Towards the systematic simplification of mechanistic models

Cox, G.; Wood, Andrew; Craigon, J.; Ramsden, Stephen J.; Crout, N.M.J.

doi:10.1016/j.ecolmodel.2006.04.016

Cited by 130 publications

(55 citation statements)

References 15 publications

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“…The most suitable model was identified based on Akaikes Information Criterion (AIC) for each model version. Such an approach is in line with general parameter estimation procedures (Cox et al, 2006) and has been successfully used for parameter estimation with this 15 N tracing model (e.g. Müller et al, 2009;Rütting et al, 2011;Zhang et al, 2011).…”

Section: Calculation Procedures Statistics and Presentation Of Resultsmentioning

confidence: 82%

Effects of repeated fertilizer and cattle slurry applications over 38 years on N dynamics in a temperate grassland soil

Müller

Laughlin²,

Christie³

et al. 2011

Soil Biology and Biochemistry

120

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The effects of repeated synthetic fertilizer or cattle slurry applications at annual rates of 50, 100 or 200 m 3 ha À1 yr À1 over a 38 year period were investigated with respect to herbage yield, N uptake and gross soil N dynamics at a permanent grassland site. While synthetic fertilizer had a sustained and constant effect on herbage yield and N uptake, increasing cattle slurry application rates increased the herbage yield and N uptake linearly over the entire observation period. Cattle slurry applications, two and four times the recommended rate (50 m 3 ha À1 yr À1 , 170 kg N ha À1 ), increased N uptake by 46 and 78%, respectively after 38 years. To explain the long-term effect, a 15 N tracing study was carried out to identify the potential change in N dynamics under the various treatments. The analysis model evaluated process-specific rates, such as mineralization, from two organic-N pools, as well as nitrification from NH 4 þ and organic-N oxidation. Total mineralization was similar in all treatments. However, while in an unfertilized control treatment more than 90% of NH 4 þ production was related to mineralization of recalcitrant organic-N, a shift occurred toward a predominance of mineralization from labile organic-N in the cattle slurry treatments and this proportion increased with the increase in slurry application rate. Furthermore, the oxidation of recalcitrant organic-N shifted from a predominant NH 4 þ production in the control treatment, toward a predominant NO 3 À production (heterotrophic nitrification) in the cattle slurry treatments. The concomitant increase in heterotrophic nitrification and NH 4 þ oxidation with increasing cattle slurry application rate was mainly responsible for the increase in net NO 3 À production rate. Thus the increase in N uptake and herbage yield on the cattle slurry treatments could be related to NO 3 À rather than NH 4 þ production. The 15 N tracing study was successful in revealing process-specific changes in the N cycle in relationship to long-term repeated amendments.

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Section: Calculation Procedures Statistics and Presentation Of Resultsmentioning

confidence: 82%

Effects of repeated fertilizer and cattle slurry applications over 38 years on N dynamics in a temperate grassland soil

Müller

Laughlin²,

Christie³

et al. 2011

Soil Biology and Biochemistry

120

View full text Add to dashboard Cite

show abstract

“…The final model was identified based on Aikaike's information criterion (AIC) (the smallest AIC) (Cox et al, 2006). Initially, all parameters (N pools and N transformations) from the conceptual model (Fig.…”

Section: Figmentioning

confidence: 99%

Are nitrate production and retention processes in subtropical acidic forest soils responsive to ammonium deposition?

Gao

Kou

Yang

et al. 2016

Soil Biology and Biochemistry

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N tracing model Acid soil of subtropical forest a b s t r a c tChanges in soil N-cycling and retention processes in subtropical/tropical acidic forest ecosystems under anthropogenic N inputs are not well understood. We conducted a laboratory 15 N tracing study on an acid soil (pH values: 4.6 to 5.0) from a subtropical forest fertilized for more than 2.5 years at a rate of 0, 40, and 120 kg NH 4 CleN ha À1 yr À1 , respectively. To get a better resolution of mechanistic changes in soil N cycling and retention processes under NH 4 þ additions, we used a conceptual 15 N tracing model to quantify process-specific and pool-specific N transformation rates in soils. Gross N mineralization rates decreased at high NH 4 þ additions, which were paralleled by a reduction in fungal biomass and mineralization of recalcitrant organic N. Gross NH 4 þ immobilization rates did not show a change with increasing NH 4 þ additions. Interestingly, soil NO 3 À production (heterotrophic, autotrophic, and gross nitrification) and retention (NO 3 À immobilization and dissimilatory nitrate reduction to ammonium) showed insensitivity to increasing additions of NH 4 þ . The mechanisms behind the lack of response of heterotrophic nitrification were unclear, but possibly related to the absence of significant changes in soil C: N ratio and soil acidity under increased NH 4 þ additions. Because of the low autotrophic nitrification potential and the lack of NH 4 þ limitation to autotrophic nitrifiers, autotrophic nitrification was unresponsive to NH 4 þ additions.NO 3 À immobilization rates appeared to be controlled by the NO 3 À produced from heterotrophic nitrification, as indicated by the positive relationship between NO 3 À immobilization and heterotrophic nitri-thus showing a lack of a change under increased NH 4 þ additions. DNRA seemed to be inherently less responsive to environmental changes such as NH 4 þ deposition. Our work demonstrates that enhanced NH 4 þ deposition has a low potential to stimulate soil NO 3 À production and weaken soil retention of NO 3 À in this, and perhaps other subtropical/tropical acidic forest ecosystems.

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“…Thus, a mechanistic model will stay mechanistic. The same methodological divergence appears when comparing our work with some other systematic simplification methods [12,14,18]. Eventually, we underline how far the classification given by a regression tree approach is useful to understand how some parameters shape the distribution of the outputs.…”

Section: Comparison With Other Simplification and Reduction Methodsmentioning

confidence: 89%

Towards a simplification of models using regression trees

Eynaud

Nérini

Baklouti

et al. 2013

J. R. Soc. Interface.

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Over-parametrization in modelling is a well-known issue that makes it hard to identify which part of a model is responsible for a given behaviour. In line with that ascertainment, this work presents the outline of an empirical method to simplify models by decreasing the number of parameters. By using regression trees to classify outputs according to related input parameters, the method provides the modeller with an objective tool to reduce the range of the used parameters and, under certain conditions, to establish relations between them. Thereby, the complexity of the model is reduced on the basis of mathematical arguments. As an example, a dynamic energy budget-based model of a mesopelagic bacterial ecosystem is simplified using the presented method. The main benefits of such a method are thus highlighted: (i) more robust parameter estimations; (ii) less complex formulations; and (iii) fewer modelling assumptions. To conclude, the difficulties encountered are discussed, and several solutions are proposed to deal with them.

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Towards the systematic simplification of mechanistic models

Cited by 130 publications

References 15 publications

Effects of repeated fertilizer and cattle slurry applications over 38 years on N dynamics in a temperate grassland soil

Effects of repeated fertilizer and cattle slurry applications over 38 years on N dynamics in a temperate grassland soil

Are nitrate production and retention processes in subtropical acidic forest soils responsive to ammonium deposition?

Towards a simplification of models using regression trees

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