Publikasjoner
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2010
Forfattere
Heleen de Wit Toril Eldhuset Jan MulderSammendrag
Dissolved aluminium (Al) in soils, mobilized by acid deposition, is considered a threat to forest health through hampering root growth and nutrient uptake. Since the end of the 1980s dissolved Al in forest soil water plays a key role in the assessment of critical loads of acid deposition. So far, most evidence for toxicity of dissolved Al in forest soil water is based on nutrient solution studies and pot experiments. Here, we present results from one of the few in situ ecosystem-scale forest manipulation experiments to study the effect of Al on mature forest trees. A plotwise addition of dilute AlCl3 was conducted during seven years in an even-aged spruce forest (Picea abies) in an area in Norway with low acid deposition. Soil solution concentrations of Al were increased to potentially toxic levels (up to 500 mu mol L-1) and base cation (Ca + Mg + K) to inorganic Al ratios in the soil solution in the root zone were mostly below 1 in the Al-addition treatments. In the control treatment (only water addition) Al concentrations did not exceed 15 mu mol L-1 and base cation to inorganic Al ratios were above 1. The toxic effects of Al on fine root growth and plant growth found in hydroponic studies and pot trials are not confirmed by this field manipulation. However, magnesium (Mg) contents in needles decreased significantly and persistently in plots with elevated Al concentrations, whereas the needle Ca content did not respond. The depletion of the Mg content in needles is suggested to be due to antagonistic effects of high Al concentrations at the root surface, consistent with observed reductions in Mg to Al ratio of inner bark. This study clearly supports a role for Al in critical load functions for forests as dissolved Al causes a decrease in uptake of Mg. However, other signs of reduced forest vitality were not observed. Soil base cation status may need to be included in risk evaluations of forest health under acid deposition. (C) 2010 Elsevier B.V. All rights reserved.
Sammendrag
We investigated concentrations of dissolved organic carbon (DOC) in throughfall and soil solutions at 5, 15 and 40-cm depth in 16 Norway spruce and two Scots pine plots throughout Norway between 1996 and 2006. Average DOC concentrations ranged from 2.3 to 23.1 mg/l and from 1.1 to 53.5 mg/l in throughfall water and soil solutions, respectively. Concentrations of DOC in throughfall and soil waters varied seasonally at most plots with peaks in the growing season. By contrast to recently reported positive long-term trends in DOC concentrations in surface waters between 1986 and 2003, soil water data from 1996 to 2006 showed largely negative trends in DOC concentrations and no significant trends in throughfall. However, regression analysis for individual sites, particularly at 5- and 15-cm soil depths, showed that DOC concentrations in soil water were significantly and negatively related to non-marine sulphate (SO4) and chloride (Cl-). The lack of a long-term increase in DOC in soil water in the period May 1996-December 2006 may be due to the relatively small changes in the deposition of SO4 and Cl- in this period.
Sammendrag
Transport and turnover of dissolved organic carbon (DOC) is important in the C cycle of organic soils. The concentration of DOC in soil water is buffered by adsorption to the soil matrix, and has been hypothesized to depend on the pool size of adsorbed DOC. We have studied the effect of frequent artificial excessive leaching events on concentration and flux of DOC in shallow, organic rich mountain soils. Assuming a constant Kd value for DOC adsorption to the soil matrix, we used these data to assess the change in the pool of adsorbed (or potential) DOC in the soil. The study involved manipulation of precipitation amount and frequency in summer and autumn in small, heathland catchments at Storgama, southern Norway. The shallow soils (16-34 cm deep on average) limit the possibility for changes in water flow paths during events. The mini-catchments range in size from 75 to 98 m(2). Our data show that after leaching of about 1.2 g DOC m(-2) the DOC concentration in runoff declines by approximately 50%. From this we conclude that the pool size of adsorbed potential DOC in the shallow soils at any time is of the order 2-3 g m(-2). Frequent episodes suggest that the replenishment rate, which depends on the decomposition rate of soil organic matter, is fast and the potential DOC pool could be fully restored probably within days during summer, but with some more time required in autumn, due to lower temperatures. Both pool size of potential DOC and replenishment rate are seasonally dependent. The pool of potential DOC, and thus the DOC concentration in discharge, is at their maximum in the growing season. However, under non-leaching conditions, the concentration of DOC in soil water and thus the pool size of potential DOC seems to level off, possibly due to conversion of DOC to less reversibly bound forms, or to further decomposition to CO2.
Sammendrag
We investigated concentrations of dissolved organic carbon (DOC) in throughfall and soil solutions at 5, 15 and 40 cm depth in 16 Norway spruce and 2 Scots pine plots throughout Norway between 1996 and 2006. Average DOC concentrations ranged from 2.3 mg/l to 23.1 mg/l and from 1.1 mg/l to 53.5 mg/l in throughfall water and soil solutions, respectively. Concentrations of DOC in throughfall and soil waters varied seasonally at most plots with peaks in the growing season. By contrast to recently reported positive long-term trends in DOC concentrations in surface waters between 1986 and 2003, soil water data from 1996 to 2006 showed largely negative trends in DOC concentrations and no significant trends in throughfall. However, regression analysis for individual sites, particularly at 5 and 15 cm soil depths, showed that DOC concentrations in soil water were significantly and negatively related to non-marine sulphate (SO4) and chloride (Cl-). The lack of a long-term increase in DOC in soil water in the period May 1996 – December, 2006 may be due to the relatively small changes in the deposition of SO4 and Cl- in this period.
Sammendrag
Dissolved organic nitrogen (DON) plays an important ecological role in forest ecosystems, and its concentration is related to that of dissolved organic carbon (DOC). We investigated DON concentrations and ratios of DOC to DON in throughfall and soil waters in 16 Norway spruce and two Scots pine forest stands sampled at weekly intervals between 1996 and 2006. The stands are all included in the ICP Forests Level II monitoring program and are located throughout Norway. DON concentrations were significantly and positively related to DOC concentrations in throughfall (r (2) = 0.72, p < 0.0001) and soil water at 5, 15, and 40 cm (r (2) = 0.86, 0.32, and 0.84 and p < 0.0001, 0.04, and < 0.0001, respectively). At most sites, the annual median DOC/DON ratio in throughfall ranged from 20.3 to 55.5, which is lower than values in soil water, which ranged from 24.5 to 81.3, gradually decreasing with soil depth. DON concentrations varied seasonally in throughfall at many plots and in soil water at 5-cm depth at one plot only, with higher values in the growing season, but there was no noticeable seasonality at greater depth. The ratios of DOC/DON in soil water were significantly positively related to the C/N ratio in soil at the same depth. Above-ground litter input was the main factor having a significant, negative relationship to DOC/DON in soil water at all depths studied. This might reflect the effect of site conditions on both DOC/DON ratios and litter quantity.
Forfattere
Andreas C. Drichoutis Rudolfo M. Jr. Nayga Panagiotis LazaridisSammendrag
Det er ikke registrert sammendrag
Sammendrag
Bioforsk -Jord og Miljø og UMB (IPM ) har samarbeide med Warsaw University of LIfe Sciences, Deparment of Water engineering gjennom prosjektet :" Prediction and the reduction of diffuse pollution , solid emission and extreme flows from rural areas". Financed with grants from the EEA Financial Mechanism and the Norwegian Financial Mechanism and Resource for Science. This monograpy is a Polish version of results and recommendations from the project. The Norwegian contribution in this chapter summaraize Norwegian experiences with measures to reduce diffuse pollution from agrocultural areas. English title: Best management practice to keep good water quality of surface waters in rural areas in Norway.
Sammendrag
During the first few weeks of life, chicks of the capercaillie (Tetra urogallus) and black grouse (T. tetrix) subsist mainly on insects, of which lepidopteran and hymenopteran larvae are the main components. We studied the breeding phenology of these two species and examined how the timing of breeding was related to the temporal distribution of their larval food source. During a five-year survey, capercaillie mated and hatched consistently four to six days before black grouse. Depending on the vegetation type, the number of larvae (>= 2 mm in length) increased between five and ten times within 10 days, and hatching coincided roughly with the peaks in larval numbers. Due to body growth, however, larval abundance in terms of volume was reached later and occurred 8-9 and 13-14 days after the mean hatching dates in the two species, respectively. Slightly later development of Hymenoptera as compared with that of Lepidoptera contributed in extending the period of high larval abundances for more than one week. The timing of breeding of the two species appears, therefore, to match the temporal distribution of insect food for the fast-growing chicks as they hatch several days before the peak in larval volumes. In one year, when mating was advanced, presumably due to exceptionally warm weather before mating (yet the temporal abundance of larvae was unchanged), breeding success was higher than in years when mating occurred later.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Tor Erik Brandrud Harald Bratli Anne Sverdrup-ThygesonSammendrag
Det er ikke registrert sammendrag