File:Bulletin (Pennsylvania Department of Forests and Waters), no. 51-55 (1923) (19878576774).jpg

Title: Bulletin (Pennsylvania Department of Forests and Waters), no. 51-55
Identifier: bulletinpennsylv5155penn (find matches)
Year: 1923 (1920s)
Authors: Pennsylvania. Dept. of Forests and Waters
Subjects: Forests and forestry
Publisher: Harrisburg, Pa. : The Department
Contributing Library: Penn State University
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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I I I f I I I (6 \ I I I 5 i ^ k 1 I s I I 4 ^ s <^ *^ «: ^ ^ •• O t/) C/) < O X o w H W < OH 5c/5 ^H OO OS y-A t—c 12; u K H O o » CO I I 10 Two most noticeable exceptions to the average trend are white pine and pitch pine—both intolerant coniferous species. Because of their inability, to thrive under heavy shade of the chestnut, these two trees grew abnormally slowly prior to release from suppression. Even after the chestnut was eliminated it required a considerable period for them to adapt themselves to the changed environment. Hence it is note- worthy that pitch pine had not yet, in 1930, reached its culmination in growth ac- celeration, whereas for white pine to accomplish this required four years longer than other more tolerant hardwood species. It is quite likely that the same tendency would have held true for tulip poplar had there been more individuals representing intermediate and suppressed crown classes. However, it is a rare occurrence to find a tulip which persists after it is truly suppressed, and its dominant trees were more than able to hold their own with chestnut in the struggle for a place in the sun. Because of its intolerance and rapid growth, chestnut was usually dominant in the forest canopy. For that reason and because of its wide distribution it was found to be useful as a site index tree (7). Its dominant position caused many other species to be held back and kept in suppression, which no doubt helps to account for the growth acceleration now shown by individual trees and stands. Rock oak is one of those trees which suffered most from its former association with chestnut. On cer- tain areas the remaining stands of rock oak contain many trees with dead terminal shoots, and great numbers of those in the intermediate and suppressed crown classes are entirely unable to recover. In some instances the weakened condition of the trees has made them increasingly susceptible to disease. Another direct result of the former abundance and dominant position of chestnut is revealed by the fact that height growth of the remaining trees has not kept pace with their increase in basal area. This is to be expected when the forest is opened up considerably, thus reducing the struggle for overhead light and sufficient room for crown development. However, too, some of this decreased height growth is ob- viously associated with an increase in age of the trees. It is significant to contrast the per cent of diameter increase of replacement species for the ten-year period (1920-1930) after death of the chestnut with that of the previous decade (1910-1920). In this connection it should be mentioned that the blight made its appearance on the Mont Alto Forest about 1911, did not become widespread until 1915, and by 1920 all original chestnut was dead. During the recent ten-year period the per cent of diameter increase over that of the previous decade, for different species studied, is as follows: white oak 50 per cent, scarlet oak 55 per cent, rock oak 70 per cent, black oak 90 per cent, red oak 90" per cent, pignut hickory 55 per cent, pitch pine 66 per cent, hemlock 75 per cent, tulip poplar 80 per cent, whereas white pine (based on only 12 trees) outstripped all others when it registered 400 per cent—a rate of growth five times as fast as it was able to accom- plish before death of the chestnut! The average diameter increase for the 608 trees of all species studied was approximately 80 per cent; or, stated in other words, it means that they grew in diameter almost twice as fast as they did before the blight had killed the chestnut. It was found that in most instances the greatest acceleration occurred within five years after the chestnut was dead. When considered from the standpoint of volume production, the growth ac- celeration resulting from loss of the chestnut is even more striking. Explanation lies in the fact that the wider growth rings for the last ten years were added to a larger bole than existed at the beginning of the previous decade. Thus the volume growth of trees closely resembles a problem in compound interest, in which analogy the principal corresponds to the amount of wood capital in the tree, upon which the interest (annual or periodic increment) is regularly superimposed. Since the tree is constantly increasing in size, it becomes evident that diameter growth advances by arithmetical progression, whereas volume growth advances by geometrical pro- 11

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