There are upland forests scattered throughout the Upper and Lower Arb. All of these forests have been disturbed to some degree, and many are only a few decades old. During the early 20th century, the area of forest in the Arb was much less than today. The most mature upland forest is Best Woods in the Lower Arb and the oldest upland forest restoration is Stork Forest along the paved trail in the Upper Arb. Until recent changes in land use, the upland forests were highly fragmented and shaped in such a way that they were plagued by edge effects. The highest priorities for upland forest management have been to increase total forest area and to decrease the amount of edge habitat, thereby producing habitat for forest plants and animals that benefit from larger blocks of forest known as “interior forest”.
A large block of upland forest is taking shape in the northeast portion of the Lower Arb, and eventually, there will be about 180 acres (73 hectares) of contiguous forest in that area alone. There will be an additional area of at least 50 acres (20 hectares) of upland forest in the southeast corner of the Upper Arb. Some of these forests will grow by means of natural colonization of abandoned agricultural fields by trees. However, the forest-building process can be significantly accelerated by hand planting of tree seedlings, and this is being done in select areas. Types native to Minnesota are used, typically from seed collected from the local area to maintain genetic similarity to nearby forests. In the Upper Arb, forest planting has been concentrated in the Alumni Field. This field was removed from agriculture in 1986, and trees have been planted here over multiple decades starting in 1990. Alumni and student volunteers have done substantial amounts of the tree planting here. Many thousands of trees have been planted in former agricultural fields in the Lower Arb as well. Once trees are large enough to create shade woodland wildflowers, sedges and grasses are introduced.
Planted trees planted suffer very high mortality without some further intervention. Competition with other plants, especially grasses, can be intense; this is prevented by placing mulch mats around the small trees to prevent growth of potential competitors. Browsing by deer (Odocoileus virginiana) and rodents (especially voles, Microtus spp.) can kill young trees, and most are protected by “sleeving” with plastic tubes until the trees are large enough to resist herbivores. Additionally, the growing tip, once tall enough to reach outside the tube, is protected with a paper bag or cap in the winter to ward against hungry deer. A few areas have been fenced to prohibit deer incursion.
- To learn more about tree identification in the Upland Forest, check out the Upland Tree Guide.
- For plant species found in the Carleton Upland Forests, check out the Upland Forest Plant List Page.