Damage to Seedlings by Animals

Deer populations in certain areas of the central Appalachians are so high, that understory browse lines are quite visible. As the deer population increases, there will be public, and thus political, resistance to increasing deer control measures for the sake of forestry purposes. In the future, much of the Appalachian forests could have a browse line similar to parts of the northeastern forests. When this occurs, it is too late for quick remedial actions. (C. Smith, 1993)

The potential for deer browsing to block the development of competitive oak advance regeneration is better documented than insect damage. The deer population on the Allegheny Plateau in Pennsylvania (often more than 30 per square mile) is sufficient to create open, park-like stands with little undergrowth. Where deer populations are high, browsing can occur on oak seedlings that are as short as 15 in. high (Galford and others 1991). Sometimes there is so little advance regeneration of hardwoods that clearcuts revert to grass and scattered shrubs (Marquis 1974). (Lorimer, 1993)

Published evidence on the effects of deer browsing on oak is very limited outside of Pennsylvania. Similarly severe effects have been documented elsewhere, but the problem is often quite localized. High deer populations (34-59 per square mile) in a game preserve in Massachusetts have created savanna-like conditions, but in the surrounding region the deer average only 3-8 per square mile and browsing is limited (Healy and Lyons 1987). The intensity of deer browsing appears to vary greatly from place to place. Four underplanting trials of northern red oak in southern Wisconsin have shown little browsing in two counties with average deer populations of 18 per square mile (Pubanz and Lorimer 1992), but destructive levels of browsing in counties with average deer densities of 25-35 per square mile (Pubanz and Lorimer, personal observations). In the mountains of West Virginia, moderate-sized clearcuts (e.g., 20 acres) develop so much vegetation that the ability of deer to modify the outcome is limited (H. C. Smith, personal communication). While deer browsing was observed on oak seedlings in a southern Appalachian cove stand, and may have contributed to the slow growth rate (Beck 1970), the problem of slow growth persisted long after the deer density had greatly diminished (D. E. Beck, personal communication). (Lorimer, 1993)

Deer browsing is clearly a limiting factor for oak regeneration in some places, and the substantial growth of deer populations that occurred in many areas around the 1930s does coincide with the beginning of widespread oak problems. However, the occurrence of oak regeneration failures in places where deer are not especially numerous makes a number of researchers feel that deer are generally more of an aggravating factor than a primary limiting factor. We need more evidence, however, on the effects of moderate deer browsing on growth rates, especially where deer may be browsing oak in preference to other species (George and others 1991). Furthermore, the deer problem seems to be getting progressively worse. Deer populations in the lower Midwest were historically low (USDA Forest Service 1970) but appear to have increased substantially in recent years (e.g., Ishmael 1990). As one forester in Indiana remarked, complaints about deer damage are becoming more numerous, and establishing a hardwood plantation is often like "setting the table for deer." (Lorimer, 1993)