He was an early forest preservationist, often consulting for US forester Gifford Pinchot, regarding developing national forests in California. He became an activist in the Sempervirens Club, devoted to protecting the coast redwood (Sequoia sempervirens), and was key to establishment of what is now Big Basin Redwoods State Park in the Santa Cruz Mountains.: In 1901 the California Legislature passed an enabling act whereby of land were purchased by the state in the next year to preserve the coastal redwood forest throughout the Santa Cruz Foothills area. Dudley was one of four men appointed to the first state board of commissioners. Big Basin Redwoods State Park was established in 1902, the first of many in that state created since then.