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Evapotranspiration from a drained tropical peatland undergoing restoration
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  • Sarah Treby,
  • Charuni Jayasekara,
  • Nafila Idrus,
  • Sopa Nindia Ati Ningsih,
  • Laura L. B. Graham,
  • Lindsay Hutley,
  • Jason Beringer,
  • Samantha Grover
Sarah Treby
RMIT University Department of Applied Chemistry and Environmental Science

Corresponding Author:[email protected]

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Charuni Jayasekara
RMIT University Department of Applied Chemistry and Environmental Science
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Nafila Idrus
Borneo Orangutan Survival Foundation
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Sopa Nindia Ati Ningsih
Borneo Orangutan Survival Foundation
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Laura L. B. Graham
Borneo Orangutan Survival Foundation
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Lindsay Hutley
Charles Darwin University Research Institute for the Environment and Livelihoods
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Jason Beringer
The University of Western Australia School of Agricultural and Environment
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Samantha Grover
RMIT University Department of Applied Chemistry and Environmental Science
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Abstract

Tropical peatlands play a critical role in regional water cycling, yet most tropical peat swamp forests (PSFs) are anthropogenically disturbed though modification of the water table (e.g. drainage), deforestation, and fire events. These disturbances can alter ecosystem processes including evapotranspiration (ET), thereby creating feedbacks that degrade peatland ecosystem services and result in significant alteration of greenhouse gas budgets. However, our understanding of fine-scale hydrological fluxes in tropical peatland ecosystems is currently lacking. Here, therefore, we aimed to quantify rates of ET from a degraded tropical PSF in Central Kalimantan, in the context of broader peatland hydrology and site meteorology. From March to November 2020, ET ranged from 1.8–7.3 mm d -1, averaged 4.09 ± 0.06 mm d -1 and was consistent between months, despite large fluctuations in precipitation (P) following typical wet/dry seasonality (e.g., 4.1 ± 0.2 mm d -1 in July, compared to 17.5 ± 4.4 mm d -1 in April). Total ET over the nine-month study period was 1127 mm; approximately 37% of total precipitation. Daily ET rates were comparable to previous studies from tropical PSFs, however, the ratio of ET/P was lower than other tropical PSF sites. We suggest that the volume of water lost through canal drainage may be higher at this site than other tropical PSFs, indicating more substantial hydrological alteration through drainage. We expect that with continued hydrological restoration (i.e. canal blocking), ET/P may increase and, if so, could potentially be used as an indicator for changing peatland condition over time.