Nematode Fauna in Spruce Forest Soils: a Qualitative/ Quantitative Comparison

Abstract

Nematode species composition, population density and trophic structure were investigated in 60 to 100 yr old spruce stands. Most of the 106 species observed were found at the least acidified sites with a thick organic layer, fewer species were found at the sites with acidified soils and extremely thin organic layers. Population density varied between 250 and 1900 individuals per g dry weight, or between 1.4 and 5.1 x 10 6 individuals per m 2 , respectively. The numbers decreased with depth. All sites were dominated by bacterial feeders, followed by root and fungal feeders. Obligate plant parasites, omnivores and predators were scarce. Commonly the bacterial feeders with their dominant taxa Plectus, Wilsonema schuurmansstekhoveni, Teratocephalus stratumus and Metateratocephalus crassidens were found in the upper soil horizons. Only Acrobeloides buetschlii and A. nanus preferred deeper soil layers. Root and fungal feeders were mainly species of Filenchus and Aphelenchoides. In general they increased with depth. The Maturity Index at most sites was low, suggesting a dominance of r-strategists among the nematode population. Only at the less acidified sites with an organic layer of 10 cm were higher proportions of Κ-strategists and consequently higher MI values observed.