Nematode numbers, biomass and respiratory metabolism in a beech woodland-Wytham Woods, Oxford

Abstract

The mean annual population density of nematodes in the litter and upper 6 cm of soil was found to be 368,000 m^-2. Mean individual live weight biomass approximated 0.2 μg and mean biomass was calculated to be 74.6 mg live weight m^-2. No evidence of seasonal vertical migration between the litter, 0-3 cm and 3-6 cm strata was found and on average these strata contained 21.9, 46.2 and 31.9% respectively of the total number of nematodes recovered. The equivalent biomass values were 26.14, 56.57, and 17.29%. Total numbers revealed a general picture of low densities in spring and high ones in early winter, whereas biomass m^-2 was low in late summer - autumn and high in winter. The annual oxygen consumption of the extracted nematodes was calculated to approximate 0.211 m^-2 (≈4.0 kJ m^-2) but when corrected for the effect of individual biomass (weight specific oxygen uptake) was equivalent to an energy expenditure ≈6.0 kJ m^-2 which in its turn, because of the efficiencies of extraction, probably accounts for only 87% of the total energy expenditure by the nematode fauna. The nematodes were estimated to be responsible for a minimum of 0.11% to a maximum of 0.13% of the total "soil" respiration. A production/biomass ratio of 5.16 was estimated as was a net population production efficiency of 36.63%.