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USDA Forest Service
Northeastern Research Station

Forestry Sciences Laboratory

PO Box 267
Irvine, PA 16329

(814) 563-1040

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Little Arnot Photograph Series

A long wait with a slow modem, but a great 60-year photo record!


In 1927, scientists of the United States Forest Service Allegheny Experiment Station formed a partnership with managers to collect data in stands scheduled to be harvested as part of the first timber sale on the 4-year-old Allegheny National Forest. The data would be used to help managers decide which kinds of silviculture to use. The stands chosen for this timber sale, near the Little Arnot Creek in Warren County, were photographed as well. Scientists continued to collect data and take photographs at about ten year intervals since that timber sale. Inventories consisted of tallies of all trees 1.0 inches in diameter at breast height (dbh) on a 1.0 acre plot within the harvest areas. Some stands were only partially cut, and have since received final harvests. But the stand that grew up after the clearcut in 1928 still stands, and the photographs that follow show the development of this stand, a typical even-age, second-growth stand.

arnot1.jpg This photograph shows the stand prior to harvest in 1927. This stand had a basal area of 128 square feet, with 335 trees per acre. The medial diameter of the merchantable trees was 14.9 inches, and almost 64 square feet, or 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 basal area, respectively.

arnot2.jpg 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.

arnot3.jpg 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, some trees were left, representing 3.1 square feet of basal area, or about 24 trees per acre. The trees that were left had a merchantable medial diameter of 8.4 inches, and were consisted of 8 basswood trees per acre, 12 sugar maples, 3 American beeches, and 1 blue beech.

arnot4.jpg 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). There were 8.1 square feet of basal area per acre, and the new stand was dominated by the shade-intolerant and fast growing black cherry, which represented 2.6 square feet per acre. Residual trees still dominated the merchantable portion of the stand, holding the merchantable medial diameter at 8.8 inches, and basswood and sugar maple, each with several residual trees, joined black cherry as the species with the most basal area 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.

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 are much smaller. The basal area per acre in 1947 was 34.4 square feet, consisting of 497 trees per acre. about one-third of this basal area , or 11.5 square feet, was black cherry, with sugar maple and the short-lived pin cherry representing the second and third most basal area, respectively. The medial merchantable diameter persisted at 8.9 inches, and there were 12 tree species detected in this tally.

By 1958, species became quite distinct. The black cherries in the left foreground had the characteristic flaky bark. The stand was fully stocked, with a relative density of 102%, and a basal area of 107.6 square feet , consisting of 1610 trees per acre! Black cherry continued to dominate, representing 43.6 square feet per acre, followed in order by sugar maple and ostrya. Fourteen tree species were tallied in 1958, including one-time appearances by short-lived species like devil's walking stick and serviceberry.

No tally was made in 1968, but in 1972, the stand had 120.4 square feet of basal area per acre. Self-thinning had reduced the number of trees per acre to 997. Relative density stood at 99%, and the medial diameter of merchantable trees had reached 9.1 inches. Black cherry, sugar maple, and ostrya, in that order, dominated the stand's basal area, with black cherry now representing 56.7 square feet per acre. Twelve tree species were detected during this inventory.

In 1978, basal area per acre had reached 125.8 square feet, in 661 trees per acre. Relative density was 94%, and merchantable medial diameter was 9.7 inches. Black cherry, sugar maple, and basswood, respectively, dominated the stand's basal area, with black cherry representing 65.3 square feet of basal area per acre. 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 medial 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 medial merchantable diameter of 8.7 inches.

arnot9.jpg In 1989, basal area had reached 149.8 square feet per acre, of which 82.4, or 55%, 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 basal area, and basswood, with only 11 trees but 8 % of the basal area, are still the second the third most common species, by basal area. The medial 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 5300 board feet per acre, of which 3400 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.

arnot10.jpg The most recent tally was made in 1998 when total basal area was 158.0 square feet per acre, with total number of trees being 346 per acre. Black cherry accounted for 87.3 square feet of the basal area and 106 of the trees. Sugar maple added 206 trees per acre, and 49.0 square feet of basal area per acre. Eight basswood trees per acre contributing 9.8 square feet of basal area was the third most common species once again, by basal area. Medial diameters for merchantable cherry and sugar maple were 13.2 and 10.2 respectively. The net sawtimeber volume increased in the last ten years to 8032 board feet per acre, of which 5390 board feet were black cherry. The hickory sapling found in the previous tally didn't survive the last ten years, the total number of species found in 1998 was 10.