The Changing Forest on Mt. Nittany

By Tom Smyth, MNC Board member, November 2008

On a recent sunny Sunday afternoon cars were parked down around the bend on ML Nittany Road and the trails were filled with hikers. As I headed up the Hal White Trail the folks coming down seemed happy and several remarked on what a beautiful hike it is and how good the trails are. And, they were right. That got me to thinking about how different the hike was when I first went up in 1955 as a young faculty member, an advisor to the Penn State Outing Club (PSOC). Then, the only trails were apparently old logging chutes that came steeply down the fall line. The mountain had been clear cut early in the 20th century so the forest consisted of saplings and small pole timber, mostly sprouts from old stumps, and some seedlings that had been released by the lumbering. There was a very small view at what has since been named the Mike Lynch Overlook. The hike provided a good physical workout; we climbed Mt. Nittany “because it is there”, not for the beauty of the forest or excellent views.

Over the next several years, with help from some PSOC members we added a loop trail on top (now blazed white) partly following old logging tracks, and cleared several more outlooks. In the late 1970s Tom Thwaites and Steve McGuire made the diagonal Hal White Trail, since modified by additional switchbacks. The blue trails and outlooks have been added since the early 1990s. Diagonal trails have made the ascent less arduous and reduced trail erosion. The additional viewpoints have made the hike more rewarding.

Meanwhile, the forest itself has been maturing and changing. Sprouts from decaying stumps following lumbering often become trees with rotten cores and a reduced life span. Many have died, providing an opportunity for the survivors to grow larger. Helpful thinning has also been provided by several other agents. In 1955 one of my first assignments was to attend a conference in Carlisle on oak wilt, a fungus disease mainly spread by leaf hoppers, possibly by woodpeckers, and through root grafts. Affected trees may die within a month or survive up to a year. Oak wilt killed some trees. The next plague was extensive defoliation by oak leaf roller caterpillars. There was some tree mortality directly due to recurring extensive defoliation and more due to “oak decline”, a loss of vitality abetted by air pollution, leaving the trees more susceptible to secondary attack by other insects and pathogens. Over the recent decades gypsy moth populations have increased to damaging levels twice and have been controlled by aerial spraying, once with a chemical (Dimilin) and recently with a bacterial spray. Again there was some tree mortality.

More thinning has been caused by other agents. Lightning strikes are common on or near the ridge. Heavy snow or ice burdens and freak winds have brought down a few trees. Trail compaction by hikers weakens nearby trees. Campfires scorch the surrounding forest. A few trees have been cut to block eroding older trails or provide logs for water bars and benches. I can recall five surface fires that cleared out underbrush but harmed few of the larger trees. Where trees die, surrounding trees are able to grow more vigorously. There is also an opportunity for new trees to have a chance. What these new trees are depends on what seeds are present and on environmental conditions, especially the soil and water.

Most of the mountains of the ridge-and-valley province, including most of Mt. Nittany, are capped with white Tuscarora sandstone (or quartzite). This breaks down to a white sand which easily washes away. It is quite acid, drains rapidly and is unable to bind more than a minimal amount of plant nutrients. Most of the useful nutrients on the ridges are contained within the vegetation, especially the bark of trees. Thus, harvesting the trees impoverishes the soil. The trees best able to survive on these ridges are chestnut oaks which an tolerate poor acid soil, dry summers and exposure to the winds. Their thick bark resists surface fires. Another tree that withstands these conditions is pitch pine, but there is very little pitch pine on the southwest end of Mt. Nittany. However, there are numerous table mountain pines, a southern species found here at the extreme northern limit of its range. Just below the ridge there are black and paper birches and red maples. The ground is covered with lowbush blueberries and teaberry. The fragrant pink flowers of trailing arbutus are a bonus in late April.

At the southwest end of the mountain the ridge is a little lower and is topped by the older Bald Eagle sandstone. This brown sandstone is softer and apparently contains more plant nutrients because the forest is more diverse. It must have supported a forest of American chestnut before the lumbering. The chestnuts were killed to the ground by chestnut blight early in the 20th century but the roots survive and continue to send up shoots There are many young chestnuts even today, but they don’t grow to a trunk diameter of more than three or four inches before the blight attacks and kills them back to the ground. The forest on this end of the ridge today contains many pignut hickories, red oaks, black cherries, service berries and small sassafras trees. Pink azaleas provide a fragrant display in mid-May. Teaberry is very abundant

Lower on the slopes where the soil is deeper and moister there are many more red and black oaks which eventually overtop the chestnut oaks and they grow larger where the bedrock is mainly shale. Still lower, near the parking area and lower boundary of Lion’s Paw land the soil is deeper, richer and moister. White oak, white ash, shagbark hickory and black maple are common trees; witch hazel and viburnums are common shrubs; anemones, violets and saxifrages and some of the woodland goldenrods are among the ground cover plants. Wild grape and Virginia creeper, formerly rare, are becoming more common and can be expected to provide food for wildlife in the future.

The broad top of the mountain is level to somewhat dish shaped. Secondary soils have developed in places. White oak, white pine, black birch, black cherry and hickory are growing to larger size and are increasing in numbers. Where there is enough light blackberry, huckleberry, lowbush blueberry, and deerberry are more likely to bear fruit here than elsewhere on the mountain. This is where one is most likely to see wild turkey and grouse.

The forest today is becoming mature, with some large trees providing a canopy above smaller species or younger trees, large shrubs, small shrubs and ground cover plants. Some vines are present Chestnut oak will continue to dominate the crest of the ridge, but is being replaced mainly by other oaks farther down. From the progression of sizes of seedling to sapling trees, it appears that white ash and shagbark hickory are spreading up the mountain and pignut hickory out and down from the southwest top. White pine has increased on the flat top. The forest is still not old enough to provide many den trees for wildlife, but should soon reach that stage Without fire, pitch and table mountain pine should continue to die out without much replacement.

In summary, the forest on the mountain has become more interesting and attractive over the years and the trails are more hiker friendly. Visitors to the mountain are appreciative.