||Cathryn H. Greenberg
||Southern Research Station
||Forest Ecology and Management. 132: 199-210.
Acorns are an important wildlife food resource and seed source for oak regeneration. Most acorn production studies note wide and consistent differences in acorn productivity among individuals, but none clearly demonstrate determinants of productivity. Acorn production by black, northern red, scarlet, chestnut, and white oak was measured from 1993 to 1997 in the Southern Appalachians was measured and compared among species and individuals. [Acorn production by black, northern red, scarlet, chestnut, and white oak in the Southern Appalachians was measured and compared among species and individuals from 1993 to 1997.] To standardize comparisons among different sized trees and simplify for use by forest managers, the number of acorns per tree were converted to the number/m2 BA (basal area). On average, white oak produced the most acorns and chestnut oak the fewest. Northern red and white oak produced higher green weight and dry biomass than the other three species. There was a significant positive relationship between tree basal area and the number of acorns produced per crown for all species r2 between 0.10 and 0.27). However, this is because larger trees have greater crown areas for producing acorns, and not because they produce more acorns per unit area of crown. Alone, BA was significantly, positively correlated with the number of acorns/m2 BA only in black, northern red (p < 0.06) and white oak (not in scarlet or chestnut oak), but explained little of the variation in acorn production among individuals. Trees [ 25 cm d.b.h. of most species produced significantly fewer acorns/m2 BA than their larger counterparts. However, many small (<23 cm d.b.h.) scarlet oaks originating from a 1967 clear-cut were prolific producers, whereas white oaks (<25 cm d.b.h.) in the same stand were not. Frequency of acorn production ranged from never to yearly among individuals. Good producers (trees producing m 5-year species mean) composed 20 percent (chestnut oak) to 46 percent (northern red oak) of sample populations but contributed disproportionately to the acorn crop in moderate and good crop years. Good producers produced acorns more frequently and had more acorns/m2 BA on fruiting trees than did poor producers. However, in any given year, good and poor producers were similarly represented in the fruiting population. Hence, good producers could not be easily identified by the presence of acorns during poor crop years, nor could poor producers be identified by an absence of acorns in good crop years.
Greenberg, Cathryn H. 2000. Individual variation in acorn production by five species of southern Appalachian oaks. Forest Ecology and Management. 132: 199-210.