Towards a more physiological representation of vegetation phosphorus processes in land surface models

Jiang, Mingkai; Caldararu, Silvia; Zaehle, Sönke; Ellsworth, David S.; Medlyn, Belinda E.

doi:10.1111/nph.15688

Cited by 72 publications

(74 citation statements)

References 52 publications

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“…Medlyn et al, 2016). In addition, similar to other models (Goll et al, 2017;Yang et al, 2014), QUINCY v1.0 currently assumes that P limitation solely affects productivity due to a stoichiometric constraint on growth, while other mechanisms may also play an important role in the acclimation of plant processes to different levels of P availability (Jiang et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…the response of photosynthesis, tissue stoichiometry, and fine root growth to nutrient shortage, are assumed to have a process-specific "memory" timescale, causing a lagged response to instantaneous variations in the environmental conditions. This includes a representation of the acclimation of both photosynthesis and maintenance respiration to the prevailing growth temperature (June et al, 2004;Atkin et al, 2014;Mercado et al, 2018). Together with a dynamic representation of photosynthetic capacity based on soil nutrient availability, this feature reduces the need for regionally defined plant functional types (e.g.…”

Section: Introductionmentioning

confidence: 99%

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A new model of the coupled carbon, nitrogen, and phosphorus cycles in the terrestrial biosphere (QUINCY v1.0; revision 1996)

et al. 2019

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Abstract. The dynamics of terrestrial ecosystems are shaped by the coupled cycles of carbon, nitrogen, and phosphorus, and these cycles are strongly dependent on the availability of water and energy. These interactions shape future terrestrial biosphere responses to global change. Here, we present a new terrestrial ecosystem model, QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system), which has been designed from scratch to allow for a seamless integration of the fully coupled carbon, nitrogen, and phosphorus cycles with each other and also with processes affecting the energy and water balances in terrestrial ecosystems. This new model includes (i) a representation of plant growth which separates source (e.g. photosynthesis) and sink (growth rate of individual tissues, constrained by temperature and the availability of water and nutrients) processes; (ii) the acclimation of many ecophysiological processes to meteorological conditions and/or nutrient availability; (iii) an explicit representation of vertical soil processes to separate litter and soil organic matter dynamics; (iv) a range of new diagnostics (leaf chlorophyll content; 13C, 14C, and 15N isotope tracers) to allow for a more in-depth model evaluation. In this paper, we present the model structure and provide an assessment of its performance against a range of observations from global-scale ecosystem monitoring networks. We demonstrate that QUINCY v1.0 is capable of simulating ecosystem dynamics across a wide climate gradient, as well as across different plant functional types. We further provide an assessment of the sensitivity of key model predictions to the model's parameterisation. This work lays the ground for future studies to test individual process hypotheses using the QUINCY v1.0 framework in the light of ecosystem manipulation observations, as well as global applications to investigate the large-scale consequences of nutrient-cycle interactions for projections of terrestrial biosphere dynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A new model of the coupled carbon, nitrogen, and phosphorus cycles in the terrestrial biosphere (QUINCY v1.0; revision 1996)

et al. 2019

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“…However, a series of studies at leaf level showed a positive relationship between photochemical quenching and P in leaves as well as an effect of P on active fluorescence measurements [57]; these support the differences in LUE f observed in our study. Our study suggests that P, and in particular the co-limitation N and P, might have an important role on determining F 760 but is not conclusive on the mechanism, and more research is needed to understand the mechanism and also to support the current efforts to include P in terrestrial biosphere and photosynthesis models [27]. The fact that the magnitude of increase of Fesc fw is very similar in N and NP treatments support the idea that N addition is the main factor regulating canopy structure (Fesc fw and APAR).…”

Section: Treatment Effect On Lue P Lue F Fesc Fwmentioning

confidence: 77%

“…Moreover, there is a lack of studies that investigate at canopy scale how LUE p , LUE f , and Fesc are modulated under varying nitrogen availability [14]. Canopy phosphorous concentration (hereafter P%) is another critical element for photosynthesis, being involved in the synthesis of Adenosine triphosphate (ATP) [27]. Leaf-level studies with active fluorescence measurements showed that P% deficient plants have lower chlorophyll fluorescence emission efficiency [28].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen and Phosphorus Effect on Sun-Induced Fluorescence and Gross Primary Productivity in Mediterranean Grassland

et al. 2019

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Sun-Induced fluorescence at 760 nm (F760) is increasingly being used to predict gross primary production (GPP) through light use efficiency (LUE) modeling, even though the mechanistic processes that link the two are not well understood. We analyzed the effect of nitrogen (N) and phosphorous (P) availability on the processes that link GPP and F760 in a Mediterranean grassland manipulated with nutrient addition. To do so, we used a combination of process-based modeling with Soil-Canopy Observation of Photosynthesis and Energy (SCOPE), and statistical analyses such as path modeling. With this study, we uncover the mechanisms that link the fertilization-driven changes in canopy nitrogen concentration (N%) to the observed changes in F760 and GPP. N addition changed plant community structure and increased canopy chlorophyll content, which jointly led to changes in photosynthetic active radiation (APAR), ultimately affecting both GPP and F760. Changes in the abundance of graminoids, (%graminoids) driven by N addition led to changes in structural properties of the canopy such as leaf angle distribution, that ultimately influenced observed F760 by controlling the escape probability of F760 (Fesc). In particular, we found a change in GPP–F760 relationship between the first and the second year of the experiment that was largely driven by the effect of plant type composition on Fesc, whose best predictor is %graminoids. The P addition led to a statistically significant increase on light use efficiency of fluorescence emission (LUEf), in particular in plots also with N addition, consistent with leaf level studies. The N addition induced changes in the biophysical properties of the canopy that led to a trade-off between surface temperature (Ts), which decreased, and F760 at leaf scale (F760leaf,fw), which increased. We found that Ts is an important predictor of the light use efficiency of photosynthesis, indicating the importance of Ts in LUE modeling approaches to predict GPP.

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“…Such an imbalance may even partly explain the C that was missing in the budget established for our experiment by Klein et al (2016a). Indeed, P limitation decreases the efficiency of plant respiration (Jiang et al, 2019), and night respiration (that was not included in our C budget) may increase along the N/P ratio. Beside P, Mg nutrition is also a matter of concern because the N/Mg ratio was significantly higher in CO 2 -enriched trees, reaching values above the normal range.…”

Section: Discussionmentioning

confidence: 90%

Increased Nitrogen Availability in the Soil Under Mature Picea abies Trees Exposed to Elevated CO2 Concentrations

Schleppi

Körner

Klein

2019

Front. For. Glob. Change

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The response of trees to increasing atmospheric CO 2 concentrations is often mediated by the availability of nutrients. However, little is known about the influence of CO 2 enrichment on nutrient availability in forests with mature trees. We studied processes in the soil under five 35-m-tall Norway spruce trees (Picea abies) in NW Switzerland that were exposed to a mean CO 2 concentration of 550 ppm for 5 growing seasons using free air CO 2 enrichment (FACE). We compared them with values from the soil under five control trees. Ceramic suction cups were installed in the soil under each tree to collect soil solution, and ion-exchange resin bags were buried in the soil to absorb ammonium and nitrate. Soil cores taken at the end of the experiment were used to measure the gross production of ammonium and nitrate by the 15 N dilution technique. Although temporally and spatially variable, the nitrate concentration was higher in the soil solution under CO 2 -enriched trees. This effect was reflected in the resin bag extracts, which additionally indicated a trend of increased ammonium availability. Dissolved reduced N concentration (mainly dissolved organic N), however, was lower in the soil solution under CO 2 -enriched trees. K and Mg, and to a lesser extent Na and sulfate concentrations increased in the soil solution. P concentrations mostly remained below the detection limit. In spite of the higher concentrations of nitrate in soil extracts, gross N mineralization and nitrification rates were not affected by FACE. Needles from CO 2 -enriched trees contained slightly more N. No difference was observed for other nutrients. Overall, these results support the hypothesis of a priming effect, i.e., that FACE led to the production of more root exudates, which in turn stimulated soil biological activity, including mineralization, over a time-span of at least several years. However, these tall trees showed no growth response to elevated CO 2 ; hence, they gained no advantage from increased nitrate in the soil solution, presumably owing to other growth constraints including P and Mg availability.

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Towards a more physiological representation of vegetation phosphorus processes in land surface models

Cited by 72 publications

References 52 publications

A new model of the coupled carbon, nitrogen, and phosphorus cycles in the terrestrial biosphere (QUINCY v1.0; revision 1996)

A new model of the coupled carbon, nitrogen, and phosphorus cycles in the terrestrial biosphere (QUINCY v1.0; revision 1996)

Nitrogen and Phosphorus Effect on Sun-Induced Fluorescence and Gross Primary Productivity in Mediterranean Grassland

Increased Nitrogen Availability in the Soil Under Mature Picea abies Trees Exposed to Elevated CO2 Concentrations

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