Dynamics of nematode assemblages and soil function in adjacent restored and degraded soils following disturbance

Responses of nematode assemblages and soil function (short-term decomposition) in restored and degraded soil following an experimental disturbance (copper, chloroform, heat or drying) were monitored for 65 days. We tested the hypotheses: restoration enhanced the measured soil parameters; stability to disturbance was higher in degraded soil due to induced tolerance; and whether changes of the nematode assemblage were related to soil function. Even after disturbance, greater nematode abundance (>150 vs >10 per 100 g soil), nematode richness (D′ > 1.0 vs >0.4) and function (>1.0 vs >0.05 mg CO2 g−1 week−1) were maintained in restored than in degraded soil, respectively. An increase in nematode enrichment index (from 60 to >75) following all disturbances was attributed to the relatively high abundance of tolerant fungivores. The greater stability of the nematode structure index in degraded soil following heat and drying (120% and 125% respectively of the control), than in restored soil (90% and 30% of control) was due to a higher proportion of tolerant omnivores and carnivores. Thus some higher trophic level nematodes, with high c–p values, were tolerant to disturbance. However, stability of function was greater for restored than degraded soil, with a reduction over time in the degraded soil regardless of disturbance type. The differences in the responses of nematodes and soil function to disturbance suggest that nematodes could provide complementary insights into soil stability.

► Higher nematode abundance, diversity and function was in restored than degraded soil. ► Stability of nematodes or soil function relied on disturbance type soil experienced. ► Nematodes and soil function was more stable to heat and drying in degraded soil. ► Parameters of nematode differed from soil function in their response to disturbance. ► Nematode assemblage analysis is a complementary measure to indicate soil stability.