how industrial sites and waterfront properties have been transformed into greenfield developments.

"Being green isn't a financial liability -- it can be an economic benefit," Mr. Onorato said. "This woman saw an idea 50, 60, 70 years ahead of what we see here today.

"It's an honor she's from Allegheny County."

Published in 1962, "Silent Spring" focused on environmental devastation of pesticides. Ms. Carson's testimony before the U.S. Senate eventually led to a 1972 ban on the pesticide DDT. She died of breast cancer in 1964.

Her work sparked "a green revolution" and environmental activism, Dr. DeMarco said.

An original critic of her book, Time said in 1999 that it was "well crafted, fearless and succinct." It said "even if she had not inspired a generation of environmental activists, Carson would prevail as one of the greatest nature writers in American letters."

Dr. DeMarco said the Web site, www.rachelcarson.org, is now online. The association also offers environmental health and educational programs for children and adults.