Soil gas flux measurements of grapevines under elevated CO₂ concentration in the VineyardFACE

Abstract

Rising temperatures and increasing CO₂ concentrations in the atmosphere due to climate change cause changes in the behaviour of perennial plants, such as grapevines, which are known to be climate sensitive. Since the Industrial Revolution, the CO₂ concentration has risen from 280 ppm to 430 ppm by 2025. Other greenhouse gases are increasing too, e.g. methane by 170% (from 770 ppb to 1,940 ppb). The FACE (Free Air Carbon Dioxide Enrichment) facility in Geisenheim was established in 2014. Two different cultivars (Vitis vinifera L. cvs. Riesling grafted on SO4, Cabernet Sauvignon grafted on 161-49) were planted in a 12 m diameter ring system. To identify the impact of elevated CO₂ in the atmosphere on grapevines, two treatments were conducted: ambient conditions (aCO₂) display the recent CO₂ concentration (420 ppm in 2025), while the grapevines under elevated CO₂ (eCO₂) achieve +20% to aCO₂ in order to depict the situation in 2050, as outlined in the 2013 IPCC report. Soil contains the most important carbon pool in terrestrial ecosystems (Stockmann et al. 2013).

According to Wohlfahrt et al. 2018 grapevines under eCO₂ achieved a higher biomass such as bunch weight, pruning weight and also leaf biomass for both varieties. Furthermore Rosado-Porto et al. 2023 found significantly different microbial soil respiration within the cover crop under eCO₂. The active soil bacterial diversity in the cover crop row changed but the bare soil samples showed no effect (Rosado-Porto et al. 2023).

In a long-term study at the Geisenheim university soil respiration and methane fluxes were measured for four years in irregular time intervals. Within each CO₂ and ambient plot four measuring rings were installed for each variety underneath the vines. Li-Cor Li-8100 and 7810 were used to measure CO₂ and methane fluxes in the chamber, respectively. The CO₂ flux showed over the years a seasonal pattern where the flux is increasing during the vegetation period for both cultivars. There is a tendency to higher CO₂ fluxes under aCO₂ of Riesling grapes. Cabernet Sauvignon grapevines responding similar both under eCO₂ and aCO₂ concentration. The methane flux is negative over the complete course of investigation. There is a trend to higher methane fluxes under aCO₂ for Cabernet Sauvignon vines in 2023 and 2024 whereas under Riesling, no differences were observed. Even no treatment effect between eCO₂ and aCO₂ was found, negative methane fluxes indicate that vineyard soils can be a sink for atmospheric methane.

References

Rosado‑Porto, S. Ratering, Y. Wohlfahrt, B. Schneider, A. Glatt and S. Schnell (2023). Elevated atmospheric CO2 concentrations caused a shift of the metabolically active microbiome in vineyard soil. BMC Microbiology 23:46, https://doi.org/10.1186/s12866-023-02781-5.

Stockmann, M. A. Adams, J. W. Crawford, D. J. Field, N. Henakaarchchi, M. Jenkins, B. Minasny, A. B. McBratney, V. de Remy de Courcelles, K. Singh, I. Wheeler, L. Abbott, D. A. Angers, J. Baldock, M. Bird, P. C. Brookes, C. Chenu, J. D. Jastrow, R. Lal, J. Lehmann, M. Zimmermann (2013). The knowns, known unknowns and unknowns of sequestration of soil organic carbon. Agriculture, Ecosystems & Environment 164, 80-99.

Wohlfahrt, J.P. Smith, S. Tittmann, B. Honermeier, M. Stoll (2018). Primary productivity and physiological responses of Vitis vinifera L. cvs. under Free Air Carbon dioxide Enrichment (FACE). European Journal of Agronomy 101, 149–162.