Soil-Mediated Effects of Atmospheric Deposition on Eastern U.S. Spruce-Fir Forests

Abstract

The coincident observations of Waldsterben in Germany and red spruce decline in the northeastern U.S. has naturally led to some speculation that similar mechanisms may be involved. In the German situation, soil-mediated hypotheses played (and still play) a major role; namely, soil acidification and aluminum toxicity (Ulrich et al. 1980) and base cation deficiencies (especially Mg; Rehfuess et al. 1987, Hüttl and Wisniewski 1987). In the red spruce case, there has been much concern that cation deficiencies and/or Al toxicity may also play a major role (Tomlinson 1983). Other soil-related hypotheses invoke nitrogen, either as deficient (Pastor et al. 1987) or in excess (“nitrogen saturation”; Friedland et al. 1984, Evans 1986). As a result of these concerns, a considerable amount of research was initiated in the mid 1980s on soils and nutrient cycling in spruce-fir ecosystems in both the northeastern and southeastern U.S. This research has allowed evaluations of some of the hypotheses for red spruce declining and substantially contributed to our knowledge of the soils, nutrient status, and nutrient cycling of these ecosystems.