In the fall semester of alternate years, I teach a course called Land Protection (GEOG 332). It is the epitome of environmental geography class in that it examines the interface between physical and human geographies. In this case, we study forest ecology and landscape change as it relates to conservation policy and related elements of the tax code. It's a fun course, really, and many who take it go on to work as volunteers or professionals in conservation.
One of the texts in that course is Thoreau's Country, in which author David Foster compares observations from Henry David Thoreau's daily journal with his own observations of New England forests, especially those he has made as the long-time director of the Harvard Forest in Petersham. I take my students to that forest -- almost all of which would have been agricultural land in Thoreau's day -- for some close-up examination of landscape change. Over the years I've been aware of various kinds of research going on in the forest, including snow studies by a friend of mine and long-term climate studies under the auspices of the United Nations.
It is at about 22m45s into the On Point installment that the caller Susan discusses her research into the mental-health benefits of walking, particularly in the woods, and by extension a key benefit of maintaining public open space. She has been learning more about these benefits through research in the very same woods that I was visiting in order to fine-tune the forest-ecology exploration I will be repeating in the autumn.
Humorist Bill Bryson has written a very different book with a similar title, which I have read with students in another context and that I highly recommend -- A Walk in the Woods: Rediscovering America on the Appalachian Trail.