Effects of water supply on plant stoichiometry of C, N, P in Inner Mongolia grasslands

Aims: Plant stoichiometry is known to influence ecological processes and element cycles in ecosystems, which in turn can all be affected by ongoing climate change. While previous studies mainly focused on warming, drought or species invasion, effects of changing water supply on plant stoichiometry have not been well explored. Methods: To study how water supply affects plant stoichiometry (here C:N, N:P), and whether such effects differ among plant species, a manipulative experiment was conducted in which four grass species (Leymus chinensis, Stipa grandis, Artemisia frigida and Potentilla acaulis) dominant in the Inner Mongolia steppe were subjected to a gradient of water supply via changes in growing-season rainfall. Results: Water supply significantly impacted C:N and N:P, and these effects differed among grass species. Specifically, while C:N of A. frigida and P. acaulis was unaffected by water supply, C:N of L. chinensis and S. grandis increased with increasing precipitation. Furthermore, N:P of A. frigida showed a unimodal pattern along the imposed precipitation gradient. Whereas aboveground and belowground N:P showed similar trends (but different patterns) with changing water supply, this was not the case for aboveground and belowground C:N. As a result, plant stoichiometry between aboveground and belowground parts followed an allometric pattern. Conclusions: Changes in water supply can significantly modulate plant stoichiometry. These results could improve our understanding of the dynamics of grasslands under climate change.