Disturbed lands are defined generally as those impacted by human activities, both historic and current. At Pictured Rocks, these activities include logging and mining practices during the past 150 years, fires resulting from these practices, road improvement projects, land clearing for agriculture, and vacation home development.
The effect of these activities, especially logging, is particularly evident in the forests of the national lakeshore. Logging that took place from the mid 1800s to the mid 1900s removed the old-growth forest, which greatly impacted the structure and composition of today's forests. The average age of mature trees throughout the park is around 100 years old and few old-growth specimens remain. Non-native tree disease (such as Dutch elm and beech bark diseases) and repeated fires have caused significant change as well.
Evidence of former land use is also found in the presence of successional fields and other remnants of historic farms. Large-scale farming did not occur at Pictured Rocks and only a few sites still remain along with some aging apple orchards. Before the park was established in 1966, there were a variety of vacation cottages and other buildings within what are now park boundaries. These buildings were eventually removed and roads to these structures were closed and allowed to revert back to natural conditions.
Whether or not a disturbed landscape is considered problematic depends on the purpose for which it is being managed. For instance, if the goal is to create an open area such as the firebreak historically maintained at the Au Sable Light Station (in order to preserve the cultural scene at that location), then keeping the area open and removing woody vegetation that encroaches upon this scene is a necessary disturbance.
Land use practices outside of park boundaries are of special concern to park managers. Disturbed lands are highly vulnerable to invasion by non-native plant species that can spread quickly. Fragmentation of ecosystems by roads and other development interrupts important wildlife corridors. Many of the streams and rivers that flow through the park have their headwaters in private land outside park borders. Wildlife populations travel freely between the park and outside lands, and are therefore vulnerable to stresses that may be present, such as disease, pollution, diminished water quality, lack of biodiversity, and habitat loss.
Even in this sparsely populated region of Michigan, there is concern about how development in adjacent communities will affect the park. A 2009 NPS study of road development and building growth around Pictured Rocks showed that growth rates increased significantly after the park was established. The study suggests that parks themselves can contribute to increased development near their borders as local communities build infrastructure, motels, restaurants, and other amenities to accommodate ever higher numbers of park visitors.
Since national parks increasingly impact and are impacted by external events, one important goal of the national lakeshore's resource management program is to take a greater role in regional resource issues. Pictured Rocks works with other Midwest parks, Canadian parks, and local and state agencies in a joint effort to manage resources within the Lake Superior Basin.