It was expected that there would be a relationship between plant density and arrangement within soybean plantations and ground beetles due to changes of abiotic habitat conditions. The aim of this study was to determinate the effect of different plant arrangements of soybean plants on the abundance and species diversity of ground beetles (Coleoptera, Carabidae). The studies were conducted from 2015 to 2017 at the Experimental Research Station, Wrocław, Poland. The occurrence of beetles was examined on soybeans, growing in four different treatments: row spacing of 15 cm or 30 cm, and seeding density of 50 or 90 seeds per m2. The experiment was conducted in a split-plot design in four replicates. Ground beetles were collected with 16 pitfall traps, with one trap in the middle part of each plot. The obtained results show that the general number of ground beetles was similar between the treatments. Some minor effects were found in species number, which was higher in the lower row spacing treatment. Only less abundant species were significantly affected. The most abundant species in all years and treatments were Pseudoophonus rufipes, Harpalus affinis, Calathus fuscipes and Pterostichus melanarius. The abundance of the above-listed common ground beetle species did not differ significantly between treatments.

Along the paper the new method called Invertebrate Bankfull Assessment method (IBA method) of determination of bankfull discharge is presented. The investigation of bankfull discharge using IBA were performed within one Polish Carpathian stream in the mountain region: the Ochotnica Stream. As an index of bankfull the existence of certain species of invertebrates was used which are present and resistant to specific water discharge conditions. The borders within a cross section of the mountain stream with a gravel bed were defined where characteristic invertebrates are present which are recognized as bankfull borders. Finally three invertebrates benches (IB-ms) were recognized which are characterized by very specific invertebrate species. Bankfull discharge was calculated up to this IB-ms and corelated using Canonical Correspondence Analysis with other values of bankfull calculated for a cross section using different bankfull.