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Biogeosciences An interactive open-access journal of the European Geosciences Union
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© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 28 Nov 2019

Submitted as: research article | 28 Nov 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

The Impact of a Simple Representation of Non-Structural Carbohydrates on the Simulated Response of Tropical Forests to Drought

Simon Jones1, Lucy Rowland2, Peter Cox1, Debbie Hemming3, Andy Wiltshire3, Karina Williams3,4, Nicolas C. Parazoo5, Junjie Liu5, Antonio C. L. da Costa6, Patrick Meir7,8, Maurizio Mencuccini9,10, and Anna Harper1 Simon Jones et al.
  • 1College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, Devon EX4 4QF, UK
  • 2College of Life and Environmental Sciences, University of Exeter, Exeter, Devon EX4 4QF, UK
  • 3Met Office Hadley Centre, FitzRoy Road, Exeter EX1 3PB, UK
  • 4Global Systems Institute, University of Exeter, Laver Building, North ParkRoad, Exeter EX4 4QE, UK
  • 5California Institute of Technology, Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA
  • 6Instituto de Geosciencias, Universidade Federal do Para, Belem, Brazil
  • 7Research School of Biology, Australian National University, Canberra ACT 2601, Australia
  • 8School of Geosciences, University of Edinburgh, Edinburgh EH9 3FF, UK
  • 9ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
  • 10CREAF, Universidad Autonoma de Barcelona, Cerdanyola del Valles 08193, Barcelona, Spain

Abstract. Accurately representing the response of ecosystems to environmental change in land surface models (LSM) is crucial to making accurate predictions of future climate. Many LSMs do not correctly capture plant respiration and growth fluxes, particularly in response to extreme climatic events. This is in part due to the unrealistic assumption that total plant carbon expenditure (PCE) is always equal to gross carbon accumulation by photosynthesis. We present and evaluate a simple model of labile carbon storage and utilisation (SUGAR), designed to be integrated into an LSM, that allows simulated plant respiration and growth to vary independently of photosynthesis. SUGAR buffers simulated PCE against seasonal variation in photosynthesis, producing more constant (less variable) predictions of plant growth and respiration relative to an LSM that does not represent labile carbon storage. This allows the model to more accurately capture observed carbon fluxes at a large-scale drought experiment in a tropical moist forest in the Amazon, relative to the Joint UK Land Environment Simulator LSM (JULES). SUGAR is designed to improve the representation of carbon storage in LSMs and provides a simple framework that allows new processes to be integrated as the empirical understanding of carbon storage in plants improves. The study highlights the need for future research into carbon storage and allocation in plants, particularly in response to extreme climate events such as drought.

Simon Jones et al.
Interactive discussion
Status: open (extended)
Status: open (extended)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Simon Jones et al.
Data sets

JULES output dataset S. Jones, A. Harper, and K. Williams

Model code and software

SUGAR example code S. Jones

Simon Jones et al.
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Short summary
Non-structural carbohydrates (NSC) are an important set of molecules that help plants to grow and respire when photosynthesis is restricted by extreme climate events. In this paper we present a simple model of NSC storage and assess the effect that it has on simulations of vegetation at the ecosystem scale. Our model has the potential to significantly change predictions of plant behaviour in global vegetation models which would have large implications for predictions of the future climate.
Non-structural carbohydrates (NSC) are an important set of molecules that help plants to grow...