Vulnerability to drought-induced cavitation in shoots of two typical shrubs in the southern Mu Us Sandy Land, China
LI Yangyang1,2*, CHEN Weiyue3, CHEN Jiacun2, SHI Hui4
1 State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, China; 2 Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100, China; 3 College of Forestry, Northwest A&F University, Yangling 712100, China; 4 School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, China
AbstractSalix psammophila and Caragana korshinskii are two typical shrubs in the southern Mu Us Sandy Land of China which are threatened by increasing water deficits related to climate change and large-scale human activities (e.g. coal mining and oil exploitation). In this study, we assessed their vulnerability to xylem embolism and the related anatomical traits in two-year-old regenerated shoots of these two shrubs to understand how they cope with drought environment. We also evaluated the in situ hydraulic safety margins to hydraulic failure from measurements of annual predawn and midday leaf water potentials. The results showed that S. psammophila stems had a higher water transport capacity than C. korshinskii stems. The stem xylem water potentials at 12%, 50% and 88% loss of conductivity were –1.11, –1.63 and –2.15 MPa in S. psammophila, respectively, and –1.37, –2.64 and –3.91 MPa in C. korshinskii, respectively. This suggested that C. korshinskii was more resistant to cavitation than S. psammophila. Compared with S. psammophila, C. korshinskii had shorter maximum vessel length, lower vessel density, smaller conductive area and higher wood density, which may contribute to its more resistant xylem. The in situ hydraulic safety margins indicated that even during the driest periods, both shrubs lived well above the most critical embolism thresholds, and the hydraulic safety margin was wider in C. korshinskii than in S. psammophila, suggesting that the regenerated shoots of both shrubs could function normally and C. korshinskii had greater hydraulic protection. These results provide the basis for an in-depth understanding of the survival, growth and functional behavior of these two shrubs under harsh and dry desert environments.
LI Yangyang, CHEN Weiyue, CHEN Jiacun, SHI Hui. Vulnerability to drought-induced cavitation in shoots of two typical shrubs in the southern Mu Us Sandy Land, China. Journal of Arid Land, 2016, 8(1): 125-137.
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