PARENT SESSION
Oral Session # 38: Forest Ecology II: Soils, Carbon, and Nutrient Cycling.
Presiding: B Clinton
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 100.
Base cation nutrition, stress and sugar maple health in the northeastern United States.
Horsley, Stephen*,1, Long, Robert2, Hallett, Richard3, Bailey, Scott4, 1 USDA Forest Service, NERS, Irvine, PA, USA2 USDA Forest Service, NERS, Delaware, OH, USA3 USDA Forest Service, NERS, Durham, NH, USA4 USDA Forest Service, NERS, Campton, NH, USA
ABSTRACT- Sugar maple (Acer saccharum Marsh.) decline disease has occurred sporadically in the northeastern United States and eastern Canada during the past 50 years. Typically, crown vigor deteriorates, progressing through fine twig and branch dieback, frequently ending in tree mortality. Sugar maple decline usually has been associated with excessive stress, particularly from insect defoliation. The most recent sugar maple decline episode occurred on the Allegheny Plateau in northern Pennsylvania. We evaluated crown health, foliar nutrition and stress histories in a total of 84 stands in Pennsylvania, New York, Vermont and New Hampshire that included the range of soil and geologic sites where sugar maple is found in the northeastern United States. Crown health was evaluated on three 400 m2 plots per stand using North American Maple Project protocols. Foliar chemistry was analyzed on 5 asymptomatic trees per stand and stand stress history was evaluated using a digitized defoliation database and through interviews with landowners. Foliar chemistry was a good index of site quality. Examination of 43 stands in western Pennsylvania and New York showed that trees on sites with low foliar Mg and Ca, high foliar Mn and excessive defoliation stress had poorer crown vigor and higher mortality than those with better nutrition or those with poor nutrition that lacked excessive defoliation stress. Examination of trees in 41 additional stands with similar ranges of foliar Mg, Ca and Mn, but lacking defoliation stress, in central and eastern New York, Vermont and New Hampshire showed that crown vigor was poorer for sites with low foliar Mg and Ca and high foliar Mn, but little or no mortality occurred. Overall, our study suggests that sugar maple is predisposed to poorer crown vigor by imbalanced Mg, Ca and Mn nutrition and incited to mortality by excessive stress, particularly from defoliation.
Key words: decline disease, sugar maple, base cation nutrition, defoliation stress