Plummer’s Hollow Nature Trail
This is the text to a self-guided walking tour up the hollow road offered until recently at a signboard at the bottom. The numbered paragraphs used to correspond to numbered signposts constructed by Jeff Scott, a hunter in Plummer’s Hollow. However, those signposts were virtually all destroyed by vandals this summer, however, so we have stopped circulating the brochure except here. We hope to produce some sort of replacement this spring.
Text by Bruce Bonta with the assistance of Mark Bonta, who supplied the non-sequitor tree identification notes at the end of each paragraph.
Welcome to the Plummer’s Hollow Private Nature Reserve, a 640-acre privately-owned forest dedicated to nature study and environmental education. This 1.2 mile nature trail begins at the gate and follows the Plummer’s Hollow Run up the road almost to the houses at the top of the hollow. We have two goals for this nature trail. One is to describe some of the natural features in the hollow and to point out the natural processes that take place here. The second is to explain some of the human activities that have taken place in the hollow and the ways that they have affected the natural environment. Natural processes and human activities are present everywhere, but it is our goal to minimize the impact of humanity here so that the plant and animal life can flourish as much as possible. We will describe the ways we interact with nature in this brochure. As you walk up the road you will find numbered paragraphs in the brochure that correspond with the numbered markers on the left side of the road. We hope you will enjoy the birds, animals, plants, and peace, and we trust that you will not disturb anything during your walk.
The human history of Plummer’s Hollow begins at the entrance gate. Many years ago five houses were located in the flat area near the gate, one to the left and four to the right as you face the hollow. These homes, gone now except for a few cellar holes, were the last remaining buildings of Upper Tyrone Forge, which was built at the entrance to the hollow in 1813. This settlement was part of an iron-making community that also included Tyrone Forge and Ironsville, villages that still exist to the southeast at the edge of Sinking Valley. All three villages were developed about 40 years before the town of Tyrone. The iron industry based here required large amounts of forest to be clearcut each year to supply the charcoal for the forges, and it appears as if the forest in the hollow was first cleared around 1813 and again in the 1840s. This devastation was normal at that time, but over the following 150 years the human owners of the land have gradually changed their approaches to forest management. The present owners value the forest primarily for its own long-term worth–the needs of the wildlife and plants are very important–but compromises are made that allow us to live here too. Please proceed about 250 feet up the road to the first stop.
1 This is a good spot to examine the basic geological structure of Plummer’s Hollow. The dark red rock outcropping on the right side of the road is an exposure of what geologists call the Juniata Formation, the uppermost (newest) formation in the Ordovician System of rocks which date from about 360 million years ago. The ridge to the left, Laurel Ridge, is composed of the next older formation in the Ordovician, the Bald Eagle sandstone. Sapsucker Ridge to the right is composed of rocks that are newer than the Juniata. The rock formation at the top of the ridge is the Tuscarora Quartzite in the Silurian System. The two ridges are formed by relatively harder rocks that resist erosion better than the Juniata formation, a somewhat softer, fine-grained sandstone which has no fossil remains. While the Bald Eagle and the Tuscarora formations along Bald Eagle mountain to the northeast toward Williamsport and along Brush Mountain to the southwest toward Hollidaysburg are characterized by many miles of rocky forest land, the Juniata formation weathers into a fairly deep, rich red soil good for pastures and fruit farms. The apple farm at the top of this hollow that Mr. Plummer began in 1850 was a good example of this; the Way Fruit Farm on the top of Bald Eagle Mountain between Port Matilda and Marengo is another. This softer rock, the Juniata sandstone, also allowed a 1.5 mile long stream to develop between the two ridges and form Plummer’s Hollow. The tree on the left next to the old retaining wall is a black birch.
2 Look to the left on the far side of the stream, where several large, rectangular stone blocks are visible in the circular area that is about 20 feet across. These blocks mark the remains of a cistern that was built in 1850 by the Pennsylvania Railroad to supply water for the steam locomotives using the new railroad line between Philadelphia and Pittsburgh. The first person appointed to be in charge of the water station was William Plummer, after whom this hollow is named. Mr. Plummer had worked as a forgeman at the Upper Tyrone Forge and he had lived with his family in one of the houses owned by the iron company. He bought the original 55 acre farm at the top of the hollow in 1850 when he quit his job at the forge and began to work for the railroad. The water station was washed away in the flood of 1936 except for the few blocks that remain.
3 One of the basic facts of life in the hollow is the instability of the mountainside soil. In the 1970s, geologists from Penn State studied and mapped a number of fracture traces and lineaments in the hollow, faults in the underlying rock structures which tend to conduct water and cause slope instability, rapid runoff, and earth slide conditions. Normally they are hard to detect except through satellite imagery, but the evidence of one of them can be seen right here. The bank on the right side of the road is devoid of vegetation most of the time because of the constant sliding of soil at this point. Also, several trees on the upper side of the road in this area and further up the hollow curve dramatically just above ground level. The reason for this curving is that the tap roots go down far enough into the subsoil and rocks that they are anchored in place, but the constant creep down the steep mountain slopes of the upper few feet of soil bends the trees, which continue to grow straight up. Human activities that disturb the natural anchoring action of the trees–such as lumbering or the building of a road such as this–may speed up the normally slow creeping of the surface soil. Rapid erosion and even landslides can result. Notice the large, twin cucumber trees about four feet apart next to the stream.
4 Note the fading sounds of civilization as you round the bend and climb further into the hollow. Necessary as the highway and railroad tracks are, it is refreshing to escape the noises of modern transportation. The hemlock-beech-rhododendron forest community, through which you will walk for the next half-mile or so, is one of the outstanding natural features of this hollow. Much of northern Pennsylvania, which is colder than Blair County, was blanketed by this kind of forest before it was clearcut in the late 19th century. Plummer’s Hollow is colder than the surrounding forests because it faces northeast, so it supports the more northerly type of forest. While we rarely receive as much cold and snow as places further to the north, during the record-breaking winter of 1993-1994 the snow and ice frequently slid in small avalanches down the slope of Laurel Ridge, burying the stream. The paint line on the small oak tree across the stream shows the level of accumulated sleet, snow, and ice in early March, 1994–14 feet 6 inches above the stream. The large tree near the stream below this marker is a basswood.
5 One of the primary goals of the Plummer’s Hollow Private Nature Reserve is to meet our basic needs and the needs of our friends and family members who visit us, while maintaining the natural environment in as pristine a state as possible. The goal is well illustrated by this stop. While the road dates back at least to the time of William Plummer, we have to continue to maintain it in order to live at the top of the hollow. Therefore, in 1997 we excavated the pulloff on the right. The other five pulloffs farther up the hollow are about 800 feet apart, but the distance from the entrance gate to what is now the second pulloff (ahead and on the left) is over 1500 feet. Meeting an oncoming vehicle in this area required one of the vehicles to back up several hundred yards. With this new pulloff, passing throughout the hollow is now a simple matter of backing only a short distance to allow the other car or truck to pass. A two-lane road would destroy far too much forest and is out of the question–the six pulloffs serve our purposes quite well now. The patch of rhododendron above the stream is framed by two tulip trees.
6 In July 1981 a tornado, or downburst, leveled almost two acres of trees across the stream to the left. Only the hemlocks survived. Some of the rotting trunks can still be seen beneath the sprouting growth of young trees. It is interesting to watch the regeneration of a natural blowdown in comparison with the regeneration from the various forest tracts that were lumbered previous to our buying them. In this blowdown area the tallest trees with the long, feathery leaves, are Ailanthus, a non-native, invasive species. We presume that after another hundred years the native trees will mature and crowd out the rapidly-growing pioneer species.
7 We installed the 24-inch culvert pipe and began excavating ditches along the road in 1997 in order to keep water from flowing in and across the road. The small ravine coming off the mountain to the right produces a lot of runoff in floods, several of which have nearly destroyed the road. The culvert pipe should alleviate that problem. Not only does water erode the road in the warm months, it causes difficult driving conditions in the winter due to the buildup of ice. Since 1995 we have put over 1,000 tons of stones and gravel on the road, which has helped the driving and reduced siltation and sedimentation in the stream. Before 1995 the stream ran brown after every heavy rain, but now it remains mostly clear. We plan additional improvements on the road to give us better access and to keep the stream as pure as possible at all times.
8 A wet, 24-inch snow storm in December 1992 brought down about 100 trees across the road. In addition to the extensive labor needed to reopen the road, the natural disaster seemed to spell the end of the deep shade environment of the hollow, which had already been buffeted by a 1991/92 clearcut farther up on Sapsucker Ridge to the right. Except for clearing the road we left the trees where they fell, and were rewarded by two pairs of winter wrens nesting for the first time in the hollow that following summer. These diminutive lovers of deep, northern forests are fairly scarce breeding birds in Pennsylvania, and they evidently needed the fallen trees to make them feel at home here. Their glorious songs punctuated the hollow for months, and we quickly learned to ignore the increased light levels in the hollow. A natural disaster turned into a natural discovery. The large evergreen trees that shade this area are all hemlocks.
9 Former owners installed three large grates such as this one and 40 of the smaller ones in the early 1950s. These unique drainage structures are relatively easy to clean out and to maintain. The shrubs next to the stream are witch hazels.
10 Except in a very dry summer, the babble of the stream is one of the most relaxing natural sounds in the hollow. The Plummer’s Hollow Run has a high biotic index–a large number of different aquatic invertebrates live in it–and it has a Ph of 6.5. Compared to other streams in this area, with their loads of industrial pollution, human waste, agricultural runoff, and, to the west of Tyrone, acid mine drainage, this stream represents an increasingly scarce and important resource. The large tree to the left is a beech, surrounded by a number of root clones–“sons of beeches.”
11 From various clues we estimate that the large white pine to your right is over 125 years old. While large old trees are impressive and add beauty to a woods, a healthy Pennsylvania forest, much like a human community, is a mixture of trees both old and young, large and small. Landowners and foresters frequently clearcut Pennsylvania woodlands in the mistaken belief that the resulting even-age forest is natural, much like a large natural blowdown. However, except for the two-acre blowdown you already saw, all of the trees on this property have either fallen due to mortality from disease or injury, or they have come down here and there in ice and snow storms. From our observations, we conclude that a large-scale natural disaster, such as a 10-acre blowdown, would be an extremely unusual event in this part of the state. A clearcut, or one of the variants used by foresters such as a shelterwood cut, does not imitate nature, and can only be justified by economic expediency. The small tree 10 feet to the left is a Hercules club.
12 Notice the black layer of charcoal on the right hand bank of the road. In about 1813 this flat area was leveled off to form a charcoal hearth, one of many places in the hollow and the surrounding ridges where colliers employed by the Tyrone Iron Company piled up log billets into dome-shaped mounds, covered them with earth, and slowly burned them down into charcoal. The charcoal was then hauled down to be used for the forge fires. If you wish, stick your fingers into the charcoal and feel a small amount of it. Notice the fine white oak tree on the right-hand edge of the charcoal flat.
13 Sometimes nature takes a whack back at us and our efforts to control the natural process of water drainage from the road. In 1993 a white pine on the other side of the stream fell across the road and hit the large steel grate so hard that it bent down the left-hand end. The rotting trunk is still easily visible, and when it is gone the large mound of earth pulled up by the roots of the tree and the pit just above it where the roots came out will be visible for many centuries. Formations such as this, usually referred to as “pit/mounds” by scientists, are caused whenever trees fall over naturally (locally, they are often referred to as “Indian graves”). Pit/mounds are important because they create micro-habitat mixing zones of subsoil with topsoil. Scientists have found that these spots where the subsoil is mixed with the topsoil due to the ripping out of large root-balls are important for the forest ecology because they tend to produce patches of rich herbaceous understory plants on the forest floor. The saplings on both sides of the road are white ash trees.
14 Look upslope to the right to see the lumbering job, a virtual clearcut which devastated over 100 acres of the hollow in 1991-1992 before we were able to buy the property. It was probably the fourth clearcut on this section of the hollow. In addition to the two cuttings for charcoal in the early 19th century, the forest was cut between 1900 and 1902 in order to pay the owner’s county taxes. It was bought by a lumberman in 1987 who directed a lumbering operation in the autumn and winter of 1991-92 that left only small and misshapen trees. While soil erosion after the clearcut caused a lot of siltation in the Plummer’s Hollow Run, the most serious long-term effect of the clearcut has been the excessive runoff during periods of heavy rain. As a result, every moderately-heavy rain since 1992 has caused extensive erosion of the stream banks along the lower portion of the hollow. The domestic cherry to the left has probably been seeded here by a bird. This species is short-lived in the wild because it cannot compete in a forest. A large sugar maple is up the slope to the right. The large holes in the oak tree above the stream were probably made by pileated woodpeckers.
15 Notice how this part of the forest differs from the lower section of the hollow, a hemlock-beech forest with an understory of rhododendron. Here we see a variety of other deciduous trees with an understory of spicebushes and striped maples. On the left side of the road a red maple grows next to the number sign with a black birch just five feet to the right. A black cherry, the largest tree toward the stream, is visible between the maple and the birch. Above the road on the right are several red oaks and some chestnut oaks (also called rock oaks) with deeply-furrowed bark. The striped maple trees are easily identified by their gray-green bark and vertical white stripes. The gray-barked shrubs to the left are spicebushes. Squeeze the red berries in the autumn, or scrape your fingernails over the twigs the rest of the year to smell the allspice odor. The major reason for the change in forest composition is that the hollow is not so steep here so it receives more sunshine and thus is warmer.
16 The two large stumps that are easily visible about 50 feet above the stream on Laurel Ridge to the left were positively identified by the lab at the PA Bureau of Forestry as white pines. These old pine stumps probably date from one of the early cuttings in the hollow–either the first one of 1813-1815 or the second of the 1840s. The upper, larger, stump is nearly three feet across, and it consists only of slivers from the heartwood of the original tree. A careful examination of the remaining rings indicates that the tree probably sprouted in the early 1600s. The bigger stump is directly on the apex of a large mound formed by the natural falling of an earlier tree. The associated pit, where the roots were ripped out of the ground, is just up-slope from the mound and is hard to see from the road. The giant tree that fell down across the stream nearly 400 years ago was probably many hundreds of years old when it fell. Studying clues such as this about the history of trees helps us to understand the natural evolution of a forest.
17 This is the last stop in the nature trail. Since our houses are just ahead, we hope that you will respect our privacy by turning around at this point. A number of small white pine seedlings have started growing in this area, seeded by the nearby mature pine trees. Before 1991 excessive numbers of white-tailed deer devoured most of the tree seedlings in the hollow. We discovered that the large number of hunters in the hollow were driving many deer around, but they were not taking enough to preserve a healthy ecosystem. The deer did as much damage to the forest as they do to neighboring farmers’ crops. Since 1991 we have restricted hunting to a small group of friends, excellent hunters who know the land well and nearly always fill their tags during hunting season. Their successes help us keep the deer population under better control. As a result the number of deer has dropped to a more normal level, allowing more seedlings to mature than over the previous 20 years. Only the regeneration of young trees will maintain a healthy forest, as old trees mature and die.
As you walk back down the road, we invite you to compare the condition of the stream banks in the upper part of the hollow, where the stream has carved out only slight amounts of soil, with the stream banks across from stops 1 and 2 at the bottom of the hollow. There you will see areas where floods since the 1992 lumbering have gouged out excessive amounts of earth. While stream bank erosion is a natural process, the clearcut continues to have an effect on the stream many years later. We hope that you have enjoyed your walk up the road and this brief introduction to the history and nature of Plummer’s Hollow. We also hope that you understand our vision of a forest that is lightly managed. We believe that wise land use consists of having a healthy curiosity for the processes of nature, protecting the land so that it can heal itself from past abuses, learning from natural events, and enjoying the beauty of the forest as often as possible.