Dataset Information

Tree xylem water isotope analysis by Isotope Ratio Mass Spectrometry and laser spectrometry: A dataset to explore tree response to drought.

ABSTRACT: Water isotopes from plant xylem and surrounding environment are increasingly used in eco-hydrological studies. Carrière et al. [1] analyzed a dataset of water isotopes in (i) the xylem of three different tree species, (ii) the surrounding soil and drainage water and (iii) the underlying karst groundwater, to understand tree water uptake during drought in two different Mediterranean forests on karst setting. The xylem and soil water were extracted by cryogenic distillation. The full dataset was obtained with Isotope Ratio Mass Spectrometry (IRMS) and Isotope Ratio Infrared Spectrometer (IRIS), and included 219 measurements of δ2H and δ18O. Prompted by unexpected isotopic data characterized by a very negative deuterium excess, a subsample of 46 xylem samples and 9 soil water samples were double checked with both analytical techniques. IRMS and IRIS analyses yielded similar data. Therefore, the results reveal that laser spectrometry allows an accurate estimation of xylem and soil water isotopes. The dataset highlights a strong 2H depletion in xylem water for all species. Deuterium does not seem adequate to interpret ecological processes in this dataset given the strong fractionation.

SUBMITTER: Carriere SD

PROVIDER: S-EPMC7066053 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:How the mortality and growth of tree species vary with the iso-anisohydric continuum and xylem vulnerability is still being debated. We conducted a precipitation reduction experiment to create a mild drought condition in a forest in the Baotianman Mountains, China, a sub-humid region. Three main sub-canopy tree species in this region were examined. After rainfall reduction, Lindera obtusiloba showed severe dieback, but two other co-occurring species did not show dieback. The water potential at stomatal closure of Dendrobenthamia japonica, L. obtusiloba and Sorbus alnifolia was -1.70, -2.54 and -3.41 MPa, respectively, whereas the water potential at 88 % loss in hydraulic conductivity of the three species was -2.31, -2.11 and -7.01 MPa, respectively. Taken together, near-anisohydric L. obtusiloba with vulnerable xylem was highly susceptible to drought dieback. Anisohydric S. alnifolia had the most negative minimum water potential, and its xylem was the most resistant to cavitation. Isohydric D. japonica conserved water by rapidly closing its stomata. Ultimately, the hydraulic safety margin (HSM) of L. obtusiloba was the smallest among the three species, especially in precipitation-reduced plots. In terms of the stomatal safety margin (SSM), L. obtusiloba was negative, while S. alnifolia and D. japonica were positive. Of the two species without dieback, rainfall reduction decreased growth of D. japonica, but did not influence growth of S. Alnifolia; meanwhile, rainfall reduction led to a decrease of non-structural carbohydrates (NSCs) in D. japonica, but an increase in S. alnifolia. It is concluded that HSM as well as SSM allow interpreting the sensitivity of the three sub-canopy species to drought. The drought-induced dieback of L. obtusiloba is determined by the interaction of stomatal behaviour and xylem vulnerability, and the species could be sensitive to climate change-caused drought although still in sub-humid areas. The isohydric/anisohydric degree is associated with NSCs status and growth of plants.

Dataset Information

Tree xylem water isotope analysis by Isotope Ratio Mass Spectrometry and laser spectrometry: A dataset to explore tree response to drought.

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