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| Titel |
A sub-canopy structure for simulating oil palm in the Community Land Model (CLM-Palm): phenology, allocation and yield |
| VerfasserIn |
Y. Fan, O. Roupsard, M. Bernoux, G. Le Maire, O. Panferov, M. M. Kotowska, A. Knohl |
| 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. 11 ; Nr. 8, no. 11 (2015-11-26), S.3785-3800 |
| Datensatznummer |
250116670
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| Publikation (Nr.) |
 copernicus.org/gmd-8-3785-2015.pdf |
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| Zusammenfassung |
| In order to quantify the effects of forests to oil palm conversion occurring
in the tropics on land–atmosphere carbon, water and energy fluxes, we develop
a new perennial crop sub-model CLM-Palm for simulating a palm plant
functional type (PFT) within the framework of the Community Land Model
(CLM4.5). CLM-Palm is tested here on oil palm only but is meant of generic
interest for other palm crops (e.g., coconut). The oil palm has monopodial
morphology and sequential phenology of around 40 stacked phytomers, each
carrying a large leaf and a fruit bunch, forming a multilayer canopy. A
sub-canopy phenological and physiological parameterization is thus
introduced so that each phytomer has its own prognostic leaf growth and
fruit yield capacity but with shared stem and root components. Phenology and
carbon and nitrogen allocation operate on the different phytomers in parallel
but at unsynchronized steps, separated by a thermal period. An important
phenological phase is identified for the oil palm – the storage growth
period of bud and "spear" leaves which are photosynthetically inactive
before expansion. Agricultural practices such as transplanting,
fertilization and leaf pruning are represented. Parameters introduced for
the oil palm were calibrated and validated with field measurements of leaf
area index (LAI), yield and net primary production (NPP) from Sumatra,
Indonesia. In calibration with a mature oil palm plantation, the cumulative
yields from 2005 to 2014 matched notably well between simulation and
observation (mean percentage error = 3 %). Simulated inter-annual
dynamics of PFT-level and phytomer-level LAI were both within the range of
field measurements. Validation from eight independent oil palm sites shows
the ability of the model to adequately predict the average leaf growth and
fruit yield across sites and sufficiently represent the significant nitrogen-
and age-related site-to-site variability in NPP and yield. Results also
indicate that seasonal dynamics of yield and remaining small-scale
site-to-site variability of NPP are driven by processes not yet implemented
in the model or reflected in the input data. The new sub-canopy structure and
phenology and allocation functions in CLM-Palm allow exploring the effects of
tropical land-use change, from natural ecosystems to oil palm plantations, on
carbon, water and energy cycles and regional climate. |
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