S. Löfgren, 1 (ed.), M. Aastrup2, L. Bringrnark1, S. Bråkenhielm1, H. Hultberg3, K Johansson, K Kindbom3, H. Kvarnäs1, L. Lundin’
‘Department of Environmental Assessment, SLU, Box 7050, SE-750 07 Uppsala, Sweden. e-mail: lars.lundin@ma.slu.se
2Geological Survey of Sweden, SGU, Box 670, SE-751 28 Uppsala, Sweden.
‘Swedish Environmental Research Institute, Box 47086, SE-402 58 Gothenburg, Sweden.
A report of Swedish integrated monitoring in 1998 reports from the three IM-sites Gårdsjön, Aneboda and Kindia. The results are summarised along with some highlights from the results of the year. The report is in Swedish and the enfire set of results is included in appendixes at the end of the report.
The weather in 1998 was characterised by a warm beginning of the year, resulting in water runoff peaks m January and Februaiy atboth Gårdsjön and Kindia.
The period June-August showed very low temperatures and large amounts of predpita%on. This formed discharge peaks also during the summer months and the streamflows never ceased. Ali streams showed peak ftows in Octobei caused by heavy rains and almost saturated soils.
The stream water in the IM areas had low iomc strength, chronic acidity and relatively high aluminium concentrations. With the excepfion of lead, other heavy metais showed concentrafions below the leveis where biological effects on the biota can be expected in streams. These limits were frequently surpassed in soil and groundwater. The concentrations of inorganic nitrogen and phosphorus were low in ali areas. The proximity to the sea influenced the chemistry at Gårdsjön, while the high concentrations of organic matter were important at Aneboda. A special study at Kindia showed that the runoff chemistry was strongly influenced by rapid groundwater flows in the upper soil layers of the soils closest to the stream immediately before it entered the stream. This is believed to be a widespread feature of small forested catchments in Sweden.
At Kindia, the analysis of sffica showed that superfidal, near stream (several meters) groundwater, which had little contact with minerogenic material, dominated the fiow to the stream. It also showed that the weathering of aibite was intense close to or in the discharge area. The latter gave the stream water its composition with regard to base cations. furthermore, the sffica values demonstrated ffiat the spatial origin of the water within the drainage basin is important for the runoff chemistry.
During the Aneboda campaign 1996-97, inorganic aluminium (A11) was analysed in water from different media. A11 originates from the soil minerais and is dissolved at add condffions (pH<4.5). In the central part of the Aneboda catchment, the soil solufion was acid and A11 dissolved. In upper as well as lower parts of the basin, the soil profiles were less add and the A11 dissolufion less pronounced. In the stream, pH decreased again, but the mobilisation of A11 was lower than in the soils.
Critically low Ca/A11 molar rafios (<1) occurred in the B-horizons, indicating risks for forest dedine. However, the biological observaffons showed patterns of defoliafion and discolouration of tree crowns that were normal for the region.
During 1998, the outflow of sulphate exceeded the inflow 2-3 timesin ali three catchments. The results from 1997 and 199$ show that compared to ffiroughfali, large amounts of sulphate were released to the soil water from the humus layer in both recharge and discharge areas. This indicates that the main part of this sulphur has another origin than sulphate adsorbed in the B-horizon and that it originates
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from organic matter. It is likely that mineralization and oxidation of organically bound sulphur in the humus layer formed the sulphate. If this condusion is correct, it should have consequences for the interpretation of how the high sulphur deposition during the last decades has affected the pooi of exchangeable sulphur in the soils. Therefore, the sulphur dynamics in soils ought to be studied in more detail.
The decomposition in field of standardised litter has beenstudied since 1983.
The measurements show that material exposed at locals in southern Sweden (Aneboda, Härsvatten/Gårdsjön, Grimsö/Kindla) decomposed similarly, with a weight loss of 30-35% the first year, followed by a dedining weight loss down to 7-12% the third year. At Reivo in northern Sweden, a slower weight loss was documented from23% the first year to 14% the third year. Regardless of the long and cold winter at Reivo, the weight loss was larger than in southern Sweden the third year. Possible explanations for the different kinetics in northern and southern Sweden can be that pollution and/or milder winter climate yields a more resistant, ligmn contairnng debris in southern Sweden.
The pollution load is relatively low at the IM sites and vegetafion changes are not to be expected except as after a long period oftime.Even if no trends can be documented at the Swedish vegetation plots, the studies fuifil the purpose of bemg references to the more heavily polluted IM sites in central and Eastern Europe. As yet, the only significant trend is a decreased vegetafion cover at Gårdsjön, which is probably caused by increased trampling at the piot.
At Gårdsjön, the amount of algae on Norway spruce needies has slightly decreased and thetimefor colonisafion somewhat increased. Such changes are to be expected ff the deposifion of nitrogen decreases, which might be the case.
Regarding epiphytic lichens, Aneboda had the highest sensitivity index (3.8), Gårdsjön lower (2.1) and Kindia the lowest (2.0). Kindia should have had the highest and Gårdsjön the lowest values if only the sulphur deposition was considered (approximately 6,5 and 4 kg SO4 ha1 a4, respectively). However, local condffions in the tree stands, e.g. differences in tree spedes and tree density, are more important than the sulphur deposition. Thetimeseries ftom each site respond on changes in sulphur deposition, however.
Defoliation, i.e. the amount of needies that are missing compared to an ideal status when ail needies are present, was approximately 20% for Norway spruce at ali three IM sites. This level is normal m forests subjected to forestry. At the IM sites, the trees are ageing anddying,and an even larger defoliation should be considered normaL
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