Through the most exhaustive tropical forest carbohydrate sampling and analysis done to date, researchers found that canopy tree carbohydrate concentrations are insensitive to both seasonal drought and long-term climate. They also identified easily measured traits that may be predictive of carbohydrate concentrations.
These findings help to unify our understanding of forest carbohydrate dynamics across the few existing tropical datasets. Since carbohydrates play an important role in forest survival, this may improve our ability to simulate vegetation dynamics in Earth System Models, and trait relationships should simplify model benchmarking.
Non-structural carbohydrates (NSCs), the organic compounds that drive plant metabolism, have rarely been studied in moist tropical forests, so their regulation in these systems is poorly understood. These compounds may modulate tree drought response and can become depleted if demand (i.e., growth, defense, respiration) exceeds supply (i.e., photosynthesis). As a result, Earth System Models (ESMs) rely on carbohydrates as a metric for vegetation survival. Researchers from the NGEE-Tropics project measured foliar and branch NSCs of 23 canopy tree species across a large precipitation gradient in Panama during the 2015-2016 El Nino drought to examine how short- and long-term climatic variation impacts carbohydrate dynamics. There was large variation in NSCs across species, however there was no change in total NSCs as the drought progressed nor across the rainfall gradient. Some NSC variation could be explained by easily and ubiquitously measured traits, providing potential for improved model benchmarking. These findings suggest that NSCs are an allocation priority in moist tropical forests and should improve our ability to capture vegetation dynamics in ESMs.
Contacts (BER PM)
Terrestrial Ecosystem Science
Chonggang Xu, LANL, firstname.lastname@example.org and Nate McDowell, PNNL, email@example.com
This work was supported by the Next-Generation Ecosystem Experiments (NGEE) Tropics project, funded by the US Department of Energy, Office of Biological and Environmental Research.
Dickman, L.T., N.G. McDowell, C. Grossiord, A.D. Collins, B.T. Wolfe, M. Detto, S.J. Wright, J.A. Medina-Vega, D. Goodsman, A. Rogers, S.P. Serbin, J. Wu, K.S. Ely, S.T. Michaletz, C. Xu, L. Kueppers, and J.Q. Chambers. “Homeostatic maintenance of non-structural carbohydrates during the 2015-2016 El Nino drought across a tropical forest precipitation gradient.” Plant, Cell & Environment 42(5),1705-1714 (2018). [DOI: 10.1111/pce.13501]
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