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Mites significantly contribute, prevalently by vertical movement, to mixing of the organic layer with the mineral soil, thus they may be important in renewing soils. Our aim was to analyze the changes in abundance and species richness of mesostigmatid assemblages on decomposing leaves of Alnus glutinosa (L.) Gaertn., Betula pendula Roth, Pinus sylvestris L. and Quercus robur L. in pine and birch stands growing on a reclaimed spoil heap and adjacent forests. In December 2013, 1024 litterbags (mesh size = 1 mm) containing leaf litter of broadleaved and coniferous trees (mean initial dry weight per sample = 5.789 g) were laid out in the same number and kind in each of the two sites. Mites were extracted from litterbags which were collected every 3–6 months for 3 years. In total, 6466 mites were identified in 59 taxa. Total abundance was higher on forest habitats (5174 specimens) compared to the spoil (1292), and in birch compared to pine stands, both in forest (3345, 1829, respectively) and spoil habitats (981, 311). Throughout the experiment, mites were most abundant on oak litter samples (2063 specimens), while the remaining litter types had similar abundances (1455–1482). At the beginning of the experiment (3–6 months) mite abundance was very low, but was higher on forest habitats. The highest abundance was found after 9 months—144 specimens in pine stands on the spoil heap and 685 in birch stands on forest habitats. During the study, 49 taxa were found on forest and 29 on heap habitats. In birch stands, 37 and 22 taxa were found, whereas in pine 30 and 21, on forest and heap, respectively. The most frequent species on the heap were Amblyseius tubae Karg, Asca bicornis Canestrini et Fanzago, and Asca aphidioides Linneaeus, whereas in forest habitat—Zercon peltatus C.L. Koch, Veigaia nemorensis C.L. Koch, and Trachytes aegrota C.L. Koch. Habitat conditions, tree species and litter type significantly determined the mesostigmatid species composition, richness and abundance. By selection of dominant tree species during afforestation, it is possible to significantly affect the soil fauna composition, and thus indirectly the rate of decomposition.

No in‐depth studies covering litter decomposition were previously conducted on afforested postmining sites despite the importance of litter decomposition on soil formation, especially in degraded areas. We aimed to compare leaf litter decomposition rates of 14 tree species growing in mixed stands on a postmining spoil heap, and to compare their decay rates with those obtained in pure stands of tree species that are very often planted in postmining areas. The study was conducted on the Bełchatów Lignite Mine spoil heap, central Poland. We studied litter decomposition rates over 5 years using the litterbag method. Leaf litter decomposition rates (k constants; yr−1) after 5 years of the experiment were arranged from highest to lowest as follows: Prunus serotina (1.04), Alnus glutinosa (0.86), Fraxinus excelsior (0.81), Ulmus laevis (0.73), Acer pseudoplatanus (0.68), Populus tremula (0.63), Populus × canadensis (0.59), Betula pendula (0.54), Populus nigra ‘Italica’ (0.38), Quercus rubra (0.36), Pinus sylvestris (0.34), Robinia pseudoacacia (0.34), Fagus sylvatica (0.25), and Quercus robur (0.22). Decomposition rates increased with Mg, Ca, and summed Mg + Ca + P + K contents in freshly fallen leaves (%). All species‐specific decomposition rates were higher in mixed than in Scots pine stands. Half of them were also higher than in pure stands of other tree species. Our results indicate that tree species composition could significantly affect the physiochemical properties of upper soil horizons on reclaimed areas. Based on these findings, we recommend planting high share of not only A. pseudoplatanus, A. glutinosa, and U. laevis but also F. sylvatica and Q. robur in stands on postmining spoil heaps, because mixed stands can accelerate soil development more than pure stands.

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Abstract:It is not clear to what extent trees growing on anthropogenic sites change their growth and biomass allocation to different organs. We assessed the aboveground biomass in a chronosequence of six Scots pine monocultures (between 6 and 20 years old) to examine how precisely the site-specific or control allometric equations may reflect the value of biomass accumulation and allocation in stands growing in harsh site conditions on the overlayer spoil heap made as a result of opencast brown coal mining. The site is characterized by poor edaphic and water conditions and nutrient deficiency. The control equations were developed from Scots pine stands growing on post-agricultural lands in the close vicinity of the spoil heap. We found that equation type significantly influenced results of predicted biomass accumulation for all biomass components studied (although results were only marginally significant for total aboveground biomass, P=0.08). Total aboveground biomass in younger stands (6-9 years old) estimated using site-specific equations was >40% higher and for older stands (17-20 years old) from 7 to 27% lower than estimated using equations developed for the control sites. Our study revealed that under harsh environmental conditions in spoil heaps, biomass of young Scots pine stands significantly differ from values calculated based on control equations developed for more fertile soils with better water conditions in the same region. The control biomass equations may not be suitable to estimate biomass accumulation in stands growing on infertile habitats with poor water conditions, if the control equations are developed for nearby stands but growing under better site conditions.

Aim Information about the importance of propagule pressure and habitat invasibility in invasion success of dispersal‐limited species is scarce. We aimed to assess invasiveness of Quercus rubra within stands of 14 tree species, and the effects of distance from propagule source on invasion success, to highlight limiting factors for further application in nature conservation. Location Siemianice Experimental Forest—a common garden forest experiment with 14 tree species, western Poland. Methods We investigated aboveground biomass, leaf area index and density of Q. rubra natural regeneration within 53 experimental plots, as well as distance from the seed source. We also analysed light availability changes between 2005 and 2015 on plots of each tree species. We used multiple linear regression and variable importance to quantify the effect of each factor. Results All factors tested influenced ecological success of Q. rubra. Invasion success decreased with increasing distance from the seed source and decreasing light availability and was higher within stands of pioneer tree species. Leaf area index depended mostly on tree stand species, density depended on distance from the propagule source and biomass depended on both. Light availability explained 7.2%–30.2% of the variance; tree species—from 36.1% to 57.4%; and distance from the propagule source—from 12.4% to 56.7%. Main conclusions Tree stand species, light availability and distance from the propagule source influence ecological success of invasive Q. rubra, displaying their importance for spread of this species. These factors are controllable in forest/conservation management and may be used to prevent Q. rubra invasion. Planting late‐successional tree species that cast dense shade, maintaining canopy closure and removing fruiting trees from surrounding more invasible stands may prevent Q. rubra invasion.