Here is an image showing the extent of the forest that was mapped for the D.F.I. project. Click on the image for a closer look.
Summary statistics were generated two ways.
First, forest data summary statistics were generated for the entire study area, which can be seen above.
Looking at the image above, we can see that approximately 48 percent of the land area within the city limits is forested land. Except for the neighborhoods considered "downtown" (i.e. numbers 3,5,6 and 7), the forested area is divided fairly evenly. Also notable are the large patches of contiguous forest cover, which for the most part, comprise the city forest parks. The maps located here give a more detailed look at the city forest park lands.
Patch size and frequency are important when analyzing forest landscape for a number of reasons. First, large patches of contiguous forest cover serve as very different habitat areas compared to a more "patchy" landscape. In an urban setting such as Duluth, many factors contribute to this smaller patch sizes. Roads, housing, retail and corporate developments all divide large regions of contiguous forest cover into scattered, isolated regions. This has particular concern for certain species with larger territorial needs such as birds, some of which prefer to stay away from open areas. Their "flyways", which are provided by large expanses of forest cover, can be dissected by the simple addition of a paved road or forested lawn. Another common example which most are familiar with are the all too frequent "roadkill" type accidents. These are the result of animals trying to survive in road fragmented landscapes. Simply put, their territorial range has been split up by human influences.
This chart summarizes the D.F.I. forest cover using six categories. These categories were obtained by grouping the 43 minor categories. Here is a table showing which species fit into each of the major categories.
Next, the neighborhood planning district boundaries were used to clip the forest cover and summary statistics were created from this clipped layer. Of particular interest are the percentages of aspen / birch. These "early successional" growth species dominate in every neighborhood planning district and this clearly demonstrates these species' ability to thrive after a "older growth" type forest matures. Certain species, such as oak, yellow birch, sugar maple, and basswood can live up to 200 years while the aspen and birch mixed forest types mature at 50-60 years. In Duluth, despite the dominance of aspen / birch, one can find "older growth" forests in most of the city forest parks. Notably, Lester Park has some 150 year old white pine and Magney Snively Park has good populations of old yellow birch, oak, and even some upland cedar, which is rare for this part of the state.