Zhukova Y. Ecomorphic organization of floodplain soils macrofauna within the natural reserve "Dniprovs'ko-Orils'kyi"

The dissertation reviles the dependence between the ecomorphic organization of soil macrofauna groups of floodplain ecosystems on soil conditions and vegetation cover and assessed the morphological diversity of the soils. The studies were conducted in Dnipro River floodplain of "Dnipro-Orilskiy" Nature Reserve region. The studies allowed to identify features of the ecological regimes of floodplain ecosystems based on phytoindication, compare ecological regimes of short- and long-term floodplain ecosystems and assess the quantity of alpha-, beta-, and gamma-diversity of the metagrouping of soil macrofauna. As a result features of the ectomorphic structure of groups of soil macrofauna were indifined. The ecomorphic structure served as base for functional groups of soil macrofauna definition and evaluation of the mechanisms of functional stability of the ecomorphic structure of soil macrofauna groups. The studies showed that the investigated loodplain soils were represented by Gleysol and Fluvisol. That has been described by a diverse combination of soil properties, creating the basis for a volumetric coverage of possible ecological regimes of the existence of soil animals in floodplain ecosystems. Identified that there were 109 vascular plant species in the surveyed floodplain ecosystems. Plant groups were characterized by common features of ecological regimes that may be assessed by phytoindicative procedures. The regime of hydration variability was favorable for hydrocontrastophobes, the soil acidity regime - for subacidophiles, for saline regime - semi oligotrophic, the carbonate regime - for acarbonatophiles, the light regime is typical of light forests. It has been shown that short-flood ecosystems differed by lower parameters of the mode of hydration variability, lower level of moisture, higher content of carbonates in the soil, and lower level of aeration. Ecosystems under the conditions of a longterm flood regime also differed in the variability of the moisture regime, the level of carbonate content, and the moisture regime and the content of nitrogen compounds. The gamma-diversity of the macrofauna metagroup of floodplain soils was 75 species, the alpha-diversity of the group was 8.76 species, the beta-diversity was 8.58. Amphicenoticity had a different ratio of forest and meadow components that features the animal population of floodplain soils. Mesophiles dominated in the hygromorphic structure. But the hygromorphic structure could be rebuilt with a preference for either xerophilic or hygrophilic hygromorphs, depending on specific conditions. The group trophocoenomorphic structure was mesotrophic with a significant presence of both oligo- and megatrophocenomorphs, that indicates significant variability in the conditions of mineral nutrition of floodplain ecosystems. Inhabitants of floodplain ecosystems are demanding to the conditions of soil respiration. Aeromorphs were represented by aero- and subaerophiles. Epigean forms dominated in the topomorphic structure. It has been proved that the peculiarities of the ecomorphic structure of soil macrofauna groups at the ecosystem level are the basis for establishing the typuloid, elaterid-scaraboid (and its caraboid derivative), diplopoid and lumbricoid functional groups. The intra-ecosystem differentiation of soil macrofauna grouping was caused by the heterogeneity of ecological regimes, as a consequence of the variety of soil conditions, vegetation cover, and relief. The grouping of soil macrofauna of a specific ecosystem consisted of two to four functional groups. The leading functional group corresponded to the nominative complex. The existence of complex has been found by inter-ecosystem differentiation. Minor functional groups were derivatives of other complexes, presented in this ecosystem is secondary. Ecomorphic differentiation was a mechanism of functional stability of soil macrofauna communities in changing conditions of floodplain soils.