5. Conclusions
We studied how the combination of terracing and mulching influences water use by jujube trees and their response to droughts in three different years on the semiarid Loess Plateau of China. We found that both the extreme and moderate droughts clearly reduced soil water storage and modified soil water use patterns, causing a sharp increase in the use of water from deep layers. Furthermore, the extreme rather than moderate drought resulted in a significant decrease in transpiration at both seasonal and annual scales. In addition, the jujube trees exhibited isohydric behavior during the drought periods; this allowed them to cope with extreme drought. Moreover, the combined treatments effectively enhanced soil water availability, deep-layer soil water and canopy transpiration, indicating higher water use efficiency than with traditional land management. These results demonstrate that the combination of terracing and mulching can help jujube trees to survive extreme droughts. These findings provide insights into the effective management of hillslope plantations in drylands, particularly in the context of global warming.