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New Phytol. 2016 May;210(3):839-49. doi: 10.1111/nph.13868. Epub 2016 Feb 10.

High-resolution isotope measurements resolve rapid ecohydrological dynamics at the soil-plant interface.

Author information

1
Chair of Hydrology, Faculty of Environment and Natural Resources, University of Freiburg, Fahnenbergplatz, Freiburg, 79098, Germany.
2
Institute for Landscape Biogeochemistry, Leibniz Centre for Agricultural Landscape Research (ZALF), Eberswalder Strasse 84, Muencheberg, 15374, Germany.
3
Long-term Forest Ecosystem Research, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Zuercherstrasse 111, Birmensdorf, 8903, Switzerland.
4
Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Altensteinstrasse 6, Berlin, 14195, Germany.

Abstract

Plants rely primarily on rainfall infiltrating their root zones - a supply that is inherently variable, and fluctuations are predicted to increase on most of the Earth's surface. Yet, interrelationships between water availability and plant use on short timescales are difficult to quantify and remain poorly understood. To overcome previous methodological limitations, we coupled high-resolution in situ observations of stable isotopes in soil and transpiration water. We applied the approach along with Bayesian mixing modeling to track the fate of (2) H-labeled rain pulses following drought through soil and plants of deciduous tree ecosystems. We resolve how rainwater infiltrates the root zones in a nonequilibrium process and show that tree species differ in their ability to quickly acquire the newly available source. Sessile oak (Quercus petraea) adjusted root uptake to vertical water availability patterns under drought, but readjustment toward the rewetted topsoil was delayed. By contrast, European beech (Fagus sylvatica) readily utilized water from all soil depths independent of water depletion, enabling faster uptake of rainwater. Our results demonstrate that species-specific plasticity and responses to water supply fluctuations on short timescales can now be identified and must be considered to predict vegetation functional dynamics and water cycling under current and future climatic conditions.

KEYWORDS:

climate change; deciduous trees; ecohydrology; laser spectroscopy; plant-water relations; root uptake; soil water; stable isotopes

PMID:
26864434
DOI:
10.1111/nph.13868
[Indexed for MEDLINE]
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