Practical Silviculture
The German Way to Cultivating Specimen Oaks
By Maxwell McCormack
The first recorded use of timber in Maine was the 1608 launching of the pinnace Virginia of Sagadahoc at the Popham Colony, when oak was as important for building ships as the better-known pine masts reserved for the king’s Navy. Forestry as a science and practice, however, was late to arrive and slow to develop in the U.S. Dr. B. E. Fernow, a Prussian, was recognized in 1876 as the first technical forester in America. The German influence was strong during the early years when Dr. C. A. Schenck established the Biltmore Forest School at George Vanderbilt’s Estate near Asheville, NC in 1898. Gifford Pinchot from Connecticut, a Yale graduate, studied forestry in Germany and France and subsequently was appointed chief of the newly established U.S. Forest Service in 1905. In 1903, the forestry curriculum at the University of Maine was established -- one of the oldest baccalaureate forestry programs in the nation.
Twenty years later, two iconic forest commissioners of Maine; Albert Nutting (UM ’27) and Austin Wilkins (UM ’26) were earning their degrees. From then on, freshmen forestry students at Orono were introduced to classic German silviculture and the case history of long-rotation production of oak veneer logs. The illustrations of uniformed foresters standing by massive logs of clear oak displayed for their sale by auction (see photo) captured the fancy of aspiring young foresters.
The science of forestry had been well established in Germany by the late 1800s and provided a foundation for developing principles and practices in America. Keep in mind that some care should be exercised in relating German silviculture to our conditions. The European forests are relatively simple and have fewer tree species There are differences in growing conditions. Look at a world map and trace the 45th parallel north of Bangor over the Atlantic to Europe. Your line almost intersects Bordeaux in southern France. Most of the forests that we study in European silviculture are further north than Bangor. Nevertheless, many lessons have been learned from the long periods of silviculture in European forests.
During my tenure with the forestry faculty in Göttingen, Germany in 1973 I had my first opportunity to visit the oak culture in the Spessart. It was in April, an ideal time, because the harvested logs were numbered and meticulously displayed in roadside locations for review by the prospective buyers. Later, the logs would be sold, one-by-one, at auction.
The Spessart Region is in the northwestern corner of Bavaria, between Frankfurt and Würzburg, and bounded on three sides by the Main River. A long history of oak culture has been documented there. The principal species for veneer production is sessile oak (Quercus petraea Liebl.) growing on south-facing slopes with sandy loam soils. Slow growth (more than 10 rings per inch) of uniform ring width is desired, with a preference for most growth to be as early wood, rather than the more dense late wood, in the interest of better veneer slicing.
From the year 800 to 1803, the bishops of Mainz managed the forests primarily for game. Oak mast was good support for the wild pig populations. Timber was a byproduct. For example, from 1605-14 large quantities of timber were harvested for construction of the castle at Aschaffenburg. During the Thirty Years War, 1618-48, there was much burning across the region favoring the thick-barked oaks and significantly reducing the beech. Good acorn crops through the mid-1660s assured the dominance by oaks. Thinnings were carried out in the mid-1700s. From 1840-70 beech, well-suited for the shady forest floor conditions, was planted to enhance the understory that was important for culturing clear stem lengths in the oak overstory. In 1951, an intensive inventory was conducted with marking of crop trees among the large, overstory oaks. Selections of the best crop trees also formed a basis for genetic improvement of future oak regeneration.
Over time, intensive regeneration and stand-tending practices have developed. Direct seeding has been used, with a variety of moderate site preparations and overstory shelter. For example, a typical site would have been direct-seeded with as many as 90,000 acorns per acre, along with a scattering of other species, for oak stem improvement and site maintenance. An example of stocking for a 20-year-old stand is shown in the table.
At this point, it’s an extremely overstocked stand, but is an intentional intervention in the interest of having a good selection of final crop trees. In an uncultured situation, the oaks would be short-boled with spreading, coarse crowns. As the young stands develop the potential crop trees exhibit themselves prominently (see photo), but sometimes early cleaning is necessary. Frequent thinnings are employed until there are 160 crop trees per acre. The objective at age 250 is to have 50 to 60 crop trees per acre in the dominant stands. Care must be taken to keep the understory beech under control since beechnut production can result in excessive quantities of stems. The presence of old-age stand remnants and specimen trees (see photo) has provided additional information and understanding of long-term growth dynamics.
Harvesting is done by experienced workers who buck the logs very carefully for best value. They’re able to capitalize on the relatively short, marketable lengths (five to six feet) of veneer logs. Multiple logs from the same tree remain grouped throughout the sale period. This brings better value to upper logs because buyers can match color and grain. Each log is prepared for individual display, raised on blocks, and numbered for sale. Potential defects are cut out for examination, and a strip of bark is removed at the midpoint of each log to show bark thickness. At the ends of each log a chainsaw cut through the bark forms a gutter to deflect rainfall flow away from the radial faces.
The principles and practices illustrated by the German sessile oak case histories provide a guide for pro-active silviculture approaches for establishing long rotation, high-value oak in suitable Maine woodlots. Our red oak (Quercus rubra L.) could be cultured in mixed stands, or patches, with rotations of 80- 120 years, depending on site characteristics and intensity of the silviculture. In future articles, some specific considerations for Maine woodlots will be discussed.
(The author’s 1973 tenure in Germany was supported by a Humboldt Prize awarded to senior American scholars in gratitude for the Marshall Plan and its s support for the recovery of Germany after World War II.)
Maine Woodland Owners member Max McCormack is research professor emeritus at the University of Maine. E-mail him at: mlm2@uninets.net