The harvest of the large shade-intolerant trees like the ponderosa pine, western larch, and western white pine and their replacement with homogeneous, small, dense stands of Douglas fir and various true firs enhanced the fire danger. Similarly with heavily grazed lands, grasslands and forbs gave way to increasingly woody vegetation such as sagebrush, juniper, as well as Douglas fir forests, adding considerably to the fire danger. In general the areas with the most forest health problems are areas that have been roaded and harvested. This interacts with the negative impacts of past fire suppression activities which are given a higher priority and are more effective in roaded areas. This leads to higher fuel buildups and fire dangers in the roaded areas.
Roads bring more visitors and more casual visitors.
With this comes more frequent human-caused fires. Homes increasingly are built up against National Forest boundaries, the parts of the forests closest to the regular system of county roads and the most likely part of the Forest to have already been roaded. This means that the highest risk of National Forest fires that threaten property and human lives are found in the areas already roaded and, usually, logged. The roadless areas tend to be remote, located many miles from human habitation. That is one of the reasons that fires in them are usually assigned a fairly low priority, allowing firefighters to concentrate on fires that represent more of a threat to commercial resources, property, and lives.