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| Titel |
Tree specific traits vs. stand level characteristics - assessing the source depths of plant water uptake in a mixed forest stand |
| VerfasserIn |
Stefan Seeger, Nadine Brinkmann, Ansgar Kahmen, Markus Weiler |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250152293
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| Publikation (Nr.) |
 EGU/EGU2017-17113.pdf |
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| Zusammenfassung |
| Due to differences in fine root distributions, physiological root characteristics and plant
plasticity, the spatial and temporal characteristics of plant water uptake are expected to vary
between different tree species. This has implications on the overall water budget of a forest
stand as well as on the drought sensitivity of particular trees. A four-year time series of
climate data, soil moisture, and stable water isotopes in soil and tree xylem was used to
investigate plant water uptake dynamics of four tree species (beech - Fagus sylvatica, spruce -
Picea abies, ash - Fraxinus excelsior and maple - Acer pseudoplatanus) in a mixed forest
stand. Modeling with a modified version of the soil hydrological model Hydrus-1D
allowed us to simulate continuous time series of stable water isotopes in plant water
uptake, which were compared to the measured values in tree xylem water and soil
water.
We found that different estimated species specific fine root distributions and root water
uptake parameters lead to very similar simulated water balances and soil water isotope depth
profiles for all four species. According to our simulations, differences in evaporative demand
(i.e. LAI) had the biggest influence on water uptake and soil water distributions. Comparing
the isotopic signatures of simulated root water uptake and measured xylem water, the
simulations for beech were most suited to predict the observed signatures of all four
species. This indicates that isolated, tree specific parametrized 1-D simulations are
not suited to predict actual water uptake of different trees in a mixed stand. Due
to overlapping root spaces dominant trees (in our case beeches with an LAI of
around 5.5) may influence the soil water storage below accompanying trees (spruces,
ashes and maples with LAIs between 1.8 and 3.1) in a degree that their actual water
uptake cannot be predicted with 1-D simulations based on their smaller LAI values.
Consequently, for a mixed forest stand the interplay of trees with different traits has to
be accounted for in order to correctly model plant water uptake of single trees. |
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