Influence of forest and shrub canopies on precipitation partitioning and isotopic signatures

Chris Soulsby, Hannah Braun, Matthias Sprenger, Markus Weiler, Doerthe Tetzlaff

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17 Citations (Scopus)
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Abstract

Over a four-month summer period, we monitored how forest (Pinus sylvestris) and heather moorland (Calluna spp. and Erica spp.) vegetation canopies altered the volume and isotopic composition of net precipitation (NP) in a southern boreal landscape in northern Scotland. During that summer period, interception (I) losses were relatively high, and higher under forests compared to moorland (46% of gross rainfall (GR) compared with 35%, respectively). Throughfall (TF) volumes exhibited marked spatial variability in forests, depending upon local canopy density, but were more evenly distributed under heather moorland. In the forest stands, stemflow (StF) was a relatively small canopy flow path accounting for only 0.9-1.6% of NP and only substantial in larger events. Overall, the isotopic composition of NP was not markedly affected by canopy interactions; temporal variation of stable water isotopes in TF closely corresponded to that of GR with differences of TF-GR being -0.52 ‰ for δ2 H and - 0.14 ‰ for δ18O for forests and 0.29 ‰ for δ2 H and -0.04 ‰ for δ18O for heather moorland. These differences were close to, or within, analytical precision of isotope determination, though the greater differences under forest were statistically significant. Evidence for evaporative fractionation was generally restricted to low rainfall volumes in low intensity events, though at times subtle effects of liquid-vapour moisture exchange and/or selective transmission though canopies were evident. Fractionation and other effects were more evident in StF but only marked in smaller events. The study confirmed earlier work that increased forest cover in the Scottish Highlands will likely cause an increase in interception and green water fluxes at the expenses of blue water fluxes to streams. However, the low energy, humid environment means that isotopic changes during such interactions will only have a minor overall effect on the isotopic composition of NP.
Original languageEnglish
Pages (from-to)4282-4296
Number of pages15
JournalHydrological Processes
Volume31
Issue number24
Early online date17 Oct 2017
DOIs
Publication statusPublished - 30 Nov 2017

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moorland
shrub
partitioning
canopy
throughfall
stemflow
rainfall
isotopic composition
interception
fractionation
isotope
humid environment
summer
forest cover
water
temporal variation
moisture
liquid
vegetation
energy

Keywords

  • Forest hydrology
  • interception
  • throughfall
  • isotopes
  • canopy
  • boreal forest

Cite this

Influence of forest and shrub canopies on precipitation partitioning and isotopic signatures. / Soulsby, Chris; Braun, Hannah; Sprenger, Matthias; Weiler, Markus; Tetzlaff, Doerthe.

In: Hydrological Processes, Vol. 31, No. 24, 30.11.2017, p. 4282-4296.

Research output: Contribution to journalArticle

Soulsby, Chris ; Braun, Hannah ; Sprenger, Matthias ; Weiler, Markus ; Tetzlaff, Doerthe. / Influence of forest and shrub canopies on precipitation partitioning and isotopic signatures. In: Hydrological Processes. 2017 ; Vol. 31, No. 24. pp. 4282-4296.
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abstract = "Over a four-month summer period, we monitored how forest (Pinus sylvestris) and heather moorland (Calluna spp. and Erica spp.) vegetation canopies altered the volume and isotopic composition of net precipitation (NP) in a southern boreal landscape in northern Scotland. During that summer period, interception (I) losses were relatively high, and higher under forests compared to moorland (46{\%} of gross rainfall (GR) compared with 35{\%}, respectively). Throughfall (TF) volumes exhibited marked spatial variability in forests, depending upon local canopy density, but were more evenly distributed under heather moorland. In the forest stands, stemflow (StF) was a relatively small canopy flow path accounting for only 0.9-1.6{\%} of NP and only substantial in larger events. Overall, the isotopic composition of NP was not markedly affected by canopy interactions; temporal variation of stable water isotopes in TF closely corresponded to that of GR with differences of TF-GR being -0.52 ‰ for δ2 H and - 0.14 ‰ for δ18O for forests and 0.29 ‰ for δ2 H and -0.04 ‰ for δ18O for heather moorland. These differences were close to, or within, analytical precision of isotope determination, though the greater differences under forest were statistically significant. Evidence for evaporative fractionation was generally restricted to low rainfall volumes in low intensity events, though at times subtle effects of liquid-vapour moisture exchange and/or selective transmission though canopies were evident. Fractionation and other effects were more evident in StF but only marked in smaller events. The study confirmed earlier work that increased forest cover in the Scottish Highlands will likely cause an increase in interception and green water fluxes at the expenses of blue water fluxes to streams. However, the low energy, humid environment means that isotopic changes during such interactions will only have a minor overall effect on the isotopic composition of NP.",
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AU - Soulsby, Chris

AU - Braun, Hannah

AU - Sprenger, Matthias

AU - Weiler, Markus

AU - Tetzlaff, Doerthe

N1 - We thank the European Research Council ERC (project GA 335910 VEWA) for funding the VeWa project and The Leverhulme Trust (project PLATO, RPG-2014-016) for funding.

PY - 2017/11/30

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N2 - Over a four-month summer period, we monitored how forest (Pinus sylvestris) and heather moorland (Calluna spp. and Erica spp.) vegetation canopies altered the volume and isotopic composition of net precipitation (NP) in a southern boreal landscape in northern Scotland. During that summer period, interception (I) losses were relatively high, and higher under forests compared to moorland (46% of gross rainfall (GR) compared with 35%, respectively). Throughfall (TF) volumes exhibited marked spatial variability in forests, depending upon local canopy density, but were more evenly distributed under heather moorland. In the forest stands, stemflow (StF) was a relatively small canopy flow path accounting for only 0.9-1.6% of NP and only substantial in larger events. Overall, the isotopic composition of NP was not markedly affected by canopy interactions; temporal variation of stable water isotopes in TF closely corresponded to that of GR with differences of TF-GR being -0.52 ‰ for δ2 H and - 0.14 ‰ for δ18O for forests and 0.29 ‰ for δ2 H and -0.04 ‰ for δ18O for heather moorland. These differences were close to, or within, analytical precision of isotope determination, though the greater differences under forest were statistically significant. Evidence for evaporative fractionation was generally restricted to low rainfall volumes in low intensity events, though at times subtle effects of liquid-vapour moisture exchange and/or selective transmission though canopies were evident. Fractionation and other effects were more evident in StF but only marked in smaller events. The study confirmed earlier work that increased forest cover in the Scottish Highlands will likely cause an increase in interception and green water fluxes at the expenses of blue water fluxes to streams. However, the low energy, humid environment means that isotopic changes during such interactions will only have a minor overall effect on the isotopic composition of NP.

AB - Over a four-month summer period, we monitored how forest (Pinus sylvestris) and heather moorland (Calluna spp. and Erica spp.) vegetation canopies altered the volume and isotopic composition of net precipitation (NP) in a southern boreal landscape in northern Scotland. During that summer period, interception (I) losses were relatively high, and higher under forests compared to moorland (46% of gross rainfall (GR) compared with 35%, respectively). Throughfall (TF) volumes exhibited marked spatial variability in forests, depending upon local canopy density, but were more evenly distributed under heather moorland. In the forest stands, stemflow (StF) was a relatively small canopy flow path accounting for only 0.9-1.6% of NP and only substantial in larger events. Overall, the isotopic composition of NP was not markedly affected by canopy interactions; temporal variation of stable water isotopes in TF closely corresponded to that of GR with differences of TF-GR being -0.52 ‰ for δ2 H and - 0.14 ‰ for δ18O for forests and 0.29 ‰ for δ2 H and -0.04 ‰ for δ18O for heather moorland. These differences were close to, or within, analytical precision of isotope determination, though the greater differences under forest were statistically significant. Evidence for evaporative fractionation was generally restricted to low rainfall volumes in low intensity events, though at times subtle effects of liquid-vapour moisture exchange and/or selective transmission though canopies were evident. Fractionation and other effects were more evident in StF but only marked in smaller events. The study confirmed earlier work that increased forest cover in the Scottish Highlands will likely cause an increase in interception and green water fluxes at the expenses of blue water fluxes to streams. However, the low energy, humid environment means that isotopic changes during such interactions will only have a minor overall effect on the isotopic composition of NP.

KW - Forest hydrology

KW - interception

KW - throughfall

KW - isotopes

KW - canopy

KW - boreal forest

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DO - 10.1002/hyp.11351

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EP - 4296

JO - Hydrological Processes

JF - Hydrological Processes

SN - 0885-6087

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ER -