Effects of daytime and nighttime warming on C: N: P stoichiometry in leaf-root-soil system and plant biomass

Abstract

Background and aims

Daytime warming (DW) and nighttime warming (NW) affect terrestrial ecosystems differently. Carbon (C): nitrogen (N): phosphorus (P) stoichiometry ratios can reflect plant nutrient dynamics in changing environments. However, it is not clear how C: N: P stoichiometry ratios of different plant organs and soil respond to DW and NW, and consequently responses affect the biomass.

Methods

We investigated how experimental warming (CK: no warming, DW: daytime warming, NW: nighttime warming, DW+NW: daily warming) impact C: N: P stoichiometry in leaf-root-soil system and plant above-and belowground biomass.

Results

The results showed that all warming treatments significantly increased biomass and decreased soil C: N and C: P ratios, but the sum of the net effects of DW and NW treatments was not equal to the effect of DW+NW treatment. There were no significant changes observed in leaf total N content, leaf C: N, root total P content, and root C: P in all warming treatments. Soil variable group explain more of the variation in AGB and root variable group explain more of the variation in BGB. Our findings demonstrated that the effects of DW and NW treatments on soil C: N: P stoichiometry ratios were asymmetric, but on plant C: N: P stoichiometry ratios were similar. The C: N: P stoichiometric ratios of plant roots and leaves in response to daytime and nighttime warming are regulated by N and P, respectively, indicating that N and P have different partitioning strategies in leaves and roots.

Conclusions

Plant biomass responses to warming are tightly linked to C: N: P stoichiometric coordination across the leaf-root-soil system. These results have important implications for our understanding of how plants regulate N and P partitioning in above- and belowground organs under daytime and nighttime warming and highlight the important role of plant N and P asymmetric partitioning strategies in optimizing survival and increasing biomass.