Effects of elevated CO2 on plant C-N-P stoichiometry in terrestrial ecosystems: A meta-analysis

Abstract

A substantial number of experiments have so far been carried out to study the response of the C-N-P stoichiometry of terrestrial plants to the rising CO₂ level of the earth. However, there is a need of systematic evaluation for assessing the impact of the elevated CO₂ on plant C-N-P stoichiometry. In the present investigation, a comprehensive meta-analysis involving 386 published reports and including 4481 observations has been carried out. The goal of the research was to determine the response of plants to their C-N-P stoichiometry due to elevated levels of global atmospheric CO₂. The results showed that rising CO₂ altered the concentration of C (+2.19%, P < 0.05), N (-9.73%, P < 0.001) and P (-3.23%, P < 0.001) and C:N (+13.29%, P < 0.001) and N:P ratios (-7.32%, P < 0.0001). Overall, a slightly increasing trend in the C:P ratio (P > 0.05) in the plant was observed. However, plant leaf, shoot and herbaceous type of plants showed more sensitivity to rising CO₂. CO₂ magnitude exhibited a positive effect (P < 0.05) on C:N ratio. Additionally, "CO₂ acclimation" hypothesis as proposed by the authors of the current paper was also tested in the study. Results obtained, especially, show changes of C and N concentrations and C:P ratio to an obvious down-regulation for long-term CO₂ fumigation. At spatial scales, a reduction of plant N concentration was found to be higher in the southern hemisphere. The CO₂ enrichment methods affected the plant C-N-P stoichiometry. Compared to FACE (free-air CO₂ enrichment), OTC (open top chamber) showed larger changes of C, N, P, and N:P. The results of the present study should, therefore, become helpful to offer a better understanding towards the response of the terrestrial plant C-N-P stoichiometry to an elevated global atmospheric CO₂ in the future.

Keywords: CO(2) acclimation; Experiment condition; Meta-analysis; Plant stoichiometry; Rising CO(2); Spatial difference.