Soil nematode communities of coniferous and deciduous forests in protected areas of the Republic of Karelia were studied with regard to their latitudinal position. A series of parameters (taxonomic diversity, nematode population density, eco-trophic structure and ecological indices of soil food web) were used to assess the nematode communities. The highest nematode taxonomic diversity was observed in linden forests and the lowest one in soils of pine forests. Bacterial-, fungal feeders and nematodes associated with plants dominated the soil nematode community structure in all types of forest biocoenoses. According to ecological indices of the food web (SI, EI), the soil ecosystems were assessed as undisturbed, with complex trophic linkages and a moderate level of soil organic enrichment. One exception was northern taiga forests in Kostomukshsky Strict Nature Reserve, where low SI values indicated an impact of detrimental environmental factors on the soil ecosystems. It was found that the main distinction of northern deciduous forests from southerner ones is the diversity and relative abundance of plant parasitic nematodes. It was for the first time demonstrated here that the graphic triangle constructed from ecological indices of the food web can be effectively applied to identify the features of soil nematode communities specific to forest type and local habitat conditions.