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| Titel |
Seasonal variation in ecosystem parameters derived from FLUXNET data |
| VerfasserIn |
M. Groenendijk, M. K. van der Molen, A. J. Dolman |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250023684
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| Zusammenfassung |
| The carbon dioxide sink is related in a complex way to weather and climate. In order to better
understand the relationship and feedbacks, we present a methodology to simulate observed
carbon dioxide flux data with a simple vegetation model (5PM) with weekly varying model
parameters. The model parameters explain the interaction between vegetation and seasonal
climate more general than the flux data. Two parameters (Rref and E0) are related to
ecosystem respiration and three parameters (Jm, λ and α) to photosynthesis and
transpiration. We quantified the weekly variability of ecosystem parameters as a function of
vegetation type and climate region.
The objective of this paper is to quantify the short term variability of ecosystem
parameters of different vegetation types and climate regions. Specific questions we want to
address: (1) are the model parameters clearly different between PFTs and (2) do the model
parameters vary in an understandable way and (3) does the variation in model parameters
have implications for our understanding of the feedback between vegetation and
climate?
After statistical quality checks, 122 FLUXNET sites were available for analysis of the
weekly varying model parameters. The simulations of these sites have high correlation
coefficients (r2 = 0.6 to 0.8) between the observed and simulated carbon and water
fluxes. With weekly parameters we determined average seasonal cycles for the
different combinations of vegetation type and climate regions (PFTs). The variation
between PFTs is large, which provides an excellent dataset to study the differences
in ecosystem characteristics. In general we observed that needleleaf forests and
grasslands in warmer climates have relatively constant parameter values during the year.
Broadleaf forests in all climate regions have large seasonal variation for each of the five
parameters. In boreal regions parameter values are always lower than in temperate
regions.
A large seasonality of the model parameters indicates a strong relation between
vegetation and climate. This suggests that climate change will have the largest impact on the
terrestrial carbon fluxes in boreal regions and for deciduous forests, and less for grasslands
and evergreen forests. |
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