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| Titel |
Scaling from individual trees to forests in an Earth system modeling framework using a mathematically tractable model of height-structured competition |
| VerfasserIn |
E. S. Weng, S. Malyshev, J. W. Lichstein, C. E. Farrior, R. Dybzinski, T. Zhang, E. Shevliakova, S. W. Pacala |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 9 ; Nr. 12, no. 9 (2015-05-07), S.2655-2694 |
| Datensatznummer |
250117925
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| Publikation (Nr.) |
 copernicus.org/bg-12-2655-2015.pdf |
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| Zusammenfassung |
| The long-term and large-scale dynamics of ecosystems are in large part
determined by the performances of individual plants in competition with one
another for light, water, and nutrients. Woody biomass, a pool of carbon (C)
larger than 50% of atmospheric CO2, exists because of
height-structured competition for light. However, most of the current Earth
system models that predict climate change and C cycle feedbacks lack both a
mechanistic formulation for height-structured competition for light and an
explicit scaling from individual plants to the globe. In this study, we
incorporate height-structured competition for light, competition for water,
and explicit scaling from individuals to ecosystems into the land model
version 3 (LM3) currently used in the Earth system models developed by the
Geophysical Fluid Dynamics Laboratory (GFDL). The height-structured
formulation is based on the perfect plasticity approximation (PPA), which
has been shown to accurately scale from individual-level plant competition
for light, water, and nutrients to the dynamics of whole communities. Because
of the tractability of the PPA, the coupled LM3-PPA model is able to include
a large number of phenomena across a range of spatial and temporal scales
and still retain computational tractability, as well as close linkages to
mathematically tractable forms of the model. We test a range of predictions
against data from temperate broadleaved forests in the northern USA. The
results show the model predictions agree with diurnal and annual C fluxes,
growth rates of individual trees in the canopy and understory, tree size
distributions, and species-level population dynamics during succession. We
also show how the competitively optimal allocation strategy – the strategy
that can competitively exclude all others – shifts as a function of the
atmospheric CO2 concentration. This strategy is referred to as an
evolutionarily stable strategy (ESS) in the ecological literature and is
typically not the same as a productivity- or growth-maximizing strategy.
Model simulations predict that C sinks caused by CO2 fertilization in
forests limited by light and water will be down-regulated if allocation
tracks changes in the competitive optimum. The implementation of the model
in this paper is for temperate broadleaved forest trees, but the formulation
of the model is general. It can be expanded to include other growth forms
and physiologies simply by altering parameter values. |
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