Indirect effects of N and S deposition on a Norway spruce ecosystem. An update of findings within the Skogaby project

• Published in: Water, air and soil pollution air and soil pollution, 1995-01, Vol.85 (3), p.1613-1622
• Main Authors: Nilsson, L.O, Wiklund, K
• Format: Article
• Language: English
• Subjects: acidification; air pollution; ammonium sulfate; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; biomass; biomass production; conifer needles; deposition; Ecotoxicology, biological effects of pollution; forest soils; Fundamental and applied biological sciences. Psychology; mineral content; nitrogen; nitrogen content; nutrient content; nutrient uptake; nutrients; Picea abies; polluted soils; roots; simulation; soil pH; soil pollution; soil treatment; sulfur; Terrestrial environment, soil, air
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/BF00477211

In this paper we try to interpret results from different investigations where an ecosystem with Norway spruce was manipulated with increased N and S deposition via the soil system. The site, in Skogaby in Southwest Sweden, had 1989-93 an annual deposition of 9 kg NH sub(4)-N; 7 kg NO sub(3)-N and 20 kg SO sub(4)-S ha super(-1). The stand was treated during 6 years with 100 kg N and 114 kg S ha super(-1) y super(-1) in the form of ammonium sulphate (NS treatment). The stand reacted with increased above ground production of 31% after 3 years of treatment. The uptake above ground of N was 155 kg ha super(-1) higher than in the control. Those trends were even stronger after 6 years of treatment. There were no decreases in the uptake of P, K, Ca or Mg (but for B) after 3 or 6 years of NS-treatment. Needle macro nutrient concentrations in relation to N decreased for several nutrients due to dilution effects. As result of the NS treatment pH increased markedly in the litter layer, and less, but significantly, in the humus layer. A decrease in pH value by about 0.3 units was found in the rest of the soil profile down to 50 cm. Dry mass of needle litter fall and litter layer both increased as a result of 6 years of NS-treatment. After three years of treatment 77-80% of all living fine roots in both control and NS treatment were found in the humus layer and the upper 10 cm of the mineral soil. The amount of living fine roots in the humus layer of NS-treated trees decreased to about one third of the control, and the amount of dead fine roots increased by 150% compared with untreated trees after 6 years of treatment. It is argued that the decreased amount of living and increased amount of dead fine roots not necessarily are indications of decreased root vitality. It can also be explained by increased root turnover rate and decreased decomposition rates of N rich new and old fine root litter.