Fig. 6. Map of Reservation showing present distribution of black oak (smaller dots) and red oak (larger dots). Neither species is spreading and both are thought to be largely confined to the area that was wooded before 1860.
The large acorns of the red oak are a favorite food of the gray squirrel, which is most numerous on the parts of the Reservation where these trees are present. The red-headed woodpecker on the area tends to concentrate its activities where there are red oaks. The fox squirrel, white-footed mouse, and blue jay are important consumers of the acorns of red oak. A pair of barred owls resided in the deep woods formed by these oaks and the associated trees.
Quercus velutina.—Black oak is one of the dominant species of the original forest climax, and is still one of the more important trees of the woodland. Like chestnut oak it shows little tendency to spread beyond its present limits. Wherever there are small trees there are old mature trees or remains of them nearby. For this reason the present distribution of black oak on the area is thought to fall entirely within the area occupied by the original forest. At present it occurs throughout most of the woodland except in the warmer and drier situations, such as on south slopes. In some hilltop situations it is common, with occasional large mature trees. In some parts of the bottomland and lower slopes it is abundant also, but there are scarcely any on the upper dry rocky slopes that are the preferred habitat of chestnut oak.
Growth in the black oak is somewhat more rapid than in the chestnut oak, as the black oak usually grows on better soil. For 15 the average growth amounted to 3.21 annual rings per inch of trunk diameter.
In 1954 a study of annual rings in a large, long dead, black oak at the bottom of a north slope near the Reservation headquarters showed that the tree was 96 years old, and hence was growing before the area was settled. Within the period of this study black oak underwent reduction in numbers more severe than that noted in any other species of tree on the Reservation. The effect of drought may have been the primary factor, although undoubtedly disease was involved also. In 1953, the second successive drought year, mortality was noticeable. Precipitation continued below normal until August 1954. By then the oaks had been decimated. On a sample strip of hilltop where 29 were recorded, 21 had recently succumbed, and their leaves were dry and withered; two were dying, though still having some green foliage, and only six were surviving, all evidently in critical condition. The mortality included trees of all sizes, even the largest and oldest. No further mortality was noted in 1955 when precipitation was only slightly below normal. On the Reservation there are many old logs, and snags still standing, of mature black oaks long dead. Earlier drought periods such as those of 1936-37 and 1925-26 possibly were also times of unusually heavy mortality. In any case it seems clear that this oak was originally more prominent in the woodlands than it is at present, and has been steadily losing ground. Even where the mature trees remain in greatest numbers the saplings are relatively scarce as compared with those of elm, ash, hackberry, and hickory. The westernmost limits of the range are nearly 100 miles west of the Reservation.
Black oak provides a mast crop which is utilized by various small mammals, notably squirrels and white-footed mice. Gray squirrels have often been noticed in or about these trees. Hairy woodpeckers (Dendrocopos villosus), black and white warblers (Mniotilta varia), and brown creepers (Certhia familiaris) have often been noticed foraging on the trunks. Blue jays, myrtle warblers (Dendroica coronata), tufted titmice, and summer tanagers frequently forage through the crowns. Often black oak trunks are hollow and the cavities are utilized by various birds and mammals including the screech owl (Otus asio), barred owl, raccoon, opossum, fox squirrel, gray squirrel, woodrat, and white-footed mouse.
Quercus marilandica.—Black Jack oak is localized in four small compact groves on the Reservation. These sites, though well separated, are similar. All are on steep lower slopes, where there is dry rocky clay soil and the exposure is mainly south. Probably all four groves date back to the time when the area was still in an undisturbed state. Originally they were perhaps largely separated from the remainder of the woodland. Black Jack oak is more tolerant of heat and drought than most of the other hardwoods are. The species is intolerant of fire, but perhaps was partly protected under original conditions by the sparseness of herbaceous vegetation on the poor soil where the groves were situated.
These oaks are relatively slow-growing. One stump of 9-inch diameter, typical of the larger Black Jack trees, had approximately 60 annual rings. Under present conditions there is little or no reproduction and these trees are dying out as a result of competition by other hardwoods. Under protection from fire and browsing, elms, other oaks, locust and dogwood have closed in about the groves and seem to be shading them out.
There are several mature oaks of anomalous appearance, in different places within a few hundred feet at most of the groves of Black Jack. Most of these appear to be hybrids between the present species and Q. velutina, as they are somewhat intermediate in size, bark texture, and leaves.
This oak produces a mast crop used by various birds and mammals, and groves are frequented by blue jays, fox squirrels, white-footed mice and woodrats. In the mid-forties when the woodrat population was high, there were many of the rats' stick houses in the groves, built either at the bases of the trunks or among the dense branchlets in tops of fallen trees. By 1952 the population of woodrats was much reduced and had disappeared entirely from these groves. The houses were collapsed and decaying.