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| Titel |
The influence of soils on heterotrophic respiration exerts a strong control on net ecosystem productivity in seasonally dry Amazonian forests |
| VerfasserIn |
J. R. Melton, R. K. Shrestha, V. K. Arora |
| 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. 4 ; Nr. 12, no. 4 (2015-02-24), S.1151-1168 |
| Datensatznummer |
250117828
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| Publikation (Nr.) |
 copernicus.org/bg-12-1151-2015.pdf |
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| Zusammenfassung |
| Net ecosystem productivity of carbon (NEP) in seasonally dry forests
of the Amazon varies greatly between sites with similar
precipitation patterns. Correctly modeling the NEP seasonality with
terrestrial ecosystem models has proven difficult. Previous
modelling studies have mostly advocated for incorporating processes that
act to reduce water stress on gross primary productivity (GPP)
during the dry season, such as deep soils and roots,
plant-mediated hydraulic redistribution of soil moisture, and
increased dry season leaf litter generation which reduces leaf age
and thus increases photosynthetic capacity. Recent observations,
however, indicate that seasonality in heterotrophic respiration also
contributes to the observed seasonal cycle of NEP. Here, we use the
dynamic vegetation model CLASS-CTEM (Canadian Land
Surface Scheme–Canadian Terrestrial
Ecosystem Model) – without deep soils or roots,
hydraulic redistribution of soil moisture, or increased dry season
litter generation – at two Large-Scale Biosphere–Atmosphere
Experiment (LBA) sites (Tapajós km 83 and Jarú
Reserve). These LBA sites exhibit opposite seasonal NEP cycles
despite reasonably similar meteorological conditions. Our simulations are able
to reproduce the observed NEP seasonality at both sites. Simulated
GPP, heterotrophic respiration, latent and sensible heat fluxes,
litter fall rate, soil moisture and temperature, and basic
vegetation state are also compared with available observation-based
estimates which provide confidence that overall the model behaves
realistically at the two sites.
Our results indicate that
representing the effect of soil moisture on heterotrophic respiration in terms of soil matric potential and constraining
heterotrophic respiration when absolute soil matric potential is both low (wetter soils) and high (drier soils), with optimum conditions in between, allows
%appropriately representing the influence of soil texture and depth,
%through soil moisture, on seasonal patterns of GPP and, especially,
% heterotrophic respiration is important
to correctly simulate NEP
seasonality. |
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