Patterns of relative magnitudes of soil energy channels and their relationships with environmental factors in different ecosystems in Romania

The percentage compositions of soil herbivorous, bacterivorous and fungivorous nematodes in forests, grasslands and scrubs in Romania was analysed. Percentages of nematode abundance, biomass and metabolic footprint methods were used to evaluate the patterns and relative size of herbivory, bacterial- and fungal-mediated channels in organic and mineral soil horizons. Patterns and magnitudes of herbivore, bacterivore and fungivore energy pathways differed for a given ecosystem type and soil depth according to the method used. The relevance of herbivore energy channel increased with soil depth due to higher contribution of root-feeders. Ectoparasites, sedentary parasites and epidermal cell and root hair feeders were the most important contributors to the total biomass and metabolic footprints of herbivores. Metabolic footprint method revealed the general dominance of bacterial-based energy channel in all five types of ecosystems. The influence of altitude and climatic factors on percentages of abundance, biomass and metabolic footprints of herbivores, bacterivores and fungivores decreased with soil depth, whereas the influence of humus content, cation-exchange capacity and base saturation increased. Vegetation, altitude, climate and soil physico-chemical characteristics are important factors that influenced the abundance, biomass and metabolic footprints of herbivores, bacterivores and fungivores.