Acknowledgement
This work was jointly supported by the National Key Research and
Development Plan (No. 2016YFC0400204), the National Natural Science
Foundation of China (No. 41771316), and the ‘111’Project (No. B12007).
Abstract Extreme droughts of increased frequency due to climate
change poses great challenges to the sustainability of plantations in
drylands worldwide. Millions of plantations on China’s Loess Plateau
which are mainly in drylands are threatened by serious degradation due
to water scarcity. Here we aim to disentangle the impacts of
combinations of terracing and mulching on water use strategy and its
response to extreme droughts in a rainfed jujube (Ziziphus
jujuba ) plantation on the semiarid Loess Plateau, using three-yearin 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 extreme drought clearly reduced soil water storage (SWS) under all
treatments. However, the combined treatments showed significantly
(P <0.05) 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, the extreme drought significantly reduced
transpiration whereas the 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.
Key words : water source; soil moisture; transpiration; land
development; drought