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Water‐isotope ecohydrology of Mount Kilimanjaro

Samuel Bodé (UGent) , Lien De Wispelaere (UGent) , Andreas Hemp, Dirk Verschuren (UGent) and Pascal Boeckx (UGent)
(2020) ECOHYDROLOGY. 13(1).
Author
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Abstract
Notwithstanding its crucial importance for assessing the vulnerability of tropical mountain ecosystems to both local anthropogenic pressure and climate change, knowledge of the relationships between climate, hydrology, and vegetation on Mount Kilimanjaro is highly fragmentary. Unraveling the pathway of water from precipitation to transpiration can also help validate paleoclimate proxies derived from the hydrogen- and oxygen-isotopic signatures of plant compounds, such as leaf waxes. We measured delta H-2 and delta O-18 in precipitation, stream, and soil water, and in xylem and leaf water of locally common plants, for four successive seasons along a 3,000-m altitudinal transect covering lowland savannah, lower and upper montane forest, and the subalpine zone on Mount Kilimanjaro. Across all four bioclimatic zones, delta H-2 and delta O-18 in precipitation decreased with monthly precipitation amount at a rate of -8 +/- 2 parts per thousand and -1.0 +/- 0.3 parts per thousand per 100 mm, respectively. Our xylem-water isotope data indicate that plants in general took up topsoil water during the northeasterly monsoon season and short dry season and gradually shifted to deeper soil water during the southeasterly monsoon season and the main dry season. Savannah trees and shrubs tapped from a water pool recharged by source water with a relatively constant isotopic signature. This observation conforms to the "two water worlds" hypothesis and implies a possible seasonal bias in plant-derived paleohydrological proxies. Finally, our results show strong correlation between xylem-to-leaf water-isotopic enrichment and ambient relative humidity, despite a bias in the savannah that we attribute to a leaf-cooling mechanism in this warm, semi-arid environment.
Keywords
East Africa, hydrogen-isotope fractionation, isotope paleorecords, Mount Kilimanjaro, paleohydrological proxy, precipitation, water-isotope ecohydrology, SOIL-WATER, HYDROGEN ISOTOPES, DEUTERIUM EXCESS, STABLE-ISOTOPES, SOUTHERN SLOPES, MT. KILIMANJARO, TROPICAL FOREST, CLIMATE-CHANGE, RAIN-FOREST, LEAF WATER

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Citation

Please use this url to cite or link to this publication:

MLA
Bodé, Samuel, et al. “Water‐isotope Ecohydrology of Mount Kilimanjaro.” ECOHYDROLOGY, vol. 13, no. 1, 2020, doi:10.1002/eco.2171.
APA
Bodé, S., De Wispelaere, L., Hemp, A., Verschuren, D., & Boeckx, P. (2020). Water‐isotope ecohydrology of Mount Kilimanjaro. ECOHYDROLOGY, 13(1). https://doi.org/10.1002/eco.2171
Chicago author-date
Bodé, Samuel, Lien De Wispelaere, Andreas Hemp, Dirk Verschuren, and Pascal Boeckx. 2020. “Water‐isotope Ecohydrology of Mount Kilimanjaro.” ECOHYDROLOGY 13 (1). https://doi.org/10.1002/eco.2171.
Chicago author-date (all authors)
Bodé, Samuel, Lien De Wispelaere, Andreas Hemp, Dirk Verschuren, and Pascal Boeckx. 2020. “Water‐isotope Ecohydrology of Mount Kilimanjaro.” ECOHYDROLOGY 13 (1). doi:10.1002/eco.2171.
Vancouver
1.
Bodé S, De Wispelaere L, Hemp A, Verschuren D, Boeckx P. Water‐isotope ecohydrology of Mount Kilimanjaro. ECOHYDROLOGY. 2020;13(1).
IEEE
[1]
S. Bodé, L. De Wispelaere, A. Hemp, D. Verschuren, and P. Boeckx, “Water‐isotope ecohydrology of Mount Kilimanjaro,” ECOHYDROLOGY, vol. 13, no. 1, 2020.
@article{8644083,
  abstract     = {{Notwithstanding its crucial importance for assessing the vulnerability of tropical mountain ecosystems to both local anthropogenic pressure and climate change, knowledge of the relationships between climate, hydrology, and vegetation on Mount Kilimanjaro is highly fragmentary. Unraveling the pathway of water from precipitation to transpiration can also help validate paleoclimate proxies derived from the hydrogen- and oxygen-isotopic signatures of plant compounds, such as leaf waxes. We measured delta H-2 and delta O-18 in precipitation, stream, and soil water, and in xylem and leaf water of locally common plants, for four successive seasons along a 3,000-m altitudinal transect covering lowland savannah, lower and upper montane forest, and the subalpine zone on Mount Kilimanjaro. Across all four bioclimatic zones, delta H-2 and delta O-18 in precipitation decreased with monthly precipitation amount at a rate of -8 +/- 2 parts per thousand and -1.0 +/- 0.3 parts per thousand per 100 mm, respectively. Our xylem-water isotope data indicate that plants in general took up topsoil water during the northeasterly monsoon season and short dry season and gradually shifted to deeper soil water during the southeasterly monsoon season and the main dry season. Savannah trees and shrubs tapped from a water pool recharged by source water with a relatively constant isotopic signature. This observation conforms to the "two water worlds" hypothesis and implies a possible seasonal bias in plant-derived paleohydrological proxies. Finally, our results show strong correlation between xylem-to-leaf water-isotopic enrichment and ambient relative humidity, despite a bias in the savannah that we attribute to a leaf-cooling mechanism in this warm, semi-arid environment.}},
  articleno    = {{e2171}},
  author       = {{Bodé, Samuel and De Wispelaere, Lien and Hemp, Andreas and Verschuren, Dirk and Boeckx, Pascal}},
  issn         = {{1936-0584}},
  journal      = {{ECOHYDROLOGY}},
  keywords     = {{East Africa,hydrogen-isotope fractionation,isotope paleorecords,Mount Kilimanjaro,paleohydrological proxy,precipitation,water-isotope ecohydrology,SOIL-WATER,HYDROGEN ISOTOPES,DEUTERIUM EXCESS,STABLE-ISOTOPES,SOUTHERN SLOPES,MT. KILIMANJARO,TROPICAL FOREST,CLIMATE-CHANGE,RAIN-FOREST,LEAF WATER}},
  language     = {{eng}},
  number       = {{1}},
  pages        = {{19}},
  title        = {{Water‐isotope ecohydrology of Mount Kilimanjaro}},
  url          = {{http://doi.org/10.1002/eco.2171}},
  volume       = {{13}},
  year         = {{2020}},
}

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