A Century of Regrowth: The Little Arnot Photo Series
Forests are constantly growing and changing. They grow from young forest to mature forest and sometimes to old-growth, and the cycle repeats. The US Forest Service has studied forest growth and change here on the Allegheny Plateau since 1923 when both the Allegheny National Forest and the Northeastern Research Station were established.
Each stage of a forest offers different benefits for people, wildlife, and plants – clean water, wood fiber, habitat for wildlife, and outdoor recreation. Like a community, a forest is healthiest and offers the most benefits if it contains a variety of ages and kinds of trees, plants, and animals. When forest management and science work together, we can sustain natural resources to meet our needs today and the needs of our grandchildren’s children, too.
Little Arnot Photo Series
1928
Much of the Allegheny National Forest looked like this when the Forest was established in 1923. This clearcut resulted from the first timber sale on the Allegheny in 1927 and became the first research study area. This open condition allowed great amounts of sunlight to reach the forest floor which encouraged sun-loving plants like blackberries, pin cherry, aspen and yellow poplar to grow rapidly. Young forest habitat is essential for many migratory bird species, including some that nest in mature forest. Right after the young are fledged, they fly to the nearest young forest habitat to find the berries and insects they need to prepare for their long migratory flights, often as far as South America! Deer, turkey, bears, and other wildlife also prefer to have some of this habitat in the forest. The fast growth rate of healthy young forests helps pull carbon out of the atmosphere and helps stabilize soil, supporting the water-filtering role that forests play. Some of the pressure to establish the Allegheny National Forest had come from leaders in Pittsburgh, who hoped that forest regrowth would clear up the muddy water flowing by the Point in downtown Pittsburgh, and as the forest grew, the water began to clear.
1927
This photograph shows the stand prior to final harvest in 1927. This stand had 335 trees per acre. The diameter of the merchantable trees was 14.9 inches, and about half the basal area consisted of American beech. Ten species were measured in this stand, with sugar maple and black cherry representing the second and third most abundant species, respectively. The timber sale was conducted in two parts. This was typical of harvests at that time. First, the merchantable sawtimber was removed during the winter of 1927. Although sawmills and chemical wood factories often shared railroad facilities, their harvests were conducted separately. The sawmill harvest left the residual shown in this photograph. While it is difficult to imagine that it was economical to harvest the widely spaced, small residual trees apparent in this photograph, such double harvests were not unusual where railroad access was available to chemical wood companies.
Then, most of the remaining trees were harvested for use as chemical wood. The chemical wood industry flourished in the Allegheny region from the early 1900's until the early 1940's. Destructive distillation of small hardwood trees was made economical by the ready availability of natural gas and by cooperation with booming sawmill and tanning industries in the same region. In the case of the Little Arnot clearcut, however, about 24 trees per acre were left. The trees that were left had a diameter of 8.4 inches, and consisted of 8 basswood, 12 sugar maples, 3 American beeches, and 1 blue beech trees per acre. The man in the picture is Allegheny Forest Experiment Station employee Birger Berg.
1937
By 1937, some trees that had regenerated in the wake of the harvest disturbance had grown large enough to be tallied (1.0 inches and larger). The new stand was dominated by the shade-intolerant and fast-growing black cherry. Residual trees still dominated the merchantable portion of the stand, holding the diameter of merchantable trees at 8.8 inches, and basswood and sugar maple, each with several residual trees, joined black cherry as the most abundant species in the new stand. There was apparently no regeneration of American beech in the wake of the 1927-28 harvest, for although beech continues to be tallied, it is as one small stem per acre.
1948
Twenty years later, the Little Arnot area was in the poletimber stage. This is a stage of intense competition among the trees, and the canopy the trees create is so dense that the shrubs and wildflowers that grew in the young forest stage have been shaded out. Rapidly growing trees continue to protect soil, soak up carbon, and add lots of oxygen to the atmosphere. The taller trees shade streams, which helps to regulate the water temperatures for fish and other wildlife.
1947
By 1947, the stand had begun to differentiate into crown classes, and the differences in growth rates between the species begin to be apparent. The large trees in the left foreground are 20-year-old black cherry, while a 20-year-old sugar maple sprout clump in the center background is much smaller. There were 497 trees per acre in 1947. About one-third of the stocking was black cherry, with sugar maple and the short-lived pin cherry representing the second and third most abundant species, respectively. The diameter of merchantable trees persisted at 8.9 inches, and there were 12 tree species detected in this tally.
1968
In only forty years, the forest had regained an appearance more familiar to us. Maturing forests like this provide acorns, cherries, and beech nuts for bear, turkey, and other wildlife. Competition between trees is less fierce than it was in the early decades, and filtered sunlight reaching the forest floor allows for the reestablishment of wildflowers like trillium, Canada mayflower, and others. Tall and leafy crowns provide spots for bird nests, and growth is still fast enough to be important for soaking up carbon, stabilizing soil, and filtering potential water pollution. Campers and hikers enjoy the wooded scenery, and we all depend on sustainable supplies of wood for paper and fiberboard.
1947
By 1947, the stand had begun to differentiate into crown classes, and the differences in growth rates between the species begin to be apparent. The large trees in the left foreground are 20-year-old black cherry, while a 20-year-old sugar maple sprout clump in the center background is much smaller. There were 497 trees per acre in 1947. About one-third of the stocking was black cherry, with sugar maple and the short-lived pin cherry representing the second and third most abundant species, respectively. The diameter of merchantable trees persisted at 8.9 inches, and there were 12 tree species detected in this tally.
1958
By 1958, the tree species became quite distinct. The black cherries in the left foreground had the characteristic flaky bark. The stand was fully stocked, with a relative stand density of 102%, and 1,610 trees per acre! Black cherry continued to dominate, representing nearly half of the stocking, followed in order by sugar maple and American hop-hornbeam. Fourteen tree species were tallied in 1958, including one-time appearances by short-lived species like devil's walking stick and serviceberry. Phil Ackerman is seen here for scale.
1968
A photo was taken in 1968, but a tally was not completed until 1972. Self-thinning had reduced the number of trees per acre to 997. Relative density stood at 99%, and the diameter of merchantable trees had reached 9.1 inches. Black cherry, sugar maple, and American hop-hornbeam, in that order, dominated the stand's basal area, with black cherry now representing nearly half of the stocking. Twelve tree species were detected during this inventory.
1998
Look at how much the forest has grown in 70 years! Because so much of the Allegheny Plateau was so heavily cut before 1930, most of the Allegheny National Forest was mature forest by this time. At this stage, the forest can produce the highest value wood products like furniture, cabinetry, flooring, or veneer. Turkey, bear, and other wildlife continue to thrive. People find great enjoyment pursuing a variety of outdoor recreation activities in mature forests. Research continues and is the basis for sustainable management of Allegheny hardwood forests not only on the Allegheny National Forest, but on adjoining public and private forests as well.
1978
In 1978, in the stand had 661 trees per acre. Relative density was 94%, and diameter of merchantable trees was 9.7 inches. Black cherry, sugar maple, and basswood, respectively, dominated the stand's stocking, with black cherry representing over half of the stocking. Pin cherry was completely absent from the stand by this tally, fifty years after disturbance. The faster growth of black cherry is apparent by this time, with the l diameter of merchantable black cherry at 9.4 inches, while sugar maple, still heavily influenced by the residual stems left after the chemical wood harvest, had a merchantable diameter of 8.7 inches.
1988
In 1988, 55%, of the stocking was black cherry. There were 461 trees per acre, of which only 140 were black cherry. Sugar maple, with 282 trees and 32% of the stocking and basswood, with only 11 trees but 8 % of the stocking, are still the second the third most common species, as measured by basal area. The diameter of merchantable cherry trees was 11.5 inches, while sugar maple's was 9.6 inches. Sawtimber volume had begun to accumulate in this stand, which had a net sawtimber volume of 5,300 board feet per acre, of which 3,400 were black cherry. Eleven tree species were detected in this tally, with the addition being a single hickory sapling. A different camera was used for this photo which has caused the trees to look larger than they should in the series.
1998
By 1998 the total number of trees were 346 per acre. Black cherry accounted for 55% of the stocking and 106 of the trees. Sugar maple added 206 trees per acre, and 31% of the stocking. Eight basswood trees per acre contributing 6% of stocking were the third most common species once again, by basal area. Diameters for merchantable cherry and sugar maple were 13.2 and 10.2 inches respectively. The net sawtimber volume increased in the last ten years to 8,032 board feet per acre, of which 5,390 board feet were black cherry. The hickory sapling found in the previous tally did not survive the last ten years, the total number of species found in 1998 was 10.
2018
As the Little Arnot plot passed its 90th birthday, its rate of growth was slowing. Across the Forest, black cherry, the most common species in the Little Arnot forest, was slowing in growth and seed production. Invasive insects, diseases, and plants, changes in air quality, soils, and soil microorganisms all affected the forest. Forest leaders and scientists have joined with stakeholders across the region to form the Allegheny Forest Health Collaborative, sharing resources and knowledge to sustain forest benefits in the face of these challenges.
On the Little Arnot plot, openings in the forest canopy became more common, allowing for an increase in the density and size of plants in the forest understory. As the demand for energy around the world increased, the privately owned oil and gas reserves below the Allegheny National Forest, left in private ownership when the Forest Service bought land to create the forest, were developed, including the oil and gas reserves beneath the Little Arnot plot. A well was drilled on one end of the plot in 2014. National Forest personnel worked with the owners of the subsurface to minimize the disturbance to the forest, and the Little Arnot plot continues to provide habitat for wildlife and plants. It continues to stabilize the soil and absorb carbon from the atmosphere, but there is also now a large amount of carbon stored in the large trees across the plot.
Here and elsewhere on the Allegheny National Forest and beyond, managers and scientists, industry leaders, colleagues from State agencies, non-governmental organizations, and community leaders are working together to prepare for the new changes facing the Allegheny National Forest as it enters its second century. What will the Little Arnot plot look like when our descendants celebrate the ANF’s bicentennial?
2008
In 2008, the total number of trees was 285 per acre. Black cherry now accounts for 53% of the stocking and 84 trees, while sugar maple was 35% and accounted for 179 trees per acre. There is continued mortality and thinning in number of trees, but the total stocking and volume continued to increase. There are still 8 basswood trees per acre. Diameters of cherry and sugar maple are 14.9 and 10.8 inches, respectively. Cherry increased its average diameter by 1 inch while sugar maple only increased slightly. 10,609 board feet per acre are present in the stand, mostly in black cherry and basswood. The number of species present is 9 in 2008.
2018
The photo from 2018 was taken without an inventory of the stand. Much has happened from 2008 to 2018 making continued comparisons of data challenging. A gas well was installed within the one-acre plot creating an opening in a quarter of the canopy. The photo point is still intact but the overall species composition and stand development data were affected by the oil and gas development that occurred. Data were collected in 2014 just prior to installation of the gas well opening. At this point there were still 9 species present, with 265 trees per acre – 69 black cherry, 172 sugar maple and 8 basswood trees. The merchantable diameter was 14.9 inches, with cherry at 16.1 inches. Total board feet in the stand in 2014 was 12,413 board feet per acre.
This forest has grown for 90 years following a chemical wood clearcut and is now a well-stocked ecologically and commercially valuable forest. It shows the multiple-use nature of the forest by having a gas well present, as well as being a forest with rich soil containing several wildflower species and healthy sugar maple trees. A hiking trail passes nearby and the Little Arnot Run flows just below the stand. This photo series shows the incredible resiliency of our environment, that forests are constantly changing, and that different species grow at different rates.