Long-term non-trophic effects of large herbivores on plant diversity are underestimated

QINGQING, C.; BAKKER, J.P.; ALBERTI, J.; BAKKER, E. S.; SMIT, C.; OLFF, H.

Congreso; Netherlands Annual Ecology Meeting; 2019

It is generally assumed that large herbivores promote local biodiversity via removing aboveground biomass and thus reducing competition for light or reducing dominance. However, these results are mainly derived from short-term experiments across different grassland ecosystems. Here we use a unique 46-year cattle grazing and mowing experiment to test whether the effect of grazing on biodiversity is entirely attributed to removal of aboveground biomass. We compared the changes in plant diversity, community composition and dominance structure, between grazing and mowing, as mowing is similar in removing aboveground biomass by grazing, but without having the additional mechanisms. Over time, grazing significantly increased plant diversity compared with mowing. In addition, in contrast with grazing, mowing induced accumulative change in community composition and promoted new dominant species 20 years after the start of the experiment. Our long-term experiment demonstrates that the effect of herbivores on biodiversity cannot solely be attributed to the removal of aboveground biomass, other mechanisms (e.g. urine and dung deposition, and trampling) may be as crucial for upholding biodiversity in grasslands, especially in the long term.