The relationship between dung beetle species richness and ecosystem functioning

• Diversity of dung beetle species accelerated N and C transfer from the grass-produced dung to the soil.
• Such results were not seen when grain-produced dung was used for experiment.
• The effect of dung diversity on plant productivity was unclear.

Theory suggests that increasing species diversity increases ecosystem functioning, but there have been few attempts to demonstrate this function by manipulating dung beetle assemblages. We experimentally controlled the species richness of dung beetles and the dung type (from grass-fed or grain-fed cattle) in pots; we then compared soil nutrient levels and plant productivity among pots. Diversity of dung beetle species accelerated N and C transfer from the grass-produced dung to the soil, although its effect on plant productivity was unclear. We attributed the effect on nutrient supply to the following possibilities: (1) diversity may promote competition among species, thus stimulating burying activity. (2) Grass-produced dung has been a traditional resource for Japanese dung beetles, which may therefore be better adapted to using it than to using grain-produced dung.