FIRE PROTECTION IN FORESTS OF THE WESTERN UNITED STATES HAS INCREASED THE DENSITY OF TREE POPULATIONS
FIGURE 7.19 Historically, ponderosa pines in Arizona and elsewhere in the American West grew at low densities, producing a parklike landscape. After decades of fire protection, however, the densities of ponderosa pines in these landscapes increased to unsustainable levels.
(W. J. Lubkin, USDA Forest Service) (Dennis Simmerman, USDA Forest Service)