I like the Peterson Forest field guides like this one because rather than helping you identify a full range of endemic species of plants or animals, it tries to encapsulate the key characteristics of the region's ecological zones. So in this guide you learn about the dominant or indicator species of various areas of the west (from Sonoran desert to boreal forest), why going up a mountain ends up being like an ecological trip hundreds of miles northward, and what effects climate and rainfall have on the species found. I felt like in a short period of reading that I could understand what's going on in a redwood forests compared to a giant sequioa grove, or why certain areas of oregon have douglas firs and others have oak-pine forests. ( )