wallace has tried to couple his writing with conservation activism. he has been an advocate of parks, wildlife and wilderness protection in several areas, especially the klamath/siskiyou mountains region of northwest california and southwest oregon, the subject of four of his books (including the klamath knot) and central america from chiapas to panama, the subject of three of his books (including the monkey's bridge). biologist daniel janzen called his 1992 book, the quetzal and the macaw: the story of costa rica's national parks, "a major contribution to tropical conservation." his 2007 book, neptune's ark, explores the evolution of western north america's marine megafauna, one of the world's most important although less well known than terrestrial ones. his 2011 chuckwalla land explores the evolution of california's desert, which is still not well understood despite many theories about it. botanist bruce pavlik called it "a clear and entertaining story about the origin of california's desert that invites the reader into a world of ancient mystery and modern revelation."