Effects of added nitrogen on growth of hardwood trees in southern New York

Abstract

Nitrogen fertilization rate trials (0–672 kg/ha) were established in seven second-growth mixed deciduous forest stands in southern New York, on well to somewhat poorly drained soils typical of better hardwood sites, with no history of fire or cultivation. Basal-area growth over 20 years was determined from increment cores of dominant and codominant trees. Significant growth response occurred only for black cherry (Prunusserotina Ehrh.). Nitrogen additions of 168–336 kg/ha increased growth 21% over 5–10 years. Ten-year basal-area growth response of sugar maple (Acersaccharum Marsh.) and white ash (Fraxinusamericana L.) was less than in other fertilization studies. The lack of response is attributed to favorable nitrogen status of the soils, resulting from lack of disturbance over at least the last four decades and, possibly, atmospheric input of nitrogen.