The effects of acid deposition on the biogeochemical cycles of major nutrients in miniature red spruce ecosystems

• Published in: Biogeochemistry 1994-01, Vol.24 (2), p.85-114
• Main Authors: Sherman, R.E. (Cornell Univ., Ithaca, NY (USA). Dept. of Natural Resources), Fahey, T.J
• Format: Article
• Language: English
• Subjects: ACID RAIN; Acid soils; Agronomy. Soil science and plant productions; AIR POLLUTION; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; CATION; CATIONES; CATIONS; CICLO BIOGEOQUIMICO; CRECIMIENTO; CROISSANCE; CYCLE BIOGEOCHIMIQUE; CYCLING; ECOSISTEMA; ECOSYSTEME; ECOSYSTEMS; Ecotoxicology, biological effects of pollution; Forest ecosystems; Forest soils; Fundamental and applied biological sciences. Psychology; GROWTH; LEACHING; LESSIVAGE DU SOL; LIXIVIACION; LLUVIA ACIDA; Mineral soils; NUTRIENTES; NUTRIENTS; Organic soils; PICEA RUBENS; Plant roots; PLUIE ACIDE; POLLUTION ATMOSPHERIQUE; POLUCION DEL AIRE; Soil and water pollution; Soil ecology; Soil horizons; Soil science; SUBSTANCE NUTRITIVE; Terrestrial environment, soil, air
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/bf02390181

As part of an experimental study of air pollution effects on tree growth and health, we combined process studies with an ecosystem approach to evaluate the effects of acidic deposition on soil acidification, nutrient cycling and proton fluxes in miniature red spruce ecosystems. Ninety red spruce saplings were transplanted into 1-m diameter pots containing reconstructed soil profiles and exposed to simulated acid rain treatments of pH 3.1, 4.1 and 5.1 for four consecutive growing seasons. All the principal fluxes of the major elements were measured. During the first year of treatments, the disturbance associated with the transplanting of the experimental trees masked any treatment effects by stimulating N mineralization rates and consequent high NO3-, cation, and H+ flux through the soil profile. In subsequent years, leaching of base cations and labile Al was accelerated in the most intensive acid treatment and corresponding declines in soil pH and exchangeable pools of Ca and Mg and increases in exchangeable Al concentrations were observed in the organic horizon. Leaching of Ca2+ and Mg2+ also was significantly higher in the pH 4.1 than in the pH 5.1 treatment. Flux of Ca from foliage and soil was increased in response to strong acid loading and root uptake increased to compensate for foliar Ca losses. In contrast, K cycling was dominated by root uptake and internal cycling and was relatively insensitive to strong acid inputs. Cation leaching induced by acidic deposition was responsible for the majority of H+ flux in the pH 3.1 treatment in the organic soil horizon whereas root uptake accounted for most of the H+ flux in the pH 4.1 and 5.1 treatments. Although no measurable effects on tree nutrition or health were observed, base cation leaching was significantly accelerated by acidic deposition, even at levels below that observed in the eastern U.S., warranting continued concern about acid deposition effects on the soil base status of forested ecosystems.