Abstract
Over the past several decades, the land modeling community has recognized the importance of nutrient regulation on the global terrestrial carbon cycle. Implementations of nutrient limitation in land models are diverse, varying from applying simple empirical down-regulation of potential gross primary productivity under nutrient deficit conditions to more mechanistic treatments. In this study, we introduce a new approach to model multinutrient (nitrogen [N] and phosphorus [P]) limitations in the Energy Exascale Earth System Model (E3SM) Land Model version 1 (ELMv1-ECA). The development is grounded on (1) advances in representing multiple-consumer, multiple-nutrient competition; (2) a generic dynamic allocation scheme based on water, N, P, and light availability; (3) flexible plant CNP stoichiometry; (4) prognostic treatment of N and P constraints on several carbon cycle processes; and (5) global data sets of plant physiological traits. Through benchmarking the model against best knowledge of global plant and soil carbon pools and fluxes, we show that our implementation of nutrient constraints on the present-day carbon cycle is robust at the global scale. Compared with predecessor versions, ELMv1-ECA better predicts global-scale gross primary productivity, ecosystem respiration, leaf area index, vegetation biomass, soil carbon stocks, evapotranspiration, N2O emissions, and NO3 - leaching. Factorial experiments indicate that representing the phosphorus cycle improves modeled carbon fluxes, while considering dynamic allocation improves modeled carbon stock density. We also highlight the value of using the International Land Model Benchmarking (ILAMB) package to evaluate and document performance during model development.
| Original language | English |
|---|---|
| Pages (from-to) | 2238-2258 |
| Number of pages | 21 |
| Journal | Journal of Advances in Modeling Earth Systems |
| Volume | 11 |
| Issue number | 7 |
| DOIs | |
| State | Published - 2019 |
Funding
This research was supported by Energy Exascale Earth System Modeling (E3SM, https://e3sm.org/) Project and the Reducing Uncertainties in Biogeochemical Interactions through Synthesis and Computation (RUBISCO) Scientific Focus Area, which are sponsored by the Earth and Environmental Systems Modeling (EESM) Program under the Office of Biological and Environmental Research of the U.S. Department of Energy Office of Science. Lawrence Berkeley National Laboratory (LBNL) is managed by the University of California for the U.S. Department of Energy under contract DE-AC02-05CH11231. Oak Ridge National Laboratory (ORNL) is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. All data are available at figshare data repository: https://figshare.com/articles/ilamb-ELMECA-data_zip/5722369. The E3SM model code is available at https://e3sm.org/.
| Funders | Funder number |
|---|---|
| EESM | |
| Earth and Environmental Systems Modeling | |
| Energy Exascale Earth System Modeling | |
| Office of Biological and Environmental Research | |
| U.S. Department of Energy Office of Science | |
| U.S. Department of Energy | DE-AC02-05CH11231 |
| University of California | |
| Oak Ridge National Laboratory | DE-AC05-00OR22725 |