Separating the effects of temperature and carbon allocation on the diel pattern of soil respiration in the different phenological stages in dry grasslands

PLoS One. 2019 Oct 17;14(10):e0223247. doi: 10.1371/journal.pone.0223247. eCollection 2019.

Abstract

Diel variability of soil respiration is influenced by several factors including temperature and carbon allocation as the most significant ones, co-varying on multiple time scales. In an attempt to disentangle their effects we analyzed the dynamics of soil respiration components using data from a three-year soil respiration study. We measured CO2 efflux in intact, root-excluded and root- and mycorrhizal fungi excluded plots and analyzed the diel variability in different phenological stages. We used sine wave models to describe the diel pattern of soil respiration and to disentangle the effects of temperature from belowground carbon allocation based on the differences between component dynamics inferred from the fitted models. Rhizospheric respiration peaked 8-12 hours after GPP peak, while mycorrhizal fungi respiration had a longer time lag of 13-20 hours. Results of δ13CO2 isotopic signals from the respiration components showed similar patterns. It was found that drought affected the component respiration rates differently. Also, the speed and the amount of carbon allocation to the roots as well as to the mycorrhizal fungi was reduced under drought. We conclude that the diel variability of soil respiration is the result of the integrated patterns of temperature- and carbon allocation-driven components in dry grasslands and their share depends on their phenological stages and stress state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon / metabolism
  • Carbon Dioxide / metabolism*
  • Carbon Isotopes / chemistry
  • Cell Respiration / physiology
  • Droughts
  • Grassland*
  • Photosynthesis / physiology*
  • Plant Roots / physiology*
  • Respiration
  • Soil / chemistry
  • Temperature

Substances

  • Carbon Isotopes
  • Soil
  • Carbon Dioxide
  • Carbon

Grants and funding

This research was supported by the Higher Education Institutional Excellence Program (TUDFO/47138/2019-ITM) awarded by the Ministry of Innovation and Technology of Hungary within the framework of water related researches of Szent István University. Soil respiration measurements were also supported by OTKA-PD 100575 project. Szilvia Fóti and Krisztina Pintér acknowledge the support of GINOP-2.2.1-15-2017-00061 project. János Balogh acknowledges the support of 2017-1.3.1-VKE-2017-00030 project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.