SPATIAL DISTRIBUTION OF SOIL NEMATODES IN RHIZOSPHERE OF POPLAR AND BIRCH
The following paper reflects the study of the number and generic composition of soil nematodes in poplar and birch root zones. The authors analyzed spatial distribution of soil nematode communities near in root zones of birches and poplars growing in forest areas near the city of Tomsk and located at a distance of 20, 40, 60 and 80 cm from the root collar. The researchers isolated nematodes applying the modified Berman technique to take 15-30 g of each soil sample three times and used triethanolamine + formalin + water in the ratio 2:7:91 as a fixative substance. The population density of nematodes was calculated per 100 g of soil. The studies revealed 11 nematode genera belonging to the 4 trophic groups in birch root zones and 9 nematode genera belonging to 5 trophic groups in poplar root zone. Plant parasites are the dominant group of nematodes. Another trophic group of nematodes is presented by bacteriotrophes. The study revealed an insignificant proportion of predatory nematodes and nematodes associated with plants, along with high levels bacteriotroph nematodes, which is a characteristic phenomenon of nematodes in forest habitats. Poplar root zones contained a group of polytrophic nematodes. Throughout the study, the number of soil nematodes changed due to changes in soil moistening. The maximum number of soil nematodes was registered at a distance of 20 cm from the root collar. The study of root zones showed that Meloidodera is the dominant nematode genera, while Mononchus, Rhabditis, Plectus are subdominant genera.