In:
Geoscientific Model Development, Copernicus GmbH, Vol. 15, No. 13 ( 2022-07-07), p. 5241-5269
Abstract:
Abstract. 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.
Type of Medium:
Online Resource
ISSN:
1991-9603
DOI:
10.5194/gmd-15-5241-2022
DOI:
10.5194/gmd-15-5241-2022-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2022
detail.hit.zdb_id:
2456725-5
