Fate of the 2001 acorn crop at Clear Creek State Forest, Pennsylvania
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In: Fei, Songlin; Lhotka, John M.; Stringer, Jeffrey W.; Gottschalk, Kurt W.; Miller, Gary W., eds. Proceedings, 17th central hardwood forest conference; 2010 April 5-7; Lexington, KY; Gen. Tech. Rep. NRS-P-78. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 253-261.
One of the key steps in the oak regeneration process is the successful germination of acorns into new seedlings. Several factors can greatly reduce or entirely destroy a red oak acorn crop between seed fall in the autumn and germination the following spring. In 2001, a bumper acorn crop occurred on Clear Creek State Forest in Jefferson County, PA. This event coincided with the installation of a root development study and the establishment of an oak silviculture short course for SILVAH. This fortuitous coincidence allowed for a series of three simple experiments to evaluate factors affecting acorn overwintering success and subsequent seedling survival. The crop was estimated at approximately 210,000 acorns per acre for all oak species. Insect infestation of the acorns varied among stands, with infestation rates ranging from 5 to 20 percent. Overwintering success of unburied sound acorns was 20 percent, but burial increased survival to more than 80 percent. Unburied acorns succumbed to desiccation (48 percent), insect infestation (15 percent), disease (15 percent), and consumption by wildlife (2 percent). Seedlings that germinated from acorns outside of deer fences and in dense understory shade had the lowest survival rate (2 percent) during the next 8 years. Excluding the deer or reducing the dense understory shade increased survival rates to approximately 26 percent during the same period. Seedlings in fenced, partial-shade stands had an 8-year survival rate of 56 percent. These data indicate that: 1) oak management activities need to be flexible and opportunistic to take advantage of mast years; 2) there is a several-year window for management following such an event; and 3) dense understory shade and excessive deer browsing are two major obstacles to establishing new oak seedlings, an essential step in the oak regeneration process, at Clear Creek State Forest.
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Brose, Patrick. 2011. Fate of the 2001 acorn crop at Clear Creek State Forest, Pennsylvania. In: Fei, Songlin; Lhotka, John M.; Stringer, Jeffrey W.; Gottschalk, Kurt W.; Miller, Gary W., eds. Proceedings, 17th central hardwood forest conference; 2010 April 5-7; Lexington, KY; Gen. Tech. Rep. NRS-P-78. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 253-261.