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| Titel |
Biogeophysical feedbacks trigger shifts in the modelled vegetation-atmosphere system at multiple scales |
| VerfasserIn |
S. C. Dekker, H. J. Boer, V. Brovkin, K. Fraedrich, M. J. Wassen, M. Rietkerk |
| 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 ; 7, no. 4 ; Nr. 7, no. 4 (2010-04-12), S.1237-1245 |
| Datensatznummer |
250004663
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| Publikation (Nr.) |
 copernicus.org/bg-7-1237-2010.pdf |
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| Zusammenfassung |
| Terrestrial vegetation influences climate by modifying the radiative-,
momentum-, and hydrologic-balance. This paper contributes to the ongoing
debate on the question whether positive biogeophysical feedbacks between
vegetation and climate may lead to multiple equilibria in vegetation and
climate and consequent abrupt regime shifts. Several modelling studies argue
that vegetation-climate feedbacks at local to regional scales could be
strong enough to establish multiple states in the climate system. An Earth
Model of Intermediate Complexity, PlaSim, is used to investigate the
resilience of the climate system to vegetation disturbance at regional to
global scales. We hypothesize that by starting with two extreme
initialisations of biomass, positive vegetation-climate feedbacks will keep
the vegetation-atmosphere system within different attraction domains.
Indeed, model integrations starting from different initial biomass
distributions diverged to clearly distinct climate-vegetation states in
terms of abiotic (precipitation and temperature) and biotic (biomass)
variables. Moreover, we found that between these states there are several
other steady states which depend on the scale of perturbation. From here
global susceptibility maps were made showing regions of low and high
resilience. The model results suggest that mainly the boreal and monsoon
regions have low resiliences, i.e. instable biomass equilibria, with
positive vegetation-climate feedbacks in which the biomass induced by a
perturbation is further enforced. The perturbation did not only influence
single vegetation-climate cell interactions but also caused changes in
spatial patterns of atmospheric circulation due to neighbouring cells
constituting in spatial vegetation-climate feedbacks. Large perturbations
could trigger an abrupt shift of the system towards another steady state.
Although the model setup used in our simulation is rather simple, our
results stress that the coupling of feedbacks at multiple scales in
vegetation-climate models is essential and urgent to understand the system
dynamics for improved projections of ecosystem responses to anthropogenic
changes in climate forcing. |
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