Table 2.—Percentages of Different Kinds of Small Trees (Six Inches to a Foot in Trunk Diameter) on Different Slope Exposures.
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| North slopes | Hilltops | West slopes | South slopes | |
| | | | |
| Elm | 29.6 | 29.9 | 34.6 | 57.9 |
| Chestnut oak | 29.6 | 17.5 | 15.5 | .4 |
| Hickory | 11.1 | 25.4 | 28.4 | .8 |
| Walnut | 5.6 | .7 | 7.4 | 5.3 |
| Hackberry | 13.0 | 1.0 | 3.7 | 26.4 |
| Black oak | 1.9 | 16.3 | ||
| Red oak | 1.9 | 6.8 | ||
| Locust | 3.3 | 3.0 | ||
| Osage orange | 2.0 | 1.5 | ||
| Coffee-tree | 1.9 | .7 | 1.1 | |
| Cherry | .4 | |||
| Red haw | 2.4 | |||
| Mulberry | .7 | |||
| Redbud | 9.3 | 3.7 | .8 | |
| Boxelder | 2.6 | |||
| | | | |
| Total trees in sample | 54 | 295 | 162 | 266 |
In 1949 soon after the discontinuance of grazing and cultivation, a large crop of tree seedlings became established. Each year thereafter the numbers were augmented by new crops of seedlings, but conditions rapidly became less favorable for their establishment, as the ground cover of herbaceous vegetation became thicker. The numbers and kinds of young trees that became established differed markedly in different situations. The seedlings present in large numbers were those of elm, honey locust, boxelder, dogwood, walnut, osage orange and crab-apple. There was none of the climax species—oaks or hickories—in the sample.
Table 3.—Numbers of Young Trees Per Acre in Fields of the Reservation, June, 1952.
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| Bottomland pasture | Hilltop pasture | Bottomland fallow field | Hilltop fallow field | Prairie | |
| | | | | |
| No. of 1⁄100 acre plots sampled | 250 | 80 | 70 | 80 | 50 |
| | | | | |
| Honey locust | 83.0 | 58.8 | 5.6 | ||
| Elm | 80.0 | 72.5 | 138.8 | 230.0 | 150.0 |
| Boxelder | 1.6 | 1.2 | 22.9 | 200.0 | |
| Dogwood | 18.8 | 18.8 | 11.4 | 51.2 | 44.0 |
| Walnut | 2.0 | 50.0 | 7.15 | ||
| Osage orange | 16.0 | 48.7 | |||
| Crab-apple | 7.2 | 93.8 | 1.2 | ||
| Red haw | 5.2 | 17.5 | 2.8 | 2.5 | 4.0 |
| Coffee-tree | 4.8 | 1.2 | |||
| Hackberry | 2.8 | 2.0 | |||
| Cottonwood | .2 | ||||
| Ash | 8.8 | 3.7 | |||
| Plum | .8 | ||||
| Peach | .2 | ||||
| Cockspur thorn | .8 | 21.3 | |||
| Sycamore | .4 | 1.2 | |||
| Cherry | 1.2 | 2.0 | |||
| | | | | |
| Total number counted | 236 | 393 | 279 | 296 | 402 |
| | | | | |
[Table 3] shows the numbers of young trees counted in a total of 530 plots of 1⁄100 acre each, in June, 1952. The trees counted included all those approximately one foot high or larger. A few were up to 12 feet tall, but most were between one foot and five feet in height. Not included were the many smaller seedlings, which were mostly concealed beneath the dense layer of low herbaceous vegetation.
Of young trees there were most on the bluestem prairie area, less on the former pastures and least on the fallow fields. In both the pasture areas and the fallow fields, the bottomlands had fewer trees than the hilltops—60 per cent and 94.3 per cent, respectively. In every instance the abundance of young trees seemed to be inversely proportional to the amount of competing herbaceous vegetation. The bottomland fallow fields, which had the fewest tree seedlings, were dominated by a rank growth of giant ragweed and sunflower, often as much as ten feet tall, effectively shutting most of the light from the tree seedlings. By 1954, however, the sunflower was nearly eliminated, and the giant ragweed, though still abundant, was much stunted.
The bluestem prairie on an area of hilltop and upper slope had not been burned over or otherwise disturbed for some years prior to 1948, and probably trees began to invade this area years before they invaded the fallow fields and pastures accounting, in part, for their greater abundance in 1952. Approximately half of the young trees on this prairie area were boxelders, which were relatively scarce on the other four areas. Elm was either first or second in abundance on each area. On both types of pasture areas honey locusts were appearing in abundance and osage orange seedlings were present in somewhat smaller numbers. However, these two kinds of trees were almost entirely absent from the other areas sampled, except that a few locusts were recorded on a hilltop fallow field. In 1948 honey locust seeds were noticed in great abundance in the droppings of cattle; their dispersal in this manner probably is in large part responsible for the abundance of young honey locusts throughout the former pastures. Osage orange may have been distributed in the same manner. Seedlings of dogwood were moderately numerous on each one of the areas sampled, and those of red haw were somewhat less abundant on each area. Crab-apple was the most abundant species invading the hilltop pastures but was scarce or absent in the other situations. The remaining species of trees, including coffee-tree, hackberry, cottonwood, ash, plum, peach, cherry, cockspur thorn, sycamore, and redbud, each made up only a small percentage of the tree crop in the situations where they occurred.
In late July and early August, 1954, counts of young trees were made again on the upland pasture area, with a total of 200 1⁄100-acre plot samples. This sample was taken at the end of one of the longest and most severe droughts in the history of the area. Both 1952 and 1953 had drought summers, and up to the end of July the summer of 1954 was exceptionally dry also. The conditions of the young trees at this time, in the relatively dry and shallow hilltop soil, was especially significant. As might have been anticipated, in this 1954 count, young trees were more numerous than they had been on any of the areas sampled in 1952. However, the data for 1952 and 1954 are not entirely comparable, because in 1952 none of the plots sampled was nearer than 50 feet to the edge of the woods, whereas in 1954, the sample was arranged to be representative of the entire field, including the parts adjacent to the woods. The numbers per acre of each kind of tree, and the percentages that were dead or dying, were as follows: crab-apple 167 (33.5 per cent dead); locust 98 (3 per cent dead); elm 69.5 (2.9 per cent dead); osage orange 63.5 (none dead); walnut 36.5 (4.1 per cent dead); red haw 25.5 (none dead); ash 19.5 (none dead); cockspur thorn 17 (17.6 per cent dead); wild plum 14 (3.6 per cent dead); dogwood 9.5 (none dead); prickly ash 2 (25 per cent dead); black oak 1.5 (none dead); boxelder .5 (none dead). Thus, of the species that were prominent invaders of the field, only crab-apple showed heavy mortality. In many instances the mortality in crab-apple was due wholly or in part to attack by cottontails (Sylvilagus floridanus), which had completely girdled many of the stems. In general, mortality in the young trees was light in this grassland area compared with the mortality in any part of the woodland.