Soil biodiversity and soil community composition determine ecosystem multifunctionality

Biodiversity loss has become a global concern as evidence accumulates
that it will negatively affect ecosystem services on which
society depends. So far, most studies have focused on the ecological
consequences of above-ground biodiversity loss; yet a large part of
Earth’s biodiversity is literally hidden below ground. Whether reductions
of biodiversity in soil communities below ground have consequences
for the overall performance of an ecosystem remains
unresolved. It is important to investigate this in view of recent
observations that soil biodiversity is declining and that soil communities
are changing upon land use intensification. We established
soil communities differing in composition and diversity
and tested their impact on eight ecosystem functions in model
grassland communities. We show that soil biodiversity loss and
simplification of soil community composition impair multiple ecosystem
functions, including plant diversity, decomposition, nutrient
retention, and nutrient cycling. The average response of all
measured ecosystem functions (ecosystem multifunctionality)
exhibited a strong positive linear relationship to indicators of soil
biodiversity, suggesting that soil community composition is a key
factor in regulating ecosystem functioning. Our results indicate
that changes in soil communities and the loss of soil biodiversity
threaten ecosystem multifunctionality and sustainability.