A whole-plant perspective of hydraulic strategy in temperate desert shrub species.

Desert shrubs play a crucial role in controlling desertification and promoting revegetation, but drought often hinders their growth. Investigating the hydraulic strategies of desert shrubs is important in order to understand their drought adaptation and predict future dynamics under climate change. In this study, we measured the hydraulic-related characteristics of roots, stems and leaves in 19 desert shrub species from northern China. We aimed to explore the hydraulic coordination and segmentation between different plant organs. The results were as follows: (i) specific root length was positively correlated with the water potential inducing a 50% loss in stem hydraulic conductivity (P50stem) and negatively correlated with stem hydraulic safety margin. This suggested that water uptake efficiency of the fine roots was traded off with stem embolism resistance and hydraulic safety. (ii) The water potential inducing a 50% loss in leaf hydraulic conductance was significantly less negative than P50stem, and fine root turgor loss point was significantly less negative than P50stem, indicating a hydraulic segmentation between the main stem and terminal organs. (iii) The most negative leaf turgor loss point indicated that leaf wilting occurred after substantial leaf and stem embolism. The high desiccation resistance of the leaves may serve as an important physiological mechanism to increase carbon gain in a relatively brief growth period. In summary, this study elucidated the hydraulic strategies employed by desert shrubs from a whole-plant perspective.