Extreme drought impacts ecosystem function and processes dramatically. However, a comprehensive understanding of how extreme drought affects root biomass at regional scales remains elusive. Here, we investigated the effects across six grasslands with extreme drought treatment replicated across a precipitation gradient in Inner Mongolia, China. We found the root biomass and belowground net primary productivity (BNPP) were significantly positively correlated with precipitation at the reginal scale. Extreme drought decreased the slope of this correlation in 0-10 cm and increased in 10-20 cm. Root biomass and BNPP increased by extreme drought in the four relatively arid sites and decreased in the two relatively mesic sites in 0-10 cm, and the reverse pattern showed in 10-20 cm. These shifts were driven by the response of soil moisture. Our findings suggest that including vertical responses of belowground primary productivity to extreme drought should improve models predictions of plant roots to future climate change.
Plant biochemical reactions are dependent on the combined action of multiple elements. However, it remains unclear how these elements co-vary to adapt to environmental change. Here, we propose a novel concept of the multi-element network (MEN) including the mutual effects between elements to more effectively explore the alterations in response to long-term nitrogen (N) deposition simulations. MENs were constructed with 18 elements and were species specific. Macroelements were more stable, but microelements were more susceptible to N deposition. Interestingly, higher MEN plasticity determined increased relative aboveground biomass (species importance) for different species in one functional group under simulated N deposition. Furthermore, the association between MEN plasticity and species importance was consistently verified along a dry–wet transect. In summary, MENs provide a novel approach for exploring the adaptation strategies of plants and to better predict community composition under altering nutrient availability or environmental stress associated with future global climate change.