Critical loads for soil in Norway, Nordmoen

We evaluate the critical load for soil and water at Nordmoen using the dynamic model Magic, the static PROFILE model, and the empirical method as suggested by the mapping handbook. Nordmoen is located about 60 km N of Oslo on thick deposits of glaciofluvial sands, and receives moderate (for Norway) levels of acid deposition (53 meqSO4/m²/yr). At Nordmoen both acid deposition and forestry practices have caused soil acidification. MOGIC indicates that the "tolerable" load is 0 meq SO4/m²/yr under the conditions that the CA/AL molar ratio in soil solution be above 1 or 0.5. The estimate assumes that forestry practices will continue for the next 50 years. The empirical method for waters gives a critical load estimate of 126 meq SO4/m²/yr. Nordmoen is thus a site in Norway at which the soil and forest are more sensitive than surface waters. These results can be used to determinate under which circumstances forest will be more sensitive than fish, and thus provide a basis for mapping critical load

Critical loads for soils in Norway. Preliminary assessment based on data from 9 calibrated catchments

Critical load for acid deposition with respect to soils are calculated for 9 calibrated catchments in southern Norway. Two methods recommended by the UN-ECE Handbook on Mapping Critical Loads were used: The stratic empirical model, and the dynamic MAGIC model. The critical load for soils follow two criteria: runoff water must have alkalinity > 0 (fish criterion), and the Al/Ca equivalent ratio in soil solution < 1.5 (forest criterion). The results show that for these Norwegian sites with thin and patchy soils, the fish criterion is always the more strigent. Further work should evaluate regional soils data and assess the future role of nitrogen.Norwegian Directorate for Nature Management (DN

Soil Solution Response to Experimental Addition of Nitrogen to a Forested Watershed at Gårdsjön, Sweden

Nitrogen has been added to a forested 0.52 ha headwater catchment at Gårdsjön on the southwest coast of Sweden to study the ecosystem response to elevated nitrogen deposition. The catchment is dominated by naturally generated, mixed-age conifers, mainly Norway spruce, with Scots pine in dry areas. After a pre-treatment period of about 1 year, nitrogen was added to the whole catchment as ammonium nitrate by means of sprinklers at an intensity of 3 mm h−1 (average concentration 230 mmol N1−1). Total nitrogen input as throughfall to the catchment increased from the ambient 12.5 kg N ha−1 year−1 in the pre-treatment year to a total of 47.3 kg N ha−1 year−1 in the treatment years. Soil solutions were collected using tension lysimeters at four locations covering a moisture gradient from the dry upper to the wet lower parts of the watershed. Results from these locations were compared with soil solution composition at two locations in a nearby control catchment. After 2 years of nitrogen addition, the volume-weighted average nitrate concentrations in the treated catchment were higher than the pretreatment values, especially in the upper soil. Concentrations showed a progressive increase over time. The lack of the same increasing trend in the control catchment precludes natural variations in climatic conditions as the main cause for this increase. Relative to inputs, nitrate concentrations in soil solution were low and showed large variations between the drier and wetter locations. Differences in nitrate concentrations between pre-treatment and treatment periods declined with soil depth, indicating that most of the added nitrogen was consumed in the upper soil. The results from soil solution do not indicate increased nitrogen leaching below the rooting zone in the treated catchment and thus based on these results alone there is as yet no indication of nitrogen saturation

Recovery from Acidification

Over the past decade there has been considerable interest in the effects of atmospheric deposition on forest ecosystems. This volume summarizes the results of the Integrated Forest Study (IFS), one of the most comprehensive research programs conducted. It involved intensive measurements of deposition and nutrient cycling at seventeen diverse forested sites in the United States, Canada, and Norway. The IFS is unique as an applied research project in its complete, ecosystem-level evaluation of nutrient budgets, including significant inputs, outputs, and internal fluxes. It is also noteworthy as a more basic investigation of ecosystem nutrient cycling because of its incorporation of state-of-the-art methods, such as quantifying dry and cloud water deposition. Most significantly, the IFS data was used to test several general hypotheses regarding atmospheric deposition and its effects. The data sets also allow for far-reaching conclusions because all sites were monitored over the same period using comparable instruments and standardized protocols

Akkumulering av nitrogen- variasjoner avhengig av bestandsutvikling, nitrogentilførsel og simulert snødekke

Fra Institutt for jord- og vannfag. Rapport nr. 10/97 (60). Prosjektnummer NATI 17/96. Miljøverndepartementet fagrapport nr. 90. Oppdragsgiver: Direktoratet for Naturforvaltning.Kunnskap om hvor mye N som kan akkumuleres i jordsmonnet er av stor betydning for beregning av tålegrenser for N i skogøkosystemet. Formålet med denne undersøkelsen var å fremskaffe bedre estimater for netto N-immobiliseringshastighet i skogsjord og spesielt hvordan den påvirkes av bestandsalder, N-tilførsel og isolerende snødekke

Nitrogen fra fjell til fjord. Årsrapport 1995. (Nitrogen from mountains to fjords - yearly report 1995)

Programmet "Nitrogen fra fjell til fjord" har som hovedmål å øke kunnskapen om opptak, omsetning, retesjon og avrenning av nitrogen, og å gi bedre prognoser for framtidige effekter av endringer i nitrogenkretsløpet på jord, skog, ferskvann og fjorder. Aktivitetene er konsentrert om Bjerkreimsvassdraget i Rogaland (685 km² med 5% dyrket mark) og Aulivassdraget i Vestfold (366 km² med 32% dyrket mark). I Bjerkreimsvassdraget er atmosfærisk tilført nitrogen av størst betydning, mens i Aulivassdraget er landbruket dominerende nitrogenkilde. Feltprogram med tilhørende spesialstudier ble startet i 1992 og avsluttet i 1995

Nitrogen fra fjell til fjord. Årsrapport 1995. (Nitrogen from mountains to fjords - yearly report 1995)

Programmet "Nitrogen fra fjell til fjord" har som hovedmål å øke kunnskapen om opptak, omsetning, retesjon og avrenning av nitrogen, og å gi bedre prognoser for framtidige effekter av endringer i nitrogenkretsløpet på jord, skog, ferskvann og fjorder. Aktivitetene er konsentrert om Bjerkreimsvassdraget i Rogaland (685 km² med 5% dyrket mark) og Aulivassdraget i Vestfold (366 km² med 32% dyrket mark). I Bjerkreimsvassdraget er atmosfærisk tilført nitrogen av størst betydning, mens i Aulivassdraget er landbruket dominerende nitrogenkilde. Feltprogram med tilhørende spesialstudier ble startet i 1992 og avsluttet i 1995