Raisa Mäkipää. (1994). Effects of nitrogen fertilization on the humus layer and ground vegetation under closed canopy in boreal coniferous stands. Silva Fennica vol. 28 no. 2 article id 5399. https://doi.org/10.14214/sf.a9164

Keywords: ground vegetation; forest soils; dwarf shrubs; nitrogen fertilization; mosses; nitrogen saturation; nitrogen deposition

Abstract | View details | Full text in PDF | Author Info

Forest ecosystems may accumulate large amounts of nitrogen in the biomass and in the soil organic matter. However, there is increasing concern that deposition of inorganic nitrogen compounds from the atmosphere will lead to nitrogen saturation; excess nitrogen input does not increase production. The aim of this study was to determine the long-term changes caused by nitrogen input on accumulation of nitrogen in forest soils and in ground vegetation.

The fertilization experiments used in this study were established during 1958–1962. They were situated on 36- to 63-year-old Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) stands of different levels of fertility. The experiments received nitrogen fertilization 5–7 times over a 30-year period, and the total input of nitrogen was 596–926 kg/ha.

Nitrogen input increased the amount of organic matter in the humus layer and the nitrogen concentration in the organic matter. Furthermore, the total amount of nutrients (N, P, K, Ca and Mg) bound by the humus layer increased due to the increase in the amount of organic matter. However, nitrogen input decreased the biomass of ground vegetation. The nitrogen concentration of the plant material on the nitrogen-fertilized plots was higher than on the control plots, but the amount of nutrients bound by ground vegetation decreased owing to the drastic decrease in the biomass of mosses. Ground vegetation does not have the potential to accumulate nitrogen, because vegetation is dominated by slow-growing mosses and dwarf shrubs which do not benefit from nitrogen input.

Mäkipää, E-mail: rm@mm.unknown

Category : Research article

article id 207, category Research article

Mats T. Olsson, Maria Erlandsson, Lars Lundin, Torbjörn Nilsson, Åke Nilsson, Johan Stendahl. (2009). Organic carbon stocks in Swedish Podzol soils in relation to soil hydrology and other site characteristics. Silva Fennica vol. 43 no. 2 article id 207. https://doi.org/10.14214/sf.207

Keywords: temperature sum; soil organic carbon; forest land; soil hydrological class; N deposition; latitude; site capacity; mean annual precipitation; altitude

Abstract | View details | Full text in PDF | Author Info

Site characteristics influence soil organic carbon (SOC) stocks. In Podzols under Swedish forest land, SOC stocks were related to latitude, altitude, soil hydrological class categorized by mean groundwater level, mean annual precipitation, temperature sum during the growing season, total annual nitrogen (N) deposition and site capacity. SOC stocks were determined for the O-horizon and for total soil (O-horizon + mineral soil to a depth of 50 cm). Data from the Swedish National Forest Soil Inventory 1993–2001 were used (1477 field plots). The O-horizon was sampled with a core sampler and carbon (C) stocks were determined. For the mineral soil layers the SOC stock was calculated based on the SOC concentrations, bulk density and content of rock fragments. The results showed that the overall mean SOC stock was 2.8 and 8.2 kg C m^–2 for O-horizon and total soil, respectively. Soil hydrological class strongly affected SOC stocks, which increased from on average 6.7 kg C m^–2 at dry sites to 9.7 kg C m^–2 at slightly moist sites. Corresponding values for the O-horizon were 2.0 to 4.4 kg C m^–2. The correlation coefficients for the linear relationship between SOC stock and site characteristics were highest for N deposition, which explained up to 25% of variation, and latitude, which explained up to 20% of variation. Altitude had the lowest degree of explanation.

Olsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden E-mail: mto@nn.se
Erlandsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden E-mail: me@nn.se
Lundin, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden E-mail: ll@nn.se
Nilsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden E-mail: torbjorn.nilsson@mark.slu.se
Nilsson, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden E-mail: an@nn.se
Stendahl, Swedish University of Agricultural Sciences, Dept of Soil and Environment, Uppsala, Sweden E-mail: js@nn.se

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