Water consumption of Populus alba trees in tree shelterbelt systems in Central Asia – a case study in the Chui Valley, South Eastern Kazakhstan

Agriculture in Central Asia largely relies on irrigation. The water is withdrawn from the rivers of the region, which predominantly originate from snowfields and glaciers. Due to the global warming these water resources are expected to decline substantially, resulting in an aggravation of the already existing water scarcity. Tree shelterbelt systems as the most prominent practice of agroforestry in Central Asia are reported to help to reduce water consumption in irrigated agriculture. Though, studies about water consumption of the shelterbelts are lacking. Therefore, the objectives of this study are to investigate (1) the water consumption of Populus alba trees in a shelterbelt system in Central Asia and (2) analyze the influence of the local climatic conditions on the sap flow of such a shelterbelt. P. alba is one of the most important shelterbelt trees in Central Asia. Tree water consumption was assessed through sap flow measurements on three trees in a crop shelterbelt system in the Chui Valley in SE Kazakhstan during June and July 2016. The average daily water consumption were 187.6 l/d, 44.8 l/d, and 160 l/d for the trees, respectively. These results were extrapolated for a representative shelterbelt section. Water consumption of that section was 7.8 mm/d, while average ETo was 5.3 mm/d. Considerable influences of water vapor saturation deficit, air temperature and relative humidity on the sap flow could be observed. Solar radiation played a role, too, whereas little or no influence for wind speed was found.