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Soil mite communities structure (Acari, Mesostigmata) during litter decomposition of seven tree species in pure Scots pine stands (Pinus sylvestris L.) growing on a reclaimed post‐industrial area
AbstractOur knowledge about mites, including mesostigmatids, compared to their significant role in soil‐forming processes on post‐industrial areas, is currently insufficient. Therefore, our study aim was to analyze the succession of mesostigmatid communities in relation to litter decomposition of seven tree species [Acer pseudoplatanusL.,Alnus glutinosa(L.) Gaertn.,Fagus sylvaticaL.,Pinus sylvestrisL.,Prunus serotinaEhrh.,Quercus rubraL.,Robinia pseudoacaciaL.] in pure Scots pine stands growing on a reclaimed spoil heap. In December 2011, 1439 litterbags were placed on plots and collected after ca. 3, 6, 9, 13, 19, 25, 31, 37 months since the experiment started. In total, we recorded 9653 mites classified into 67 taxa. The mesostigmatid abundance was affected by percentage initial litter mass loss. Interestingly, litter type shaped species richness and diversity, but not abundance. The highest abundance, almost two‐times higher compared to other tree species, was recorded inPrunus serotinalitter (352.73 ± 105.22 ind.; calculated per 100 g of dry litter mass) and the lowest inQuercus rubra(81.23 ± 9.82 ind.). Furthermore, the lowest richness (2.39 ± 0.07; calculated per sample) and diversity (0.33 ± 0.02; calculated per sample) was recorded inPinus sylvestrislitter, therefore, our results are in contradiction to the home‐field advantage assumptions that the ‘home’ litter has a positive effect on soil fauna structure compared to the ‘foreign’ litter. Nevertheless, the greatest abundance share ofAsca bicornisandAmblyseius tubae, the most numerous species, was recorded forPinus sylvestrislitter.
Diversity of soil mites (Acari: Mesostigmata) in streamside mountain forests
AbstractHabitat loss and fragmentation are among the most influential factors responsible for recent biodiversity decline. The key to understanding the changes in ecosystem functioning is the analysis of the relationship between species diversity and environmental gradients such as those found near streamside forests. We used soil mites (Mesostigmata) as model species as they are predators in soil ecosystems, they occur in high relative abundance, their communities are species‐rich and are robust toward sampling and extraction methods. The main goals of this study were to (1) check how the plant community and associated environmental variables (light conditions, litter accumulation, and soil acidity) along mountain streams affect soil Mesostigmata abundance and diversity, and (2) to analyze the distance from mountain streams to which the ecosystem functions (Mesostigmata diversity) are affected, based on a distance gradient. We systematically established 31 study plots (500 m2) every 200 m along the watercourses, representing three habitat types along the stand composition gradient (ash‐sycamore [Fraxinus excelsior–Acer pseudoplatanus], European beech [Fagus sylvatica], and Norway spruce [Picea abies] forests) for measurements of soil litter thickness, soil acidity, and light conditions. We extracted soil Mesostigmata mites from samples in Tullgren funnels and identified them to the species level. We found that Mesostigmata abundance in forests decreased in the following order: Norway spruce forest > European beech forest > ash‐sycamore forest. Additionally, changes in Shannon diversity were associated with light conditions. In conclusion, streamside mountain forests maintained abundant, diverse and species‐rich Mesostigmata communities, which were associated with a plant community‐light condition gradient. Additionally, more abundant mite communities occurred in forests with higher soil pH values, and under higher light conditions.
×Sorbaronia ′Mitschurinii′ - an overlooked alien shrub rapidly expands in temperate Scots pine forests
Abstract Biological invasions are one of the most important threats to biodiversity. However, spread mechanisms have been described in detail only for some widespread taxa. Here, we aim to characterize the unique phenomenon of ×Sorbaronia ′Mitschurinii′ (Rosaceae) spread into temperate Scots pine forests. We assessed the surroundings of an abandoned ×Sorbaronia ′Mitschurinii′ plantation, established in 1986 near Ośno Lubuskie (W Poland). Around the plantation we established 66 study plots in 30 m intervals along eight transects, in a systematic design. Using generalized linear mixed-effects models we analysed how the distance from the propagule source (i.e. abandoned plantation), maximum age of ×Sorbaronia shrubs assessed using dendrochronological techniques, and light availability determined the density and biomass of the studied plant. We found that its mean aboveground biomass in the plantation was 7.22 ± 0.66 Mg ha−1, and decreased with distance from the propagule source: 6.83 Mg ha−1 30 m from the abandoned plantation, 1.38 Mg ha−1 at a distance of 90 m, and 0.11 Mg ha−1 at a distance of 180 m, almost disappearing at further distances (but present at the maximum distance of 450 m). The density and aboveground biomass of ×Sorbaronia ′Mitschurinii′ increased with increasing maximal age of the studied plant and its light availability. The ×Sorbaronia ′Mitschurinii′ plantation acted as a strong propagule source, as it reached a density of 100 ind. 100 m−2 after five years, forming a dense shrub layer, capable of reproducing. We conclude that alien species planted at high density and left with no management control might transform into invasion hotspots under favourable circumstances. The study highlights the importance of scientific awareness of similar cases of overlooked invasion sources, as management to limit their spread is still possible.