Belowground plant productivity responds similarly as soil microbial productivity rather than aboveground plant productivity to nitrogen deposition in the Eurasian steppe

Abstract

Abstract Purpose It is a central goal in current ecology to investigate the effects of global changes on ecosystem productivity, which includes above- and below-ground plant productivity as well as soil microbial productivity, but most studies focus on aboveground plant productivity. As plant and microbial communities have different attributes, it is intuitive to hypothesize that belowground plant root productivity will respond to global changes more similarly as aboveground stem/leaf productivity than soil microbial productivity; however, this hypothesis remains largely unexplored. Methods Here we conducted a long-term nitrogen deposition experiment in the Eurasian steppe, manipulating nine rates (0–50 g N m− 2 yr− 1) at two frequencies under two management strategies (fencing or mowing). Results Belowground plant productivity was found to respond similarly as soil microbial productivity rather than aboveground plant productivity, contrary to the hypothesis. And this pattern was more obvious under mowing than fencing, because mowing decreased soil water content and caused another pressure beyond the decreased pH induced by N addition. Conclusions Overall, our results demonstrated the importance of microhabitat (below- or above-ground) relative to community attribute (plants or microorganisms) in determining productivity response to nitrogen deposition, emphasizing the necessity to integratively study the response of both above- and below-ground productivities to global changes.

Keywords

• Belowground productivity
• Microbial biomass
• Nitrogen deposition