Photos by Howard Nuernberger
Source: James Sellmer
On September 28, 2005, the first official tree in the future botanic gardens was dedicated to the Arboretum in honor of Dr. Charles L. Hosler, senior vice president for research and dean emeritus of the graduate school and professor emeritus of meteorology, and in memory of Dr. Hosler's late wife, Anna Rosa Hosler. The tree, a white oak (Quercus alba) is a gift from George Biemesderfer, a Penn State alumnus in agriculture, who wanted not only to commemorate his cousin and mentor, Dr. Hosler, and his wife, but also to inspire others to help build the Arboretum. In Mr. Biemesderder's words, “The white oak is a big tree. But really, it’s small in respect to the whole project.”
Having been planted near the ridge in the middle of the Mitchell Tract, the Hosler Oak faces Park Avenue (the main entrance to campus from the Mt. Nittany Expressway/future Interstate 99). It will eventually grow to be 80 to 100 feet tall with a trunk 3 to 4 feet in diameter and a spreading crown form typically seen on old, open-grown white oaks in the central Pennsylvania countryside. This will be the Arboretum's "witness tree," a living cornerstone that will witness the full development of the Arboretum. A century from now, this tree will be a prominent feature of the Arboretum landscape and a venerable reminder of its origin.
As the Arboretum receives donations, the 56-acre tract surrounding the witness tree will be filled with demonstration and specialty gardens, a conservatory, an education center, and features such as a pond and fountain, event lawn, overlook pavilion, and parterre garden (as illustrated in the watercolor rendering below).
On March 21, 2005, the tree was transplanted from Green Acres Nursery (owned by Mr. Biemesderfer) in Lititz, Pennsylvania, to the grounds of the future Arboretum at Penn State just north of the University Park campus. The tree, which is 35 to 40 years old, has a 14-inch diameter a foot above the ground, and is 33 feet tall.
A tree this large required extensive preparations for transplanting. Those preparations began in November 2001 when extensive trenching was done around the tree in the nursery to encourage root development. Dr. James Sellmer, associate professor of ornamental horticulture, worked with Mr. Biemesderfer's crew to oversee and document the tree's root development and the move from the nursery in Lancaster County to Centre County.
Two days were required for digging and preparing the tree to be transplanted. When it was lifted by a 50-ton crane from the ground, the entire tree and its 9-foot root ball weighed approximately 14 tons, making it the largest tree transplanted onto Penn State property since at least 1933, when two large elms were planted at the front corners of Old Main.
On the historic spring afternoon when the Hosler Oak was brought to Penn State, Dr. Hosler, Mr. Biemesderfer, and Dr. Steiner were joined in the Mitchell Tract by several Penn State administrators, all of whom tossed a ceremonial shovel of soil into the trench around the root ball.
Caring for the Hosler Oak
Dr. Sellmer anticipated that the large tree would be susceptible to moisture stress during its first season in the Arboretum because of its limited root system and the well-drained site where it had been planted. He provided soil probes for Penn State's tree crew, headed by Jeffrey Dice, and the crew from Green Acres Nursery to insert into the soil of the oak's root ball before the planting hole was backfilled. Attached to the probes were sensors, embedded at various depths in the soil.
Moisture probes reveal the relative moisture content of soil through time by measuring electrical conductivity of the soil. High soil moisture enhances conductivity. Dave Despot, research support assistant in the Department of Horticulture, used the sensor readings and measurements of the tree's pre-dawn leaf water potentials (a direct measure of plant water status) to guide him in knowing when to activate a drip irrigation system around the tree.
Taking these precautions turned out to be quite fortunate because hot weather arrived early. There were five days during which the heat exceeded 90 degrees in June alone, a month in which the State College area averages 1.8 days above 90 degrees in a 75-year cycle.
Because the 2005 season continued to be dry and hot, it was necessary to monitor the oak several times a week, and to provide 58 inches of water to the tree's roots from March through September.
At the end of August, Dr. Sellmer reported that the watering had not only enabled the oak to survive, but to begin extending its root system into the mulched area beyond the root ball. Monitoring will continue in 2006.
Other Trees at Penn State
An inventory of the more than 12,433 trees on the University Park campus was begun in 2002. You may read about and view the 2,273 that have been inventoried so far, including heritage trees and commemorative trees, on the Trees of Penn State Web site.