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This article discusses phytoremediation of heavy metal polluted forests using recycled organic matter and native woody plants in Finland. According to the authors, spreading a mulch cover (a mixture of household biocompost and woodchips) on the soil surface resulted in recolonization of natural vegetation. Tree species had higher survival rates, but the dwarf shrubs covered a larger area of the soil surface. Planting of dwarf shrubs and tree seedlings was successful and Empetrum nigrum and Pinus sylvestris especially proved to be suitable species for revegetation. They concluded that low-cost mulching materials are suitable for restoring heavy metal-polluted soil.

Understorey vegetation of Scots pine forests was studied along a 8-km transect running SE from a Cu/Ni smelter at Harjavalta, SW Finland.Long-term accumulation of heavy metals and sulphur in the forest ecosystem has drastically changed plant communities. Vegetation was almost absent up to a distance of 0.5 km from the smelter. The total coverage and the number of plant species increased with increasing distance from the smelter. Ordination by global non-metric multidimensionalscaling (GNMDS) indicated that the floristic composition was differentiated in response to the pollution level. The main compositional gradient of GNMDS was correlated with the heavy metal concentrations inthe organic soil layer and with the size of the overstorey trees. Vascular plants were more pollution-resistant than ground lichens, whereas mosses were the most sensitive plant group. In addition to heavy metals, nutrient imbalances and the considerably reduced water-holding capacity of the surface soil also restrict plant recolonisation on the degraded sites. [ABSTRACT FROM AUTHOR]

Small-scale element distribution in soil/plant-systems in patches ofEmpetrum nigrum (microsites) at heavy metal contaminated sites located 0.5 and 4 km from the copper/nickel smelter at Harjavalta was investigated. The Cu concentrations of E. nigrum varied between 12 and 2300 mg/kg dw and showed increasing accumulation with increasing tissueage. Stems contained more Cu than leaves of the same age. The distribution pattern of Ni and Pb in the above-ground biomass followed thatof Cu. Roots contained relatively low concentrations of all airborneheavy metals. In the soil, the highest concentrations of total Cu occurred in the humus (Oh) layer: on average 49,450 mg/kg dw at 0.5 km distance and 12,025 mg/kg dw at 4.0 km. Despite the extremely high Cuconcentrations in the topsoil, the concentrations in the mineral soil below a depth of 10 cm did not exceed 2.5 mg/kg dw at any site. [ABSTRACT FROM AUTHOR]

The Cu and Ni tolerance of 3- to 5-year-old cuttings of crowberry (Empetrum nigrum) were tested in controlled conditions. Six levels of Cu (0.1/100 mg l-1), five levels of Ni (0/100 mg l-1) and nine levels of Cu+Ni were applied. The elongation of the shoots, new shoot and root dry weights indicated an adverse effect of increasing Cu and Ni concentrations. At low Cu levels the addition of Ni decreased the dry weights more than at high Cu levels. The resultsshow that E. nigrum accumulated high concentrations of Cu and Ni mainly in old stem tissue, which contained a maximum of over 3000 mg kg-1 Cu and 1000 mg kg-1 Ni. The concentrations ofCu and Ni in E. nigrum were higher than those measured in plants growing in areas near to Cu/Ni smelters, but the accumulation pattern was similar. The survival of the cuttings was not affected suggesting that E. nigrum possesses an internal heavy metal tolerance. [ABSTRACT FROM AUTHOR]

The copper (Cu) resistance of 1-year-old seedlings of heather (Calluna vulgaris) was tested in a greenhouse experiment. The plant material originated from seeds collected from three peatland sites located 1.2 km to the NW, and 2.5 and 5.5 km to the NE of the Harjavalta Cu/nickel (Ni) smelter, SW Finland. The plants were watered with a nutrient solution containing five different levels of Cu (1, 10, 22, 46 and 100 mg l-1). Cu clearly decreased the length growth of shoots, shoot and root biomass of C. vulgaris. More than 50% of the seedlings exposed to the highest Cu treatment died. C. vulgaris accumulated high amounts of Cu, the living old roots containing a maximum of 2200 mg kg-1 Cu and the living stems 1300 mg kg-1 Cu. Discolouring leaves contained higher Cu concentrations than green leaves. The results indicate Cu accumulation in roots and root-to-shoot transport. Some differences were found between the responses ofthe three seed provenances, but none of the populations proved to bemore resistant to Cu than the others in all the measured responses. [ABSTRACT FROM AUTHOR]

The state of health of 30 Norway spruce (Picea abies L. Karst.) stands located on the uplifting coast of western Finland was examined in 1992. Relationships between crown condition, elemental concentrationsof the needles, organic layer properties and soil type were studied using sitewise data. The site scores along the first axis of the Principal Component Analysis for certain needle and organic layer variables were used as the site fertility index. The spruces in the study area showed a higher level of defoliation and this occurred in younger stands than elsewhere in southern Finland. Defoliation and discoloration correlated positively with stand age, and negatively with the site fertility index. Low N and Cu concentrations of the needles were found in older stands where spruces were highly defoliated and discolored. Boron concentrations of the needles were highest in these stands.Total N of organic layer and extractable S concentrations were negatively correlated with stand age, defoliation and discoloration. The results suggest that poor crown condition of the coastal spruce standsis related to natural soil factors such as periodic water-logging and low fertility. Long-lasting soil frost as a consequence of thin snow cover might be an additional stress factor impeding water and mineral nutrient uptake in the beginning of the growing season. [ABSTRACT FROM AUTHOR]