Question:To what extent is restoration of vegetation in coastal grasslands delayed by accumulation of nutrients after abandonment of traditional management and subsequent reed encroachment? How does nutrient flow in the plantsoil system react to reintroduction of grazing?Location: Coast of Baltic Sea, western Estonia.Methods: Abandoned, continuously managed and restored coastal meadows were selected in four different study regions and their vegetation composition sampled. Nitrogen, P, K, Na, Ca and Mg concentrations and C/N ratios were determined in both vegetation and soil. Differences between management groups were evaluated.Results: Comparison among different management groups revealed several differences in both relative and total amount of nutrients in soil and vegetation. Most soil properties of restored sites were similar to those in abandoned sites. Carbon stock in the soil profile doubled after abandonment, total N concentration in the top soil layer increased while plant available P concentration decreased. The phytomass and chemical composition of phytomass rapidly changed back to a 'normal' level after restoration. Species composition remained different, but species typical of coastal grasslands were present in restored sites. There was a strong site specificity in the results.Conclusions: Re-establishment of grazing had a rapid impact on plant biomass of coastal grasslands. Species composition responded more slowly, but target species returned relatively quickly. Slow recovery of soil properties, however, means that the results of restoration may be fragile and return of tall-growth vegetation is very probable if managent intensity declines. Long restoration periods should be planned to reach pre-abandonment environmental conditions when using non-destructive restoration methods.

The soil organic carbon (SOC) stocks (Mg ha -1 ) of automorphic mineral (9 soil groups), hydromorphic mineral (7), and lowland organic soils (4) are given for the soil cover or solum layer as a whole and also for its epipedon (topsoil) layer. The SOC stocks for forest, arable lands, and grasslands and for the entire Estonian soil cover were calculated on the basis of the mean SOC stock and distribution area of the respective soil type. In the Estonian soil cover (42 400 km 2 ), a total of 593.8 ± 36.9 Tg of SOC is retained, with 64.9% (385.3 ± 27.5 Tg) in the epipedon layer (O, H, and A horizons) and 35.1% in the subsoil (B and E horizons). The pedo-ecological regularities of SOC retention in soils are analysed against the background of the Estonian soil ordination net.

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In grassland areas where herbage production has no economic value, the cut grass is often left on the sward surface where its decomposition is influenced by weather conditions. Although the influence of temperature and humidity on decomposition has been investigated under controlled lab conditions, experimentation has generally been under ideal moisture conditions that have not tested the combinations of climatic limitations that might occur in the field. The decomposition of mown turfgrass clippings deposited at different times of vegetation period was studied in situ using nylon bags during the first 8 weeks after deposition to investigate the effect of weather conditions (the air temperature, relative humidity, precipitation) on decomposition. Decomposition is the highest in the case of high air humidity and temperature of 108C. Limiting factors for decomposition at temperatures above 108C is the air humidity and below 108C the air temperature. The general tendency was that the rate of decomposition increased with increasing air temperature up to 108C, but with further increases of air temperature the decomposition rate slowed down. Relative air humidity had a variable impact (at the beginning of the decomposition process (weeks 1Á2) the influence was negative, during weeks 3Á8 of the decomposition process the effect was positive), and hence had no generalized relationship with decomposition over the studied decomposition period (weeks 1Á8). The most significant influence of weather conditions on the decomposition rate was recorded directly after cutting. If the cutting was done during hot weather conditions, the material was drying fast and therefore decomposed slowly. Our results indicate that for fast decomposition of clippings it is important to maintain the freshness of material. Lower decomposition rates occurred during conditions of hot and dry weather, and also cooler (temperature near to 08C) weather, and can be compensated as soon as favourable weather arrives.

Decisions regarding forest typology, management and protection are often based on the structures of present-day forests, ignoring their successional history. Forests growing on kames, eskers and various moraine hillocks common in regions with Holocene glaciation are good examples of this approach. In Estonia, these forests locally persist as fragments of continuous primary forest, but usually they are situated on former slash-and-burn areas (bushlands) or reforested agricultural land. Our aim was to elucidate the strength of the effect of long-term land-use history on the present-day vegetation compositions of mature hillock forests and their soil chemistry. It appeared that even the mature secondary hillock forests are still distinct from historically continuous stands in terms of species composition. We discovered connections between stand history and species content in hillock forests as well as transformed soil properties. The carbon and nitrogen contents in the humus horizons of secondary forests are lower while their carbon-nitrogen ratios are higher than in continuous forests. The relationship between vegetation and stand history is demonstrated by the higher proportions of anthropophytic and apophytic species in the herb layer of the secondary forests. The presence of species that are tolerant of anthropogenic impact on the secondary hillock forests floor can also be partly explained by the effect of different species in the tree and shrub layers, gaps in the tree canopy, and the boundary effect caused by the small areas of forest patches, neighboring grasslands or fields. The extinction debt in secondary communities should also be considered.

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The re-cultivation of abandoned areas creates weed control problems. The main problems in these areas are perennial weeds, such as Cirsium arvense L. but this perennial deep-rooted plant may have a beneficial effect on the physical properties of compacted soil. In order to study the effect of C. arvense's root system on soil properties, the field experiment and a survey of arable fields were conducted in Estonia. The soil bulk density and penetration resistance were measured from soils covered by C. arvense or spring barley (Hordeum vulgare L.) on compacted and un-compacted soil. The results showed significantly lower penetration resistance and bulk density underneath C. arvense than under barley in both the field experiment and a field survey on arable soils. The shoot mass of C. arvense was less affected than the shoot mass of barley by soil compaction and was caused by C. arvense's better ability to develop its root system in compacted soil. Wheat yield, on soils affected by C. arvense, was increased by 28% on loose soil and 37% on compacted soil. It may be concluded that in areas affected by deep-rooted weed species, such C. arvense, the soil's physical properties will improve at least in the first two years.