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Gewählte Master / Diploma Thesis:

Josef Gadermaier (2017): Effect of artificial drought stress on sap flow of different tree species in the eastern Himalaya.
Master / Diploma Thesis - Institut für Botanik (Botany), BOKU-Universität für Bodenkultur, pp 72. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Ongoing climate change may result in more frequent monsoon failures in the future. This would cause severe droughts in the affected areas and lead to changes in the ecosystems. To simulate such a drought, four through-fall exclusion plots, covering a total area of 2.400 m2, were established in two main Bhutanese forest types in 2014 and compared with control plots receiving normal rainfall. Additionally, climate and soil water were monitored. In this study, data from sap flow sensors on 60 trees from five tree species are evaluated. The five tree species include one conifer (Tsuga dumosa) three oak species differing in phenology (Quercus griffithi – deciduous, Quercus lanata and Quercus semecarpifolia – evergreen) and one Rhododendron species in the understorey (Rhododendron arboreum). The analysis of sap flow data with soil moisture and climate from the different sites and plots shows the different reactions of tree species to the simulated drought. During the measurement period (three months in 2016), two species (Rhododendron arboreum and Quercus lanata) showed no differences between trees on the control plots and the through-fall exclusion plots. During the monsoon season, in the other species the drought-stressed trees had significantly lower sap flow. In the following dry period, with higher vapour pressure deficit of the, this difference increased. The time-lag between the driving climate parameters and sap flow was greatest in Tsuga dumosa, suggesting that this species has a relatively high stem water storage capacitance. For a better understanding of the resilience to drought of the species studied, in the future longer sap flow time series should be analysed together with additional data of the trees.

Beurteilende(r): Hietz Peter
1.Mitwirkender: Gratzer Georg

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