The wooded bluff, located directly to the north of Allison Mansion and running east to west along the entire south edge of the Ecolab, is the most prominent topographical feature. This area has been greatly affected by the many plantings and the disposal of fill dirt (Tungesvick 2003).
The bluff consists of the Hennepin Series soil, which is deep and well drained. The soil in this area is low in organic matter, has a high moisture capacity with moderate permeability, and rapid to very rapid runoff. Specifically, the soil is considered to be Hennepin fine loam soil, which is extremely prone to erosion (Sturm & Gilbert, 1979). The sunlight on the bluff ranges from light shade to deep shade depending on the canopy coverage.
Historically, the wooded bluffs probably contained mesic beech-maple on the lower and middle portions. The likely canopy dominant of the forest were Sugar Maple (Acer saccharum) and American Beech (Fagus grandiflora). A mix of sedge meadow vegetation and wet tolerant shrubs possibly inhabited the seeps along the western half of the base of the bluff (Tungesvick, 2003). The drier, upper portions of the bluff may have contained components of an Oak-Hickory forest: White Oak (Quercus alba), Northern Red Oak (Quercus rubra), and Bitternut Hickory (Carya cordiformis) (Tungesvick, 2003). However, when the settlers came through all but a few specimen trees were cleared for agricultural purposes. Some of the plant species Jensen planted on the bluff include: Hard Maples, Red Oak, Redbud, Sumac, Hawthorn, Elderberry, Indian Currant, Canoe Birch, Witchazel, Crabapple, and roses. However, over the years exotic took over the area and prohibited recruitment (the growth of new seedlings) of many of these native species planted by Jensen.
Common tree species that currently inhabit the bluff area include: Sugar Maple (Acer saccharum), Basswood (Tillia americana), White Ash (Fraxinus americana), Black Walnut (Juglans nigra), and Hackberry (Celtis occidentalis) (Tungesvick, 2003). Non-native species have been dominant in the shrub layer of this bluff; however, current restoration has reduced these populations. Amur Honeysuckle sub-canopy was nearly continuous until 2001 when it was partially removed. Other non-native shrubs that are found in this area include: Privet (Ligustrum vulgare); Common Buckthorn (Rhamnus cathartica), and the vine Oriental Bittersweet (Celastrus orbiculatus). Natives shrubs include Wild Hydrangea (Hydrangea arborescens), Elderberry (Sambucus canadensis), Greenbrier (Smilax rotundifolia), Riverbank Grape (Vitis riparia), and Frost Grape (Vitis vulpia) (Tungesvick, 2003).
Many restoration projects have been done in the Ecolab that had an impact on the wooded bluff including: invasive plant removal, native grass seeding including native Rye and Beak Grass, and planting of tree whips suck as Black Maple, American Plum, Elderberry, and others. The invasive plant removal included Honeysuckles, Buckthorn, Oriental Bittersweet, European Cranberry, Hedge Privet, Burning Bush, Multiflora Rose, Tree of Heaven, and Porcelain Berry. These species were initially removed from January to July in 2001 and they were removed principally along the bluff by basal bark treatment with triclopyr and cut stump treatment with 20 percent triclopyr in oil. The native grass seeding was done on the entire property during the spring of 2001. The grasses planted on the bluff were 1 oz. per acre of Beak Grass and 5 Lbs. per acre of Canada Wild Rye. The planting of tree whips was done in April of 2000; the trees planted were 200 Elderberry and 200 Spicebush (Benson, 2003).
Out of the 85 different plant species Tungesvick found on the bluff, 21 were exotic and 64 were natives (Tungesvick, 2003). This means that roughly ¼ of the species found were non-natives. This illustrates just how strongly the exotic are continuing to thrive in the area since Jensen’s plan was completed, despite the recent efforts to discourage them from doing so. Fighting exotic will be a continual problem in the future.