Foliar and soil nutrient relationships in red oak and white pine forests

Red oak (Quercus rubra L.) and white pine (Pinus strobus L.) forests on sandy soils of the northeastern United States may have been depleted of nutrient cations by acid precipitation and intensive land use. Foliar Ca in oak was 5260 mg Ca.kg(-1) dry matter, or more than 3 times the amount in white pine foliage. Red oak also has more Mg, K, and N than white pine. Foliar Al concentration for white pine foliage, 132 mg Al.kg(-1) dry matter, was twice that of red oak foliage. Foliar Ca and N was correlated with basal-area increment. Foliar Ca/Al ratios and Mg levels in pine foliage suggest a risk to tree health. In the organic horizons of both oak and pine forests, bases occupied 80% of the exchange sites. However, in the mineral horizons, Al occupied 96% of the exchange sites. Al may be accumulating in the O horizon. These data indicate that both forest types are susceptible to nutrient imbalances and deficiencies that result from atmospheric deposition and harvesting.