Next to global warming, excessive deposition of nitrogen has an alarming environmental impact on forest ecology, especially within dioecious species. Resource availability affects seed quality and can affect the distribution of plant species. Lower seed productivity can also be a result of limited pollen availability or lower pollen quality. A few studies have assessed the effect of nutrient availability on the quantity and quality of pollen grains produced. Therefore, rooted shoots of dioecious, male Juniperus communis L. grown in different nutritional conditions were used to assess the impact on productivity and quality attributes of produced pollen grains (pollen volume, morphology, germination, and chemical composition). The results indicated that nutrient availability impacts pollen grain development. Male plants growing in nutrient-rich environments appear to compensate for the lower quality of produced pollen grains by producing a higher number of male cones and thus a greater quantity of pollen. In contrast, the opposite was observed in plants growing in nutrient-poor environments. The availability of nitrogen and other nutrients will probably continue to impact soils in the foreseeable future due to anthropogenic activity and can be one of the drivers that can impact the reproduction and distribution of plants.

• Key message: Natural regeneration ofP. abies(L.) H. Karst. may reach high densities in lower mountain elevations. The highest densities were found in sites with moderate light availability, with low pH, and not near the riverbank. However, age-height classes differed in the predicted magnitude of response, but were consistent in response directions. Mosses and understory species typical of coniferous forests were positively correlated with regeneration density.•Context: Norway sprucePicea abies(L.) H. Karst. in Central Europe is at risk under climate change scenarios, particularly in mountain regions. Little is known about the impact of environmental factors on the natural regeneration ofP. abiesin low-elevation mountain forests.•Aims: We aimed to assess impacts of distance from the riverbank, soil pH, and light availability on naturalP. abiesregeneration. We hypothesized that (1) naturalP. abiesregeneration would depend on light availability and soil pH and (2) there are understory plant species which may indicate the microsites suitable for natural regeneration ofP. abies.•Methods: The study was conducted in the Stołowe Mountains National Park (SW Poland, 600–800 m a.s.l.). We established 160 study plots (25 m²) for natural regeneration, light availability, soil pH, and understory vegetation assessment.•Results: The highest densities of natural regeneration ofP. abieswere observed in sites with moderate light availability (0.1–0.2 of open sky) and low pH (3.5–4.5), and located relatively far from the riverbank. Cover of 22 understory plant species were correlated with naturalP. abiesregeneration densities, mostly positively.•Conclusion: Different stages of natural regeneration ofP. abiesrevealed different regeneration niches. Most understory plant species (bryophytes and herbs typical of coniferous forests) do not compete with natural regeneration ofP. abies.

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.

Key message: We identified the effect of microclimatic conditions on soil mite communities (Mesostigmata) during the decomposition of broadleaved and coniferous litter. The abundance, species richness, and diversity of mite communities decreased from spring to autumn regardless of litter quality and was related to changes in temperature and precipitation. Context: Litter decomposition is one of the fundamental soil-supporting processes in terrestrial ecosystems. However, there is still a lack of knowledge on some general patterns of the relationships between litter quality (tree species), microclimate, and structure of soil mite assemblages. Aims: The study aimed to analyze the impact of climatic conditions (temperature and precipitation) on mesostigmatid mite communities in the litter of 11 tree species through the vegetation season. Methods: The experiment tested litter decomposition of 11 different tree species (693 litterbags), for seven consecutive months (April-October) under homogenous Scots pine (Pinus sylvestris L.) canopy monocultures in common garden conditions. Soil mites were extracted in Tullgren funnels. Results: Mesostigmatid mite abundance was positively correlated with the temperature of the sampling month and negatively with the temperature of the previous month. Species richness depended on the sampling month temperature. Changes in litter mass loss in late autumn (after litterfall) and overwinter were important for colonization of litterbags by soil mesostigmatid mites in the following spring. Conclusions: Changes in climatic conditions, i.e., temperature and precipitation between the sampling months (during the following vegetation period), may cause significant changes in mesostigmatid mite abundance and thus may impact ecosystem functions. The winter period is important for mesostigmatid mite abundance in the following vegetation period.