Representation of the phosphorus cycle in the Joint UK Land Environment Simulator (vn5.5_JULES-CNP)

Nakhavali, Mahdi André; Mercado, Lina M. ORCID: https://orcid.org/0000-0003-4069-0838; Hartley, Iain P.; Sitch, Stephen; Cunha, Fernanda V.; di Ponzio, Raffaello; Lugli, Laynara F.; Quesada, Carlos A; Andersen, Kelly M.; Chadburn, Sarah E.; Wiltshire, Andy J.; Clark, Douglas B. ORCID: https://orcid.org/0000-0003-1348-7922; Ribeiro, Gyovanni; Siebert, Lara; Moraes, Anna C.M.; Schmeisk Rosa, Jéssica; Assis, Rafael; Camargo, José L.. 2022 Representation of the phosphorus cycle in the Joint UK Land Environment Simulator (vn5.5_JULES-CNP). Geoscientific Model Development, 15 (13). 5241-5269. 10.5194/gmd-15-5241-2022

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Abstract/Summary

Most land surface models (LSMs), i.e. the land components of Earth system models (ESMs), include representation of nitrogen (N) limitation on ecosystem productivity. However, only a few of these models have incorporated phosphorus (P) cycling. In tropical ecosystems, this is likely to be important as N tends to be abundant, whereas the availability of rock-derived elements, such as P, can be very low. Thus, without a representation of P cycling, tropical forest response in areas such as Amazonia to rising atmospheric CO2 conditions remain highly uncertain. In this study, we introduced P dynamics and its interactions with the N and carbon (C) cycles into the Joint UK Land Environment Simulator (JULES). The new model (JULES-CNP) includes the representation of P stocks in vegetation and soil pools, as well as key processes controlling fluxes between these pools. We develop and evaluate JULES-CNP using in situ data collected at a low-fertility site in the central Amazon, with a soil P content representative of 60 % of soils across the Amazon basin, to parameterize, calibrate, and evaluate JULES-CNP. Novel soil and plant P pool observations are used for parameterization and calibration, and the model is evaluated against C fluxes and stocks and those soil P pools not used for parameterization or calibration. We then evaluate the model at additional P-limited test sites across the Amazon and in Panama and Hawaii, showing a significant improvement over the C- and CN-only versions of the model. The model is then applied under elevated CO2 (600 ppm) at our study site in the central Amazon to quantify the impact of P limitation on CO2 fertilization. We compare our results against the current state-of-the-art CNP models using the same methodology that was used in the AmazonFACE model intercomparison study. The model is able to reproduce the observed plant and soil P pools and fluxes used for evaluation under ambient CO2. We estimate P to limit net primary productivity (NPP) by 24 % under current CO2 and by 46 % under elevated CO2. Under elevated CO2, biomass in simulations accounting for CNP increase by 10 % relative to contemporary CO2 conditions, although it is 5 % lower compared to CN- and C-only simulations. Our results highlight the potential for high P limitation and therefore lower CO2 fertilization capacity in the Amazon rainforest with low-fertility soils.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.5194/gmd-15-5241-2022
UKCEH and CEH Sections/Science Areas:	Hydro-climate Risks (Science Area 2017-)
ISSN:	1991-959X
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - full text available via Official URL link.
NORA Subject Terms:	Meteorology and Climatology
Date made live:	09 Dec 2021 09:17 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/531525

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