A Field Survey of Woody Species in the Jensen Landscape of the Henry Ford Estate. University of Michigan-Dearborn Gerard Heath Wayne Roper Orin G. Gelderloos (faculty advisor)

Location of University of Michigan-Dearborn and Henry Ford Estate

The Henry Ford Estate is surrounded by a highly urbanized area. To the East are shopping centers and to the West is a golf course and densely populated housing. The presence and preservation of the Henry Ford Estate is significant to native species of plants and animals. Location of University of Michigan-Dearborn and Henry Ford Estate

Ironically, the Estate was commissioned by Henry Ford in 1914 as a way for him to reside in an area removed from the expanding urban landscape and for he and his wife, Clara, to have a place to enjoy their love of nature.

When Henry Ford decided to convert the former farmland to his new estate he commissioned the work of landscape architect Jens Jensen. His designs typically incorporated loose openings such as narrow meadows and paths within dense mesic woodlands. The plan was initiated in 1915 and was completed over the course of several years. Trees in the new landscape were both seed grown and transferred from other sites. Jens Jensen Jensen strongly believed in the ability of native plants and natural landscapes to sustain wildlife and habitat. Native plants are more likely to interact with each other, support native animal species, and be adapted to local environmental conditions (climate, pests, etc).

Jensen's Meadow and the Rose Garden in the middle of the landscape

Aerial Photo of Henry Ford Estate Image courtesy of Google Maps software

Aerial Photo of surveyed area

Trees Prescribed in Jensen's Original Plan > Sugar Maple > Red Maple > American Beech > Blue Beech > White Oak > Red Oak > White Ash > Red Ash > Hophornbeam (Ironwood) > Sycamore > Black Walnut > Basswood (Linden) > Hawthorn (Haw) > Juneberry > Flowering Dogwood > Sourgum > Tamarack > Butternut

Purpose of the Study > To compare the original prescribed vegetation composition of the Jensen landscape with the current vegetation and determine how the Jensen plan has fared for nearly 100 years. > We analyzed the species composition by dominant overstory subdominant overstory, and understory trees by: species, number of stems, and calculated basal area. > What may the future be for the Henry Ford Estate and Jensen's landscape?

Methods >Identify and measure each tree encountered with a diameter breast height (dbh) greater than 1.5 cm or circumference of about 5 cm. Dbh identified at 4 ft. > Record data in the field by species and circumference within each map area >Use circumference to find diameter and estimated basal area of each identified tree >Survey period: September 2011 – December 2011

Results of 2011 field survey 58 species identified 3487 stems counted Dominant Overstory (Trees with dbh >20cm) - Stems Identified:463 - Total basal area:865,546 cmsq Sub-dominant Overstory(Trees with dbh 9.1 cm – 20 cm) - Stems identified447 - Total basal area:66,127 cmsq Understory(Woody vegetation with dbh <9 cm) - Stems Identified: Total basal area:34,166 cmsq

Species Ranked by Total Number of Stems

Jensen Landscape Dominant Overstory Composition (dbh >20 cm) (Ranked by number of stems)

Jensen Landscape Sub-dominant Overstory Composition (dbh 9-20 cm) Ranked by Number of Stems

Jensen Landscape Understory Composition (dbh 9-20 cm) Ranked by Number of Stems

Observations of number of stems The species with the greatest number of stems are part of the understory. - Common buckthorn - American Bladdernut - Honeysuckle - Staghorn Sumac - Witch-Hazel Common Buckthorn has a relatively large number of stems compared to other species in the same area (~ 16% of total and ~ 22% of understory)

Observations of Basal Area The top 5 species contribute to more than 50 percent of the basal area but account for less than 10% of the number of stems in the surveyed landscape. Each of the species with the most basal area are typical of a mature forest in the Michigan region. A few species are prominent in both basal area and number of stems - Boxelder Maple - Black Cherry - Silver Maple

Trees featured in Jensen's original plan FOUND > Sugar Maple > Red Maple > American Beech > Blue Beech > White Oak > Red Oak > White Ash > Red Ash > Hophornbeam (Ironwood) > Sycamore > Black Walnut > Basswood (Linden) > Hawthorn (Haw) > Juneberry > Flowering Dogwood NOT FOUND > Sourgum > Tamarack > Butternut

Why are other prescribed species not present? > Not able to transplant enough trees from surrounding forests at the time > Sourgum and Butternut can be found in other areas throughout the estate, but may have been out-competed in the Jensen landscape. > Tamarack prefers more acidic soil. Not a great competitor in this area.

How did new species get into Jensen Landscape? > Many birds and mammals eat fruits and transfer the seeds to the area > Wind dispersal of seeds > Jensen encouraged ecological succession. New species were going to end up in the area. > Some ornamental species planted since the original landscaping 44 of the identified species are not in Jensen's original plan

Jensen's Plan The species composition of the The Jensen Landscape is mostly consistent with what is expected of a mesic forest. The presence of large hardwood trees like maples, oaks, and elms that prefer moist soil is evidence that Jensen's original plan for native plants to thrive and provide habitat for other species has worked. Although Jensen's plan has lasted for almost a century, forests are not static communities. Forests and meadows can be disturbed by invasive species, pest infestations, human traffic, and other damaging environmental factors. Are there patterns in the inventory data that show any possible trends?

Future of Jensen landscape: Current Understory Species Buckthorn, the infamous invasive species, appears to be populating the forest understory. Along with other weedy growth species like Honeysuckle and American Bladdernut, Buckthorn can take over the forest understory and prevent the reestablishment of larger native species like maples and oaks which are expected to repopulate the forest floor

Birds are eating Buckthorn fruit and spreading the seed throughout the landscape, and there are not any species helping limit Buckthorn population growth. Management of Buckthorn population may have to be done by hand or with the introduction of a biological control to establish a balancing force against Buckthorn dominance of the understory. Future of Jensen landscape: Current Understory Species Seeds found in droppings of American Robin (T. migratorius) and Gray Catbird (D. carolinensis). Research by Julie Craves and Dana Wloch, UM-Dearborn.

While surveying trees there were many stands of American Bladdernut which had not yet reached the 1.5 cm dbh qualification. In the years to come those stands of Bladdernut may become dense enough to crowd out the area and prevent new saplings from growing Mature White Ash trees in the Jensen landscape had previously been decimated by the Emerald Ash Borer (Agrilus planipennis). A foreign pest that is relentless in its attacks. Perhaps the Ash saplings arise after mature Ash trees topple over and create openings for sunlight in the high canopy. Future of Jensen landscape: Current Understory Species

Understory species in the Jensen landscape Nearly a century later Despite the presence of over 130 stems of White Ash, the future of the species in the area is bleak. To learn new ways to prevent Emerald Ash Borer attacks or to prevent Ash saplings from the same fate as mature trees, it is in the best interest of preservation to closely monitor and protect any young Ash trees to help maintain the composition of the mesic forest and meadows that Jensen planned many years ago. Other large tree species like Maple and Oak appear to have healthy mature populations, but their understory populations pale in comparison to other. There is little cause for concern about the older trees, but saplings will need to compete with invasives and weeds.

What should be done? Miraculously, Jensen's native landscape plan has survived through decades of surrounding urbanization, possibly because of the connection to Henry Ford's name and the desire to preserve his legacy. Almost a century later we can confirm that the composition of the landscape is that of a mesic forest. Most of Jensen's initially planted species are present and only a few did not survive to populate the estate grounds. His plan was fulfilled, but could possibly be in danger because of invasive species.

The Heny Ford Estate is one of few natural areas remaining in Southeast Michigan. The reasons to ensure the health and longevity of the area we have inventoried are both ecological and ethical. There is little native habitat remaining to support wild animals and provide a natural buffer against urban activity. What should be done?