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| Titel |
Modelling climate change responses in tropical forests: similar productivity estimates across five models, but different mechanisms and responses |
| VerfasserIn |
L. Rowland, A. Harper, B. O. Christoffersen, D. R. Galbraith, H. M. A. Imbuzeiro, T. L. Powell, C. Doughty, N. M. Levine, Y. Malhi, S. R. Saleska, P. R. Moorcroft, P. Meir, M. Williams |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 8, no. 4 ; Nr. 8, no. 4 (2015-04-21), S.1097-1110 |
| Datensatznummer |
250116280
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| Publikation (Nr.) |
 copernicus.org/gmd-8-1097-2015.pdf |
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| Zusammenfassung |
Accurately predicting the response of Amazonia to climate change is
important for predicting climate change across the globe. Changes in
multiple climatic factors simultaneously result in complex non-linear
ecosystem responses, which are difficult to predict using vegetation models.
Using leaf- and canopy-scale observations, this study evaluated the
capability of five vegetation models (Community Land Model version 3.5 coupled to the Dynamic Global Vegetation model – CLM3.5–DGVM; Ecosystem Demography model version 2 – ED2; the Joint UK Land
Environment Simulator version 2.1 – JULES; Simple Biosphere model
version 3 – SiB3; and the soil–plant–atmosphere model – SPA) to
simulate the responses of leaf- and canopy-scale productivity to changes in
temperature and drought in an Amazonian forest.
The models did not agree as to whether gross primary productivity (GPP) was
more sensitive to changes in temperature or precipitation, but all the
models were consistent with the prediction that GPP would be higher if
tropical forests were 5 °C cooler than current ambient
temperatures. There was greater model–data consistency in the response of
net ecosystem exchange (NEE) to changes in temperature than in the response
to temperature by net photosynthesis (An), stomatal conductance
(gs) and leaf area index (LAI). Modelled canopy-scale fluxes are
calculated by scaling leaf-scale fluxes using LAI. At the leaf-scale, the
models did not agree on the temperature or magnitude of the optimum points
of An, Vcmax or gs, and model variation in these parameters was
compensated for by variations in the absolute magnitude of simulated LAI
and how it altered with temperature.
Across the models, there was, however, consistency in two leaf-scale
responses: (1) change in An with temperature was more closely linked to
stomatal behaviour than biochemical processes; and (2) intrinsic water use
efficiency (IWUE) increased with temperature, especially when combined with
drought. These results suggest that even up to fairly extreme temperature
increases from ambient levels (+6 °C), simulated photosynthesis
becomes increasingly sensitive to gs and remains less sensitive to
biochemical changes. To improve the reliability of simulations of the
response of Amazonian rainforest to climate change, the mechanistic
underpinnings of vegetation models need to be validated at both leaf- and
canopy-scales to improve accuracy and consistency in the quantification of
processes within and across an ecosystem. |
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