Åke Rühling

Sorption and retention of heavy metals in the woodland moss Hylocomium splendens (Hebw.) Br. et Sch.

The capacity of Hylocomium splendens to sorb heavy metal ions from dilute solutions was studied. The sorption and retention generally followed the order: Cu, Pb > Ni > Co > Zn, Mn. This order proved valid within a wide range of concentrations and independently whether the ions were supplied in pure or mixed solutions. The capacity of the moss tissues to sorb traces of Cu and Pb in the presence of comparatively large amounts of Ca, K, Mg, and Na was found to be very great. This makes it probable that these ions, supplied with the precipitation, are almost quantitatively sorbed by the moss carpets. A large share of Ni when present in precipitation, will also possibly be sorbed. A natural carpet of Hylocomium splendens showed a continuous uptake of Mn, Fe, and Ca from young to old tissues, whereas the increase in the concentrations of minor heavy metals was balanced by the dry matter decrease through decomposition. The developing and mature mor layer below the moss carpet had not enriched heavy metals above the concentrations of the old moss tissues.

Mosses as biomonitors of atmospheric heavy metal deposition: Spatial patterns and temporal trends in Europe

In recent decades, mosses have been used successfully as biomonitors of atmospheric deposition of heavy metals. Since 1990, the European moss survey has been repeated at five-yearly intervals. Although spatial patterns were metal-specific, in 2005 the lowest concentrations of metals in mosses were generally found in Scandinavia, the Baltic States and northern parts of the UK; the highest concentrations were generally found in Belgium and south-eastern Europe. The recent decline in emission and subsequent deposition of heavy metals across Europe has resulted in a decrease in the heavy metal concentration in mosses for the majority of metals. Since 1990, the concentration in mosses has declined the most for arsenic, cadmium, iron, lead and vanadium (52-72%), followed by copper, nickel and zinc (20-30%), with no significant reduction being observed for mercury (12% since 1995) and chromium (2%). However, temporal trends were country-specific with sometimes increases being found.

Heavy metal pollution and decomposition of spruce needle litter

Comparisons were made on the decomposition rates of different fractions of spruce needle litter from numerous sites around two metal processing industries in central and southeastern Sweden, emitting Cu, Zn, Cd and Ni, and Pb, Ni and Cd, respectively. All measurements were performed under controlled laboratory conditions. At water capacity and 15?C a C02 evolution rate in partly disintegrated litter of ca 0.23 mg C/g dry matter, 24 hr was measured in samples with > 10 prmol Zn + Cu + Cd + Ni per g, compared with ca 0.50 mg C in samples with < 5 jimol/g. Highly significant negative correlations were obtained in all materials between heavy metal concentration and C02 evolution rate or dehydrogenase activity. It is concluded that, in acid forest sites, the general decomposition rate will be depressed even by moderate concentrations of heavy metal ions, at least during those parts of the year when the water supply is adequate.

The mycorrhizal status of plants colonizing a calamine spoil mound in southern Poland

Abstract The arbuscular mycorrhizal (AM) status of two plant communities on a calamine spoil mound (rich in cadmium, lead and zinc) in southern Poland was surveyed: an undisturbed grassland community and an early succession community that developed after complete removal of the surface layer of the calamine substrate about 10 years earlier. The undisturbed site harbored 40 herbaceous species making up 87% of the absolute cover. AM colonization was recorded in 25 species accounting for 77% of the relative cover. Species with 51–75% AM root colonization such as Festuca ovina and Leontodon hispidus dominated the undisturbed turf, contributing 45% to the relative cover. Carex ssp. were the most abundant nonmycorrhizal plants and accounted for 9% of the relative cover. Spores of Glomus aggregatum, G. constrictum, G. fasciculatum, G. pansihalos, Glomus sp. and Entrophospora sp. averaged 25 per 100 g dry substrate at the undisturbed site. The disturbed site was colonized by 25 species accounting for 17% of the absolute cover. Among the AM plants, most abundant were the species with up to 20% AM root colonization, such as Agrostis stolonifera and Thymus pulegioides, wich accounted for 24% of the relative cover. Nonmycorrhizal species, such as Biscutella laevigata,Cardaminopsis arenosa, Gypsophila fastigiata and Silene vulgaris, dominated the early succession community and contributed 64% to the relative cover. Spores of G. fasciculatum and Entrophospora sp. averaged 20 per 100 g dry substrate at the disturbed site.

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (≥ 1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km × 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r(2) = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.

Recent changes in the deposition of heavy metals in northern Europe

Carpet-forming bryophytes (mosses) have been used extensively since the late 1960s in assessing regional and temporal variability of atmospheric heavy-metal deposition. A large-scale decrease in heavy-metal deposition occurred during the 1970s in Sweden, probably also in other parts of northern Europe. The decrease was closely related to known changes in atmospheric emissions.

Regional differences in floristic change in South Swedish oak forests as related to soil chemistry and land use

Abstract. Changes of the ground layer vegetation between1983 and 1993 were studied on permanent oak forest plots inSkane and eastern Smaland, two regions of South Sweden richin oak but with different climatic conditions. 79 of the 123more common species differed considerably in frequencybetween Skane and Smaland. The oak forests in Skane con-tained more typical forest species, whereas the number oflight-demanding grassland species was higher in Smaland.Almost half of the more common species showed significantchanges in frequency between 1983 and 1993. Several speciesof clearings and some light-demanding grassland species in-creased their frequency in Skane. They were probably fa-voured by canopy thinning which occurred in 65 out of 95permanent plots. Only two species decreased in frequency inSkane, but 14 species showed a decrease in Smaland. All weretypical grassland species and their decline may be regarded asa long-term response to ceased grazing and tree canopy clo-sure as almost no tree cutting occurred during the study periodin Smaland. Total species richness increased with manage-ment intensity in Skane. This was due to decreasing specieslosses and increasing establishment of new species at intensemanagement. A small general increase in species numberswas recorded in Smaland. Species richness was more closelyrelated to soil pH in Skane than in Smaland. The floristicvariability between the oak forest plots was closely related tosoil pH in both Skane and Smaland. We suggest that changesof light conditions as a result of changes in forest managementare important for current secondary succession in South Swed-ish oak forests, whereas the general floristic pattern is to alarge extent controlled by soil acidity.Keywords: Detrended Correspondence Analysis; Forest man-agement; Ground layer vegetation; Secondary succession;Soil acidity; Species richness.Nomenclature: Lid (1987).

Soil Acidification and Metal Solubility in Forests of Southern Sweden

Far-reaching acidification of forest soils has occurred in southern Sweden during the last decades. The decreasing pH has, directly or indirectly, increased the solubility of several elements in the soil, including magnesium, aluminum, cadmium and zinc. This has resulted in high concentrations of these elements in the soil-water and a considerably greater output than input from the forest ecosystems. Both deciduous and coniferous forest soils have become acidified but the solubilization and flow of metals is greater in spruce stands than in beech and birch stands on originally similar soil.

Country-specific correlations across Europe between modelled atmospheric cadmium and lead deposition and concentrations in mosses

Previous analyses at the European scale have shown that cadmium and lead concentrations in mosses are primarily determined by the total deposition of these metals. Further analyses in the current study show that Spearman rank correlations between the concentration in mosses and the deposition modelled by the European Monitoring and Evaluation Programme (EMEP) are country and metal-specific. Significant positive correlations were found for about two thirds or more of the participating countries in 1990, 1995, 2000 and 2005 (except for Cd in 1990). Correlations were often not significant and sometimes negative in countries where mosses were only sampled in a relatively small number of EMEP grids. Correlations frequently improved when only data for EMEP grids with at least three moss sampling sites per grid were included. It was concluded that spatial patterns and temporal trends agree reasonably well between lead and cadmium concentrations in mosses and modelled atmospheric deposition.

Chemical and biological effects of artificially increased nitrogen deposition to the ground in a Swedish beech forest

During 1985–90, effects of N deposition to a beech forest floor in south Sweden were studied by supplying 12 and 36 kg N ha‐1, as NH4NO3, on 25 occasions, i.e. 60 and 180 kg ha‐1 yr‐1, corresponding to ca. 3 and 9 times the ambient deposition rate. Treatments raised the output of NO‐ 3 and several base and metal cations from the soil. There was some increase in the total N content of the leaves and a considerable increase in the contents of free amino acids, whereas phenols decreased. Leaf concentrations of Ca, P and K were lower than in controls. Throughfall chemistry was generally little influenced by the treatments. There was no measurable change in the wood production. Fruitbody production of ectomycorrhizal fungi almost ceased, whereas that of major decomposer species increased considerably. The biomass of most field layer species was reduced to some extent in the treated plots and no new vascular plant species appeared during this five‐year period as a result of the treatments.