Impact of land management practices on water use strategy for a dryland tree plantation and subsequent responses to drought

Abstract Extreme droughts, of increased frequency due to climate change, are threatening the sustainability of dryland plantations worldwide by exacerbating water scarcity. Here we aim to disentangle the impacts of combinations of terracing and mulching on water use strategy and their response to extreme droughts in a rainfed jujube ( Ziziphus jujuba Mill.) plantation on the semiarid Loess Plateau of China, using 3‐year in situ field observations. Pruned jujube branches and maize straw were mulched on half‐moon terraces to form two combined treatments, referred to as JBT and MST, respectively. The efficacy of these two combinations on the water use strategy of jujube trees was compared with terracing alone (SHT) and control (no terrace). We found that under extreme drought there was clearly reduced soil water storage (SWS) for different treatments. However, the combined treatments showed significantly ( p < .05) higher SWS than the SHT and control. Furthermore, the combined treatments enhanced soil water use in deep layers during both normal and drought years, thus helping jujube trees to resist droughts. Moreover, under extreme drought there was greatly reduced transpiration whereas for moderate drought increased transpiration at both seasonal and annual scales. Nonetheless, the combined treatments were associated with enhanced transpiration compared to the SHT and control during drought periods. Finally, jujube trees exhibited isohydric behavior which also helped them to cope with prolonged droughts. Overall, the findings here may provide insights into land management of dryland plantations worldwide under climate change.