Abstract: In this paper, the Biolog-ECO plates (Biolog, USA) were used to study the functional diversity of edaphon communities in Medicago sativa fields of different growth years in a semiarid loess hilly region. The results are as follows: (1) In the 0-15 cm soil layer, the average absorbance value in vigorous Medicago sativa fields was significantly higher than that in the severely degenerated Medicago sativa fields, degenerated Medicago sativa fields and slope farmland, especially the slope farmland; in the 15-30 cm soil layer, the average absorbance value of severely degenerated Medicago sativa fields was the highest, and it was the lowest in degenerated Medicago sativa fields; (2) In the 0-15 cm soil layer, the Shannon-Wiener index, Pielou index, Simpson index and richness index of Medicago sativa fields were holistically higher than those of slope farmland. In the 15-30 cm soil layer, the diversity index of edaphon of slope farmland was similar to that of severely degenerated Medicago sativa fields but higher than that of degenerated Medicago sativa fields and vigorous Medicago sativa fields, and that of degenerate Medicago sativa fields was the lowest; (3) Principal component analysis (PCA) of functional diversity of edaphon reveals that the functional diversity of edaphon in soil layers of 0-15 cm and 15-30 cm of slope farmland was similar to that of degenerated Medicago sativa fields. The use status of different carbon sources of Medicago sativa fields of different growth years was different; (4) Diversity of edaphon was holistically in an order of vigorous Medicago sativa fields > severely degenerated Medicago sativa fields > slope farmland > degenerated Medicago sativa fields.

Key words: edaphon, diversity index, Biolog-ECO, Medicago sativa, slope farmland, ecological regeneration, loess hilly region