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Abstract. An integrated multidisciplinary approach including descriptive and experimental research of environmental and biotic factors was used to evaluate an attempt to restore a species‐rich fen meadow, phytosociologically belonging to the Cirsio‐Molinietum. Expert judgement and preliminary research indicated that soil acidification, due to drainage in the surrounding area, caused the degeneration of the fen meadow. Flooding the meadow with surface water was applied in order to stop acidification. A small irrigated wetland (helophyte filter) was constructed to reduce nutrient availability in the surface water. Sod cutting was applied in a small area as well. The two measures were evaluated through: (1) measurements of hydrological and soil factors, (2) seed bank analysis, (3) recording species composition in permanent plots, (4) assessing the type and extent of nutrient limitation using a full‐factorial fertilization experiment, (5) assessing the effect of liming on vegetation biomass, and (6) recording the growth of three introduced fen meadow species in the liming experiment. The research was carried out in a degraded site with intact vegetation, a degraded site where the top soil was removed by sod cutting and a reference site with intact Cirsio‐Molinietum vegetation. Groundwater levels in the degraded and the stripped site differed slightly from those of the reference site but they were within the range of Cirsio‐Molinietum requirements. Groundwater quality slightly improved in the stripped site. Top‐soil removal considerably reduced the macro‐nutrient contents and caused a stronger P‐deficiency. No increase in soil pH was observed immediately after top‐soil removal. A small increase in soil pH was found after five years in the stripped site, indicating a slight recovery from acidification. Liming after top‐soil removal had little effect on the soil pH after six months but stimulated the growth of established species such as Agrostis canina. Few viable seeds of characteristic fen meadow species were present in the seed banks of both degraded and well developed fen meadow sites. The species composition after top soil removal reflected the seed bank of the degraded fen meadow and establishment of characteristic fen meadow species was poor, even after five years. The introduced species (Carex hostiana, C. panicea, Cirsium dissectum) survived during the first year in both the degraded and the stripped site. Liming initially stimulated the growth of two species, but in the second year this effect disappeared. After two years, none of the introduced species survived at the stripped site. The restoration measures failed so far, probably because acidification could not be counteracted satisfactorily. Finally, it was concluded that our multidisciplinary approach enables us to draw proper conclusions and that it is suitable for other restoration attempts as well.

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A main limitation of pixel-based vegetation indices or reflectance values for estimating above-ground biomass is that they do not consider the mixed spectral components on the earth's surface covered by a pixel. In this research, we decomposed mixed reflectance in each pixel before developing models to achieve higher accuracy in above-ground biomass estimation. Spectral mixture analysis was applied to decompose the mixed spectral components of Landsat-7 ETMþ imagery into fractional images. Afterwards, regression models were developed by integrating training data and fraction images. The results showed that the spectral mixture analysis improved the accuracy of biomass estimation of Dipterocarp forests. When applied to the independent validation data set, the model based on the vegetation fraction reduced 5-16% the root mean square error compared to the models using a single band 4 or 5, multiple bands 4, 5, 7 and all non-thermal bands of Landsat ETMþ.

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SUMMARY Two fen peat soils, supporting a species‐rich fen vegetation with a high nature value, and two accompanying drained fen peat soils, supporting vegetation types with a low nature value, were subjected to a study on nutrient deficiency. This study tested what effect rewetting of drained fen peat soils had on the nutrient deficiency. In each of the study areas, soil was collected from the wet site and from a neighbouring drained site. Holcus lanatus was used as a phytometer screening the wet soil under wet conditions and the drained soil when drained or rewetted. The soil taken from the wet site revealed a higher yield than the soil from the drained site in both study areas. Additional supply of K, in combination with N or P supply, further increased the biomass yield. K‐deficiency was even stronger in the drained site of both study areas. Experimental rewetting did not entirely remove this deficiency and additionally enhanced N‐deficiency. The results from this phytometer approach are discussed as related to results from field and laboratory experiments with vegetation as object of research.