Decoupled responses of above- and below-ground stability of productivity to nitrogen addition at the local and larger spatial scale

Temporal stability of net primary productivity (NPP) is important for predicting the reliable provisioning of ecosystem services under global changes. Although nitrogen (N) addition is known to affect the temporal stability of aboveground net primary productivity (ANPP), it is unclear how it impacts that of belowground net primary productivity (BNPP) and NPP, and whether such effects are scale dependent. Here, using experimental N addition in a grassland, we found different responses of ANPP and BNPP stability to N addition at the local scale and that these responses propagated to the larger spatial scale. That is, N addition significantly decreased the stability of ANPP but did not affect the stability of BNPP and NPP at the two scales investigated. Additionally, spatial asynchrony of both ANPP and BNPP among communities provided greater stability at the larger scale and was not affected by N addition. Our findings challenge the traditional view that N addition would reduce ecosystem stability based on results from aboveground dynamics, thus highlighting the importance of viewing ecosystem stability from a whole system perspective.

Automated summary

This study investigates the impact of nitrogen addition on the temporal stability of aboveground and belowground net primary productivity (ANPP and BNPP) in a grassland ecosystem. The results show that nitrogen addition decreases the stability of ANPP, but does not affect the stability of BNPP and NPP at the investigated scales. Additionally, spatial asynchrony of ANPP and BNPP among communities provides greater stability at a larger scale and is not affected by nitrogen addition.