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| Titel |
Comparison of different tree sap flow up-scaling procedures using Monte-Carlo simulations |
| VerfasserIn |
Fyodor Tatarinov, Yakir Preisler, Shani Roahtyn, Dan Yakir |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109258
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| Publikation (Nr.) |
 EGU/EGU2015-9151.pdf |
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| Zusammenfassung |
| An important task in determining forest ecosystem water balance is the estimation of stand
transpiration, allowing separating evapotranspiration into transpiration and soil
evaporation. This can be based on up-scaling measurements of sap flow in representative
trees (SF), which can be done by different mathematical algorithms. The aim of
the present study was to evaluate the error associated with different up-scaling
algorithms under different conditions. Other types of errors (such as, measurement
error, within tree SF variability, choice of sample plot etc.) were not considered
here.
A set of simulation experiments using Monte-Carlo technique was carried out and three
up-scaling procedures were tested. (1) Multiplying mean stand sap flux density based on unit
sapwood cross-section area (SFD) by total sapwood area (Klein et al, 2014); (2) deriving of
linear dependence of tree sap flow on tree DBH and calculating SFstand using predicted SF
by DBH classes and stand DBH distribution (Cermak et al., 2004); (3) same as method 2 but
using non-linear dependency. Simulations were performed under different SFD(DBH) slope
(bs, positive, negative, zero); different DBH and SFD standard deviations (δd and δs,
respectively) and DBH class size. It was assumed that all trees in a unit area are measured and
the total SF of all trees in the experimental plot was taken as the reference SFstand
value.
Under negative bs all models tend to overestimate SFstand and the error increases
exponentially with decreasing bs. Under bs >0 all models tend to underestimate SFstand, but
the error is much smaller than for bs |
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