Pan-Tropical Calibration of Demographic Rates and Forest Structure in E3SM Land Model-FATES

Authors

Jessica F. Needham¹* ([email protected]), Charles D. Koven¹, Rosie Fisher², Ryan Knox¹, Gregory Lemieux¹, Jennifer Holm¹, Jeffrey Chambers¹

Institutions

¹Lawrence Berkeley National Laboratory, Berkeley, CA; ²CICERO Center for International Climate Research, Oslo, Norway

URLs

• https://ngee-tropics.lbl.gov/

Abstract

Observations from forest plots show important differences in aboveground woody productivity, biomass, and turnover of forests across continents, and how these dynamics are changing through time. These patterns are not well captured by the current generation of Earth system models. Researchers compared global simulations of the vegetation demographic model E3SM Land Model-FATES (ELM-FATES) to ground observations of aboveground biomass and carbon turnover from Galbraith et al. (2013), and size-dependent aboveground woody productivity (AWP) and mortality from Piponiot et al. (2022). ELM-FATES with its current default parameters has a high AWP bias across much of the tropics, despite reasonable gross primary production, suggesting potential biases in the plant respiration scheme. The default respiration scheme based on Ryan (1991) was compared with a respiration scheme based on Atkin et al. (2017) to assess parameter sensitivity related to maintenance respiration. Increasing maintenance respiration or using the Atkin respiration scheme both reduced AWP to be more in line with observations. Ensuring that productivity and mortality match observations is essential to correctly modelling carbon exchange between land and atmosphere.