A Classification Of Forest Habitat Types Of The Southern Arizona And Portions Of The Colorado Plateau

The book provides information essential for anyone interested in the ecology of the American Southwest, including land managers, environmental planners, conservationists, ecologists and students. It is unique in its coverage of the hows and whys of dynamics (changes) in the major types of vegetation occurring on southwestern mountains and plateaus. It explains the drivers and processes of change, describes historical changes and provides conceptual models that diagrammatically illustrate past, present, and potential future changes. All major types of vegetation are covered: spruce-fir, mixed conifer, and ponderosa pine forests, pinyon-juniper vegetation, subalpine-montane grassland, and Gambel oak and interior chaparral shrublands. The focus is on vegetation that is relatively undisturbed, i.e., in natural and near-natural condition, and how it responds to natural disturbances such as fire and drought, as well as to anthropogenic disturbances such as fire exclusion and invasive species

Birds are indicators of vegetation structure and ecological conditions. The singing activity of birds declines during late-morning periods, which can affect estimates of abundance and conclusions regarding vegetative conditions indexed by birds. Therefore, it is important to quantify periods of bird activity so biologists can plan studies. We determined hourly detections from singing males of 22 nongame bird species in ponderosa pine, quaking aspen, and grassland vegetation types in the Black Hills of South Dakota. Detections of 12 of 22 species differed among 1-hr intervals after sunrise. Detections of yellowrumped warblers, Townsend's solitaires, red-breasted nuthatches, western tanagers, and American robins decreased on count-episodes more than 4 hrs after sunrise. Detections of dusky flycatchers declined on count-episodes more than 3 hrs after sunrise and detections of black-capped chickadees were greatest during the first hour after sunrise and declined afterward. Detections of many other species from songs or calls decreased on count-episodes more than 5 hrs after sunrise. We recommend that bird counts in the Black Hills be completed within 4 hrs after sunrise so estimates of bird abundance are not affected by reduced singing among males.