William Sullivan has written 21 books extolling the virtues of Oregon and its wildlands. Now he's going to bat to protect some of those wildlands from efforts by the Trump administration to pare back the Cascade-Siskiyou National Monument.

Sullivan, whose books include "100 Hikes in Southern Oregon and Northern California," will speak at two early November events in Medford and Ashland about his travels, local trails and threats to national monuments.

Sullivan, a Eugene resident with roots in the Rogue Valley, says he expands and updates his hiking books every two years. He is now elucidating on “endangered trails” that stand to be wiped out if national monuments are pared back, as recommended by federal officials, he said.

He said the emphasis of his talks will be on trails at risk of being eliminated if the Cascade-Siskiyou and other national monuments are reduced. The 113,008-acre Cascade-Siskiyou monument was one of four national monuments recommended for reduction by Interior Secretary Ryan Zinke after a review ordered by President Donald Trump. In all, he recommended protections be reduced for 10 national monuments. Trump has not yet taken action on the recommendations.

“It’s all pretty frightening in a way," Sullivan said in a phone interview, "because a president has never undone a national monument, and if you start, it’s a dangerous road, because you could lose all the monuments and national parks with a president who wants to commercialize them."

Sullivan said monument supporters question whether the president's expected action would even be legal.

"Once you set it aside, it’s permanent — or it’s always been that way. Here in Southern Oregon, it’s ground zero, one of the few places in the country that’s a test site to see if a national monument can be privatized and developed. Once created, the idea is that they’re preserved for all time.”

Sullivan's talks will also touch on a variety of regional trails.

His fourth edition of “100 Hikes in Southern Oregon” includes a dozen new or radically changed trails within two hours of Medford-Ashland, including trails at Crater Lake and in national forests on both sides of the California/Oregon border. It also has a 32-page travel guide of highlights in the area.

The book is part of a five-book "100 hikes" series, including "100 Hikes in Northwest Oregon & SW Washington," "100 Hikes in the Central Oregon Cascades," "100 Hikes/Travel Guide: Eastern Oregon" and "100 Hikes/Travel Guide: Oregon Coast & Coast Range."

Sullivan writes a regular column, ”Oregon Trails," for the Eugene Register-Guard and Salem Statesman Journal. In 1985, he set out on a 1,361-mile solo backpacking trek from the state's westernmost shore at Cape Blanco to Oregon's easternmost point in Hells Canyon. His journal of that two-month adventure, published as "Listening for Coyote," was chosen by the Oregon Cultural Heritage Commission in 2005 as one of the 100 most significant books in Oregon history.

Sullivan will discuss new trails above Ashland, including the Red Queen, Bandersnatch and Mike Uhtoff trails, and efforts to build trails to separate hikers and mountain bikers.

The Alice in Wonderland trail was illegally built by bikers on private land in the Ashland Watershed and has become eroded and dangerous, so the city of Ashland is in the process of buying it and giving it a better design, he said.

Sullivan will speak at 6:30 p.m., Thursday, Nov. 2, at the Medford REI on "New Hikes in Southern Oregon." The audience is limited to 40 people, and all the spots are already full, according to REI's website.

Sullivan will talk and give a slideshow at 6:30 p.m. Friday, Nov. 3, at a fundraising event for the Friends of the Cascade-Siskiyou National Monument at Chouse (a church converted to a house), 100 Sixth St., in Ashland. The cost of the talk and dinner is $75, and requires reservations, said organizer Susan Roudebush.

For reservations, email susanroudebush@mindspring.com. For more information, see www.cascadesiskiyou.org/calendar-of-events/

Sullivan’s website is www.oregonhiking.com/william-l-sullivan. His books are available at Northwest Nature Shop and most outdoor stores and book stores.

— John Darling is a freelance writer living in Ashland. Email him at jdarling@jeffnet.org.