Determination of the water-use patterns for two xerophyte shrubs by hydrogen isotope offset correction

Tree Physiology, Journal Year: 2023, Volume and Issue: 44(1)

Published: Sept. 28, 2023

Abstract The stable hydrogen and oxygen isotope technique is typically used to explore plant water uptake; however, the accuracy of has been challenged by offsets between xylem its potential source water. In this study, soil waterline was correct for Salix psammophila Caragana korshinskii, two typical shrub species on Chinese Loess Plateau. Five different types isotopic data [(i) δ18O, (ii) δ2H, (iii) combination δ18O with (iv) corrected δ2H (v) δ2H] were separately determine water-use patterns shrubs. offset values S. C. korshinskii did not show significant temporal variation among sampling months (May, July September) but showed notable differences shrubs (−0.4 ± 0.5‰ in vs −4.3 0.9‰ korshinskii). obtained absorption proportion (WAP) layers (0–20, 20–60 60–200 cm) differ significantly five input types. However, compared (v), (i), overestimated WAP 0–20 cm layer underestimated that layer. type (25.9 0.8%) comparison calculated based (19.1 1.1%). i.e., identified as best use due strong correlation content sand content. general, mainly (57.9–62.1%) shallow (0–60 cm), whereas absorbed (52.7–63.5%) deep (60–200 cm). We confirm can cause errors determining uptake provide valuable insights accurately quantifying presence This study facilitating application worldwide, revealing response mechanism key ecohydrological physiological processes drought environment similar climate regions.

Language: Английский

Reply on RC2

Published: Oct. 12, 2023

Abstract. While reforestation in water-limited areas has increased vegetation coverage, an increasing number of studies have reported that large-scale plantations are suffering from tree degradation, which is characterized by short trees, small size, and dieback. Moreover, the changes hydrological processes degraded trees within soil-plant system remain poorly understood. Here, stable isotope method (²H, ¹⁸O, ¹³C) thermal dissipation technique were used to compare soil water dynamics, transpiration, root uptake patterns, intrinsic water-use efficiency (WUE_i) Populus simonii under different degradation degrees (no ND; light LD; or severe SD) 2021 growing season. As intensified, weight density decreased significantly (P<0.05) proportion shallow layer (0–40 cm) increased. Influenced precipitation recharge, volumetric content (SWC) did not show significant differences (P>0.05) among degrees. The SWC middle (40–80 deep (80–200 layers lower ND plot than LD SD plots. Despite SWC, isotopic characteristics xylem similar ND, LD, Although transpiration plots was reduced compared plot, main depths proportions change. P. able shift source process wetting drying. healthy WUE_i more sensitive SWC. Our study shows although alleviate exhaustion reservoirs some extent, sustainable development afforestation ecosystems requires appropriate stand management measures maintain balanced forest-water relationships.