EGU21-11142
https://doi.org/10.5194/egusphere-egu21-11142
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Eco-evolutionary responses of plant communities to drought and rainfall variability

Jaideep Joshi1, Benjamin Stocker2,3, Florian Hofhansl1, Shuangxi Zhou4,5,6, Åke Brännström7, Iain Colin Prentice4,8,9, and Ulf Dieckmann1,10
Jaideep Joshi et al.
  • 1Advancing Systems Analysis Program, International Institute for Applied Systems Analysis, 2361 Laxenburg, Austria (joshi@iiasa.ac.at)
  • 2Department of Environmental Systems Science, ETH, Universitätsstrasse 2, 8092 Zürich, Switzerland
  • 3Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland
  • 4Department of Biological Sciences, Macquarie University, NSW 2109, Australia
  • 5CSIRO Agriculture and Food, Glen Osmond, SA, Australia
  • 6The New Zealand Institute for Plant and Food Research Limited, Hawke’s Bay, New Zealand
  • 7Department of Mathematics and Mathematical Statistics, Umeå University, 90187 Umeå, Sweden
  • 8Imperial College London, Department of Life Sciences, Silwood Park Campus, Ascot SL5 7PY, UK
  • 9Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084, China
  • 10Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies (Sokendai), Hayama, Kanagawa 240-0193, Japan

The future Earth is projected to experience elevated rainfall variability, with more frequent and intense droughts, as well as high-rainfall events. Increasing CO2 concentrations are expected to raise terrestrial gross primary productivity (GPP), whereas water stress is expected to lower GPP. Plant responses to water stress vary strongly with timescale, and plants adapted to different environmental conditions differ in their functional responses. Here, we embed a unified optimality-based theory of stomatal conductance and biochemical acclimation of leaves we have recently developed [Joshi, J. et al. (2020) Towards a unified theory of plant photosynthesis and hydraulics. bioRxiv 2020.12.17.423132] in an eco-evolutionary vegetation-modelling framework, with the goal to investigate emergent functional diversity and associated GPP impacts under different rainfall regimes.

The model of photosynthesis used here simultaneously predicts the stomatal responses and biochemical acclimation of leaves to atmospheric and soil-moisture conditions. Using three hydraulic traits and two cost parameters, it successfully predicts the simultaneous declines in CO2 assimilation rate, stomatal conductance, and leaf photosynthetic capacity caused by drying soil. It also correctly predicts the responses of CO2 assimilation rate, stomatal conductance, leaf water potential, and leaf photosynthetic capacity to vapour pressure deficit, temperature, ambient CO2, light intensity, and elevation. Our model therefore captures the synergistic effects of atmospheric and soil drought, as well as of atmospheric CO2 changes, on plant photosynthesis and transpiration.

We embed this model of photosynthesis and transpiration in a trait-height-patch structured eco-evolutionary vegetation model. This model accounts for allometric carbon allocation, height-structured competition for light, patch-structured successional dynamics, and coevolution of plant functional traits. It predicts functional species mixtures and emergent ecosystem properties under different environmental conditions. Using this model, we investigate the evolution of plant hydraulic strategies under different regimes of drought and rainfall variability. Our approach provides an eco-evolutionarily consistent framework to scale up the responses of plant communities from individual plants to ecosystems to provide ecosystem-level predictions of functional diversity, primary production, and plant water use, and could thus be used for reliable projections of the global carbon and water cycles under future climate scenarios.

How to cite: Joshi, J., Stocker, B., Hofhansl, F., Zhou, S., Brännström, Å., Prentice, I. C., and Dieckmann, U.: Eco-evolutionary responses of plant communities to drought and rainfall variability, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11142, https://doi.org/10.5194/egusphere-egu21-11142, 2021.

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