Coordinated Adaptation Mechanism of Hydraulic Safety and Thermal Tolerance in Five Tamarix Species

doi:10.7525/j.issn.1673-5102.2026.04.004

Abstract

Abstract:

The increasing frequency of drought and heatwaves due to global climate change poses a severe threat to desert vegetation. However， the mechanisms by which desert shrubs coordinate hydraulic safety and thermal-tolerance to cope with compound drought-heat stress remain unclear. Five sympatric Tamarix species in the arid region of Northwest China were investigated in this study. By combining 24 h field measurements of gas exchange parameters and leaf water potential with the determinations of physiological traits（xylem embolism vulnerability（P₅₀）， turgor loss point（Ψ_tlp）， and semi-lethal high temperature（LT₅₀））， we systematically evaluated their adaptive strategies. The results showed that：（1）There was significant interspecific differentiation in drought and heat resistance among the five species. Tamarix hispida exhibited the strongest embolism resistance（P₅₀=-2.20 MPa） and thermal tolerance（LT₅₀=66.5 ℃）， while T. hohenackeri showed the highest gas exchange rates but the weakest resistance. （2）Thermal tolerance（LT₅₀） was significantly negatively correlated with embolism resistance（P₅₀） and significantly positively correlated hydraulic safety margins（H_SM）， confirming a high degree of coordinated adaptation rather than a trade-off between hydraulic safety and thermal tolerance in desert plants. （3）Principal Component Analysis（PC1 explained 92.4%） revealed a continuous spectrum of adaptive strategies： ranging from an “Acquisitive-Cooling” strategy represented by T.hohenackeri， to a “Conservative-Tolerance” strategy represented by T.hispida. This study reveals niche differentiation mechanisms based on hydraulic-thermal coupling and highlights the importance of prioritizing species with “Conservative-Tolerance” strategies for vegetation restoration under future hotter and drier climate scenarios.

Key words: Tamarix, hydraulic safety margin, thermal tolerance, xylem embolism, coordinated adaptation, compound drought-heat stress

CLC Number:

Q948.112

Xiaoke HU, Chenglin YUAN, Xiaona QIU, Zhaokang AN, Na LI, Fanglin WANG. Coordinated Adaptation Mechanism of Hydraulic Safety and Thermal Tolerance in Five Tamarix Species[J]. Bulletin of Botanical Research, 2026, 46(4): 613-625.

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物种 Species	株数 Plants	冠幅（东西向） Crown width （E-W）/m	冠幅（南北向） Crown width （N-S）/m	株高 Height/m	基径 Basal diameter/cm	枯枝率 Dead branch rate/%	死亡率 Mortality rate/%
多花柽柳 T.hohenackeri	15	1.78±0.02^a	1.50±0.04^a	1.71±0.03^a	3.30±0.03^a	45.97±0.89^a	20.00
长穗柽柳 T.elongata	13	1.70±0.03^a	1.37±0.03^ab	1.69±0.01^ab	3.08±0.03^b	39.79±0.56^b	15.38
多枝柽柳 T.ramosissima	13	1.57±0.03^b	1.45±0.04^ab	1.60±0.01^c	2.81±0.02^c	32.49±0.51^c	7.69
短穗柽柳 T.laxa	12	1.38±0.03^c	1.34±0.03^b	1.42±0.02^d	2.62±0.05^d	25.86±0.65^d	0
刚毛柽柳 T.hispida	12	1.43±0.03^c	1.34±0.02^b	1.61±0.02^bc	2.45±0.05^e	15.29±0.92^e	0