David grew up in the San Francisco Bay area with a family that often camped. He spent much of his youth backpacking in the Sierra Nevada which sparked his interest in pursuing a career in wilderness and recreation research. While studying geography at the University of California, Berkeley, he discovered he could get credit doing projects in the wilderness of Point Reyes and Big Sur’s Ventana. In graduate school at the University of Oregon he decided to do his dissertation in the Eagle Cap Wilderness, after seeing a picture of Glacier Lake on the cover of a 50 Hikes in Oregon book. Wondering what he could study that could get him there, he settled on studying human impact on vegetation. At Oregon, he had the good fortune of meeting Bob Lucas, project leader of the Forest Service’s Wilderness Management Research Work Unit, also a geographer, who had gone to graduate school with some of the Oregon professors. In 1978, Bob gave David a temporary position with the Wilderness Management Research Unit and David has been there ever since.

During the 30+ years David has been with Forest Service Research, with the Wilderness Management unit and the Aldo Leopold Wilderness Research Institute, he has focused on the discovery and synthesis of knowledge that contributes to the preservation of natural and untrammeled conditions and quality visitor experiences in wilderness. Notable about his career is the breadth of his expertise. He has honed technical knowledge in both the ecological and social sciences, as well as developed great skill in integrating research in ecological and social sciences.

His initial work was primarily on the ecological impacts of recreation, a field in its infancy, with little coherence. He did original research but worked particularly to organize and synthesize recreation ecology research and explore its implications for wilderness management. This work culminated in a chapter on recreation impacts in the Wilderness Management textbook, a state-of-knowledge paper at the 1985 Wilderness Science conference and co-authorship of the first textbook on recreation ecology. Based on this work, he is recognized worldwide as an expert in recreation ecology. He has been an invited organizer or instructor at workshops on this topic in Canada, Australia, Chile, Austria, Finland and the United States. He has mentored a number of students who have become the second generation of recreation ecologists in the United States.

David has worked hard to make his science as useful to managers as possible. He worked with the Forest Service and National Outdoor Leadership School to use recreation ecology results to inform what became the Leave No Trace principles and practices and then coauthored the first book on the subject, Soft Paths, now in its fourth edition. About 20 years ago, he turned some of his energies from studying how visitors impact wilderness to how impacted sites can be restored. In this arena, he has done experimental work in the Eagle Cap and Sawtooth Wildernesses and coauthored a Forest Service manual on Site Restoration. More recently, he turned to doing work on visitor experiences in wilderness, culminating in the recent publication of a proceedings on what has been learned in the first 50 years of research into wilderness visitor experiences.

He led a Forest Service effort to accelerate the application of indicator-based planning frameworks, particularly the Limits of Acceptable Change, both within and outside the United States. Recently this work has been adopted by other agencies managing wilderness, with the chartering of a new Interagency Visitor Use Management Council, for which David has been the primary scientist. Campsite and trail monitoring methods, developed by David and others, are being applied around the country and the world.

Beyond recreational issues, he has contributed critical thinking about wilderness stewardship goals, particularly what constitutes "natural" and “untrammeled” conditions. He recognized problems with the traditional goal of naturalness in an era of increasingly rapid and unpredictable human-caused change, exemplified by climate change and brought together a wide range of thinkers to explore problems and suggest new ideas and concepts. His efforts have resulted in the recent publication of the book, Beyond Naturalness, as well as a number of articles and presentations. This work is already being taught in classes and being used to rethink agency policy.

David has been honored with a number of awards for his work. In 1997 he was awarded the Theodore and Franklin Roosevelt Award for Excellence in Recreation and Park Research by the National Recreation and Park Association. This award recognizes career contributions and is "presented annually to the individual whose contribution to recreation and park research has significantly advanced the cause of the recreation movement." It is the most prestigious award a recreation researcher can receive from the recreation profession. At the wilderness Science conference held in Missoula in 1999, he received a special award from the Chief of the Forest Service, again for career contributions, in “special recognition for long-term research applications to wilderness management.” In 2002, he was awarded the National Park Service’s Director’s Award for Natural Resource Research—given each year to their “Scientist of the Year”. In 2011, he was given the Natural Resources Achievement Award by the George Wright Society, the professional organization devoted to the application of science to parks and protected areas. Also in 2011, the National Outdoor Leadership School gave him their Stewardship Award, given each year to “an individual who has exhibited exceptional stewardship of public lands and the environment.”

David retired at the end of 2013 and transitioned to Scientist Emeritus status at the Institute and a new chapter in life. He taking more time to enjoy the wilderness, while still contributing to wilderness science and maintaining his many professional and personal relationships in the wilderness community.