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| Titel |
Evaluation of Water Use Efficiency of Short Rotation Poplar Coppice at Bohemian-Moravian Highlands |
| VerfasserIn |
Marcela Hlaváčová, Milan Fischer, Abhishek Mani Tripathi, Matěj Orság, Miroslav Trnka |
| 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 |
250109704
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| Publikation (Nr.) |
 EGU/EGU2015-9640.pdf |
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| Zusammenfassung |
| The water availability of the locality constitutes one of the main constraint for short rotation
coppices grown on arable land. As a convenient characteristic assessing how the water use is
coupled with the biomass yields, so called water use efficiency (WUE) is proposed. One
method of water use efficiency determination is presented within this study. The study was
carried out at short rotation poplar coppice (poplar clone J-105) at the Test Station
Domanínek, Ltd. at Bohemian-Moravian Highlands during the growing season 2013.
Diameters at breast height (DBH) were measured for 16 sample trees where sap flow
measuring systems (Granier’s Thermal Dissipation Probe, TDP) were installed. TDP
outputs are expressed as temperature differences (δT) between the heated and
non-heated probes. Estimation of sap flux density (Fd) by the Granier method relies
on the measurement of temperature difference (δT). Determination of maximum
temperature difference (δTmax) is fundamental for sap flux density (Fd) calculation.
Although δTmax can be theoretically defined as δT at Fd = 0, many factors may
prevent the occurrence of the zero flow state, such as night-time water movement for
new growth (vegetative or reproductive) or water loss from the canopy due to high
vapour pressure deficit (VPD). Therefore, the VPD condition was established for
determination of δTmax. VPD condition was established as follows: VPD reaching
values 0.2 at least 6 hours during night (from 21 p. m. to 3 a. m. and when the
condition was fullfilled, the value at 3 a. m. was taken) because it is a supposed
time after that the tree has no transpiration. The programmable part of Mini 32
software (www.emsbrno.cz) was used for application of the script establishing δTmax
values under this VPD condition. Nevertheless, another script was applied on δT
data set to determination of δTmax values for every night at 3 a. m. (as this is
when δT should be at its daily maximum) without VPD condition restriction for
comparison of both approaches. Since application of the two mentioned scripts
led to two sets of resulting values, calculations of Fd and consequent sap flow
values were computed for both variants of δTmaxvalues. The sample trees were
divided into 3 diameter classes according to DBH values at the beginning of regular
measurements (April 24, 2013). Allometry was carried out on February 20, 2014 to
calculation of aboveground woody biomass. The input data for calculations of WUE of
aboveground woody biomass productivity was biomass increments and monthly
totals of sap flow for 16 sample trees. The total WUE for 16 measured trees reached
4.93 g kg-1 (when calculated with data set without VPD condition) and 4.63 g
kg-1 (when calculated with data set under VPD condition). This study was funded
by project "Building up a multidisciplinary scientific team focused on drought"
No. CZ.1.07/2.3.00/20.0248 and LD130030 supporting COST Action ES1106. |
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