Currently, due to prolonged soil drought, dehydrated peat soils are particularly exposed to subsidence and, as a consequence, even to disappearance from the natural environment, in which they perform many important functions, e.g. storage of organic carbon and water retention. Therefore, predicting of settlement and disappearance processes of these soils is very important issue. This study was conducted to: (1) determine the degree and rate of subsidence of a drained peatland over 40 years, (2) establish the effect of subsidence on the depth of ditches and a watercourse, (3) verify empirical equations describing the subsidence based on field measurements. The work was carried out on fen in Central Poland which was managed as a grassland until around 2000, and then its use was discontinued. Subsidence rate was estimated from measurements of the peat deposit thickness taken in 11 locations in 1978 and 2018. Fourteen empirical equations used for estimating subsidence rate of drained peatlands were selected to verify the calculations against field data. The average subsidence rate of the studied peatland was relativity low (0.62 cm year⁻¹), which may be associated with abandoning of agricultural use for the last 20 years. Loss of peat thickness varied from 5 to 41% and depended rather on drainage intensity than on its initial depth. In general, six from the verified empirical equations were useful in estimating average subsidence rate. Four equations seemed to be the most useful for deeply drained sites. Estimation of the subsidence solely on the basis of time since drainage may be biased.

This study analyzed design depths (t_o), post-subsidence depths (t), shallowing magnitudes (d = t_o − t) and ratio values (d/t) of 12 drainage ditches in a fragment of the drained Solec fen-peat (central Poland) over a period of 47 years between 1967 and 2014. A significant decrease of the designed depth of the ditches t_o was shown, from the average designed value of 0.97 m to their average depth after subsidence, t = 0.71 m. The ratio (d/t) of 0.41, which is associated with the degree of organic matter decomposition, indicated medium degree of peat decomposition. The average values of bank and bottom subsidence of the ditches during the analyzed period, 1967–2014, were 0.43 m and 0.17 m, respectively. The values of the average annual rate of land surface subsidence in the vicinity of the ditches were varied and within the range of 0.09 cm year⁻¹ to 1.70 cm year⁻¹, with an average of 0.92 cm year⁻¹. Two linear empirical equations were proposed to calculate the amount of subsidence and the average annual rate of subsidence of peat soil surface near the drainage ditch route, based on the knowledge of the initial thickness of the peat deposit. The results of calculations using the equations proposed by the authors were compared with calculations of the same parameters using 10 equations published in the literature. The results obtained using the proposed equations were mostly larger than those calculated with literature-published equations.

We aimed to determine the rate of subsidence of a peatland over 133 years since its drainage, and to evaluate the relative contributions of compaction and oxidation to this process. Reliable determination of this proportion is problematic. The results of our calculation were applied to estimate CO2 emissions by two approaches, assuming different oxidation fractions. The surface of the fen was lowered by 47.9 %, i.e. 2.0 cm year-1, of which about 60 % was due to oxidation and 40 % due to compaction. The process was more intense around a peat mining area, where the surface lowering was greater and the ratio of compaction to oxidation was about 30:70. Our results for the share of oxidation were in line with values most often reported in the literature for warm temperate climate zones. Therefore, the method used for assessing it may be considered reliable.

Soil sealing is a threat to soil and its ecosystem services. One of the main drivers of soil sealing is land degradation resulting from the expansion of urban areas, where it leads to such problems as the growing risk of flooding and local inundations, urban heat islands, or water shortages. The article focuses on analyses and quantification of the general degree of soil sealing in 2012–2018 in eight functional urban areas (FUA) in Poland, taking into account their division into the urban core (UC) and the commuting zone (CZ). We used the high resolution layer imperviousness density (HRL IMD) data to quantify soil sealing as well as data on land cover and land use with different spatial resolutions, i.e. from the European Urban Atlas project (UA) and the National Database of Topographic Objects (BDOT10k) to quantify artificial surfaces. The research determined the spatial differentiation of UCs and CZs in terms of the degree of soil sealing. We further observed higher average growth of sealed land in CZs. Quantitative and spatial analyses determined the spatial patterns of soil sealing in the FUA in Poland. Soil sealing intensified from 2012 to 2018. The process should be expected to continue in the coming years in light of the continuous transformation of vegetated areas into artificial ones. The conclusions should be considered valuable for the implementation of the spatial policy concerning sustainable land use and soil protection in suburban areas.

If peatland is left without any restoration treatments after mechanical peat extraction ceases, the process of secondary transformation of peat continues. The resulting changes in peat properties severely impede the recovery of vegetation on cutover peatland. The aim of this study was to assess how secondary transformation of peat affects spontaneous revegetation, and the relative importance of different factors in controlling the re-establishment of raised bog species on previously cutover peat surfaces. The study was conducted on two sectors of a raised bog in southern Poland where peat extraction ended either 20 or 30 years ago. Where the residual peat layer was thin (~ 40 cm or less) and the water table often dropped into the mineral substratum, the development of vascular plants (including trees) was favoured, and this further promoted the secondary transformation of peat. In such locations the vegetation tended towards a pine and birch community. Revegetation by Sphagnum and other raised bog species (Eriophorum vaginatum, Vaccinium uliginosum, Ledum palustre, Oxycoccus palustris) was associated with thicker residual peat and higher water table level which, in turn, were strongly correlated with hydrophysical properties of the soil. A species - environmental factor redundancy analysis (RDA) showed that any single factor (of those considered) was not important in determining the revegetation pattern, because of their intercorrelations. However, water table level appeared to be the most important abiotic factor in determining the degree of soil aeration and, consequently, the stage of secondary transformation attained by the peat.