Contrasting water sources used by a coniferous forest in the high-altitude, southeastern Tibetan Plateau

Forest trees use various water sources to adapt to environmental conditions in mountainous regions. However, water resources variances along elevational gradients are not clearly understood. This limits the assessment of the ecosystem responses to climate change. In this study, stable oxygen and hyd...

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Bibliographic Details
Published in:The Science of the total environment 2022-11, Vol.849, p.157913-157913, Article 157913
Main Authors: Xiangyang, Sun, Genxu, Wang, Juying, Sun, Shouqin, Sun, Zhaoyong, Hu, Chunlin, Song, Shan, Lin
Format: Article
Language:English
Subjects:
Stable isotopes
Subalpine
Tibetan Plateau
Water use
Winter precipitation
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Summary:Forest trees use various water sources to adapt to environmental conditions in mountainous regions. However, water resources variances along elevational gradients are not clearly understood. This limits the assessment of the ecosystem responses to climate change. In this study, stable oxygen and hydrogen isotopes were used to investigate the spatiotemporal patterns of water sources for Faber's fir in a humid high-altitude elevational gradient (ranging between 2800 m.a.s.l. and 3700 m.a.s.l.) on the southeastern Tibetan Plateau. The results indicated that 27 ± 8.3 % of the xylem water was from previous winter snowmelt between May and June. In contrast, almost all xylem water was from current summer precipitation between July and October. Faber's fir at the lower elevation (2800 m.a.s.l.) primarily relied on water derived from winter precipitation during May and June. Yet, trees located near the tree line (3700 m.a.s.l.) were mostly dependent on current precipitation over the entire growing season. However, when statistically analyzing data from all seven different elevation gradients in this study, the contribution of winter precipitation to xylem water was not elevation dependent. Precipitation contributed to a large proportion (59.86 % ± 33.43 %) of xylem water between May and October. Meanwhile, no linear contribution ratio of precipitation to trees was identified in this high-altitude elevational gradient. The replenishment of soil water and the soil water storage determine the spatiotemporal patterns of water sources. Climate change has the possibility of reducing winter precipitation at high altitudes on the Tibetan Plateau. Thus, tree water use at different altitude gradients will play varied roles in influencing the evolution of forest composition under ongoing climate change. 1. Forest water uptake has spatial-temporal patterns along an elevation gradient. 2. A. fabri used winter precipitation at the early growing season. 3. There were no statistical differences of water sources in steep mountains. [Display omitted] •Forest water uptake has spatial-temporal patterns along an elevation gradient.•A. fabri used winter precipitation at the early growing season.•There were no statistical differences of water sources in steep mountains.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2022.157913