Sites photographed for each series were selected to show a range of conditions of several site attributes depending on the ecosystem type.  For example, the Alaska hardwood photo series displays sites in order of their relative density of spruce and hardwood trees (Figure 1).

Photographs were taken, and fuel loading, stand structure, and vegetation composition data were collected using standardized sampling procedures.

Each photo series generally displays one wide-angle photograph and at least one stereo photo pair per site. 

In certain ecosystems, additional photos were taken to demonstrate, for example, leaf-on and leaf-off conditions in deciduous forests.