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Gewählte Doctoral Thesis:

Doctoral Thesis - Institut für Waldökologie (IFE), BOKU-Universität für Bodenkultur, pp 207. UB BOKU obvsg

Data Source: ZID Abstracts
The Himalayas are predicted to experience more than three times the mean global rise in temperature, as well as erratic rainfall patterns and an increased likelihood for total monsoon failures. While many ecosystem manipulation experiments aiming at understanding the effects of altered precipitation, temperature and CO2 are conducted globally, such experiments are rare in Asia and missing in the Himalayas. Thus, to fill this gap, we simulated late onset of the monsoon precipitation as well as total monsoon failures in a multi-year drought stress experiment in Bhutan. We applied two treatments, (1) throughfall exclusion and (2) ambient control plots. Two 725 m2 plots, each with two replicates, were set up in Hemlock (Tsuga dumosa) and Oak (Quercus lanata and Quercus griffithii) dominated ecosystems at 3260 and 2460 m altitude, respectively. Roof application reduced the volumetric soil water content in the upper 0-20 cm soil layer by ~ 20% in coniferous and by ~ 31% in broadleaved forest, but less in deeper soil. Soil CO2 efflux was comparable between the two forests (2015: 14.5 ± 1.2 t C yr-1 broadleaved; 12.8 ± 1.0 t C yr-1 coniferous). Annual contribution of autotrophic respiration was ~ 45% at both forests. Further results on plant water potentials and sap flux suggest that Oaks are better adapted to drought as the conifer species. Especially evergreen Oaks seem to be more drought tolerant compared to T. dumosa and R. arboreum. The results provide insights into impacts of climate change on future forest development and suggests management practices for the Bhutan Himalayas, as the drought tolerant and water saving strategies of the oaks may be a selective advantage over the conifer species. Besides, we could also demonstrate that large scale throughfall exclusion experiments can be successfully conducted even in a remote Bhutan Himalayan setting. The experiences gathered could be utilized for future longterm ecological monitoring studies in the Himalayan region

Betreuer: Gratzer Georg
1. Berater: Hietz Peter
2. Berater: Katzensteiner Klaus

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