Deuterium labelling of roots provides evidence of deep water access and hydraulic lift by Pinus nigra in a Mediterranean forest of NE Spain |
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| Affiliation: | 1. Department of Forest Ecology, Slovenian Forestry Institute, Večna pot 2, 1000 Ljubljana, Slovenia;2. Biotechnical Faculty, Department of Agronomy, University of Ljubljana, Jamnikarjeva 101, 1000 Ljubljana, Slovenia;3. Higher Vocational College for Forestry and Hunting, Ljubljanska cesta 2, 6230 Postojna, Slovenia;4. Department of Forest and Landscape Planning and Monitoring, Slovenian Forestry Institute, Večna pot 2, 1000 Ljubljana, Slovenia;1. State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China, School of Water Resources and Hydropower, Xi''an University of Technology, Xi''an 710048, China;2. Institute for Energy, Environment and Sustainable Communities, University of Regina, Regina, Saskatchewan S4S 0A2, Canada;3. State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing 100038, China;4. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.;5. Environmental Change Institute, University of Oxford, Oxford OX1 3QY, UK |
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| Abstract: | We studied the tree access to deep water sources and the possibility of hydraulic lift from the deep roots of a Pinus nigra tree to the shallow soil layers in a Mediterranean forest of NE Spain. We also studied the use of hydraulically lifted water by neighboring trees, shrubs, and sprouts. We enriched the roots of a large P. nigra (10 m tall) with deuterium by accessing them from a below ground cave. During the next 3 days we measured stable deuterium isotopic composition of xylem sap, shoot predawn and midday water potentials, and the leaf δ13C and δ15N of the P. nigra tree, neighboring Quercus ilex ballota trees and sprouts, and Juniperus oxycedrus shrubs. The study was conducted both in dry summer and in wet spring. In summer, deuterated water absorbed by deep roots of P. nigra appeared in the stem water of neighboring plants and in surface soil. The most δD-enriched plant xylem sap was found in the enriched P. nigra tree, followed by the Q. ilex sprouts, the small Q. ilex trees and the surface soil (15 cm). All these trends disappeared in the wet spring season, when HDO only slightly appeared in the surface soil. The results show that the studied P. nigra tree accesses deep water source and conducts hydraulic lift in this Mediterranean forest in dry summer but not necessarily in wet spring. |
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