As a Peace Corps Volunteer in Paraguay, Samuel Hagler was stationed 12 kilometers from the San Rafael Reserve, a government-protected zone of the Upper Paraná Atlantic Forest. He soon found the term "reserve" didn't mean much: With the help of bribed officials, the old-growth forest was being destroyed to make room for farmland and pastures. So last year, Hagler launched the Ride for the Trees, a solo bicycle trek from Paraguay to the United States, with the goal of raising money and spreading the word-all while hauling everything from camp stove to laptop.Hagler acknowledges that the bike ride has become a weirdly ubiquitous donation tool. "For some reason bicycle tours have become synonymous with fundraisers," he says, checking in from Panama. But with Ride for the Trees, the cycling itself seems relevant. At the scale of 15 miles per hour and a couple towns per day, Hagler can be reflexive: When he sees some trash, he picks it up. If there are people to talk to, he talks. "When I roll by schools at recess time I often stop to ask if we can play some environmental games with the students," he says. He's also creating his own education, and he finds he gets to learn more on two wheels: "Because I pass through so many distant towns I hear a lot of stories of corruption and exploitation that don't make the news."The ability to ad-lib has been critical. Hagler rarely knows where he'll bed down on a given night. "I have slept in kitchens, churches, the bed of a fruit truck, a jail cell," he says. And things can go wrong in a flash. The worst? "A freak killer bee attack in Argentina." The weirdest? "In Ecuador I was captured by police and accused of head-shrinking." The most ironically tree-related? The night he "woke up covered in leaf-cutter ants because they had cut hundreds of holes in my tent."Learn more at the Ride for the Trees blog.