Вплив зімкненості крон дерев і покриття трав’янистих рослин на структуру підстилкової мезофауни широколистяних лісів степової зони України
The count of litter macrofauna was carried out in 339 natural deciduous forest sites in Dnipropetrovsk, Zaporizhzhya, Nikolaev and Donetsk regions of Ukrainein 2001–2014. It was shown that tree crown density did not significantly influence the abundance of litter macrofauna and the abundance of litter invertebrates. The Shannon and Pielou diversity indexes have a tendency to raise the gradient of tree crown density (from 50% to 90–100%). The relative abundance of saprophages and zoophages reached its minimum (median was 18% and 3%, respectively) in forest sites with sparse crown cover, and, at the level of tendency, was higher in dense forests with a closed crown (median was 40% and 18%, respectively). The relative abundance of polyphages, on the contrary, was lower in these conditions (82% in sparse and 27% in closed crown cover). The number of species in each trophic group did not significantly change in relation to tree crown density. At sites with 70–79% tree crown density the size structure of the litter macrofauna was close to its optimal condition. The relative abundance of ants reached its maximum (median 73%) in sparsely timbered sites (up to 50% tree crown density), the relative share of Isopoda reached its maximum (median 40%) at sites with average crown density (50–59%). At densely wooded sites the taxonomic structure at the level of order and family was more or less level, without clearly dominant groups, each order and family occupying about 15% of the total number of macrofauna. The relative abundance of the majority of orders and families did not significantly vary in response to different levels of tree crown density. The influence of herbaceous layer cover on macrofauna was in general less than that of tree crown density. The abundance of litter macrofauna in deciduous forests reached its maximum at sites with the two extreme variants of herbaceous layer cover: sparse herbaceous cover (up to 15%) and dense herbaceous cover (over 90%). The minimal abundance of litter macrofauna was observed at sites with average herbaceous layer density (45–59%). The number of species and the Shannon and Pielou diversity indexes did not vary significantly in relation to changes in herbaceous layer density in deciduous forests of the steppe zone of Ukraine. The number of phtyophage species was higher at sites with average values for herbaceous layer density, while the number of saprophage, zoophage and polyphage species did not significantly change. The dominance structure of litter macrofauna was maximally transformed at sites with the extreme variants of herbaceous layer cover: sparse herbaceous cover (up to 15%) and dense herbaceous cover (over 90%). The median number of ground beetle species reached its maximum at sites with 15–29% herbaceous layer cover. The median of the relative abundance of ground beetles did not significantly change relative to the extent of herbaceous layer cover. The median of the relative abundance of Formicidae reached its maximum at sites with 60–74% herbaceous layer cover and for Isopoda this maximum was reached at sites with 15–59% herbaceous layer cover.
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