Preprints
https://doi.org/10.5194/egusphere-2022-580
https://doi.org/10.5194/egusphere-2022-580
 
08 Jul 2022
08 Jul 2022

What determines peat swamp vegetation type in the Central Congo Basin?

Selena Georgiou1, Edward T. A. Mitchard1, Bart Crezee2, Paul I. Palmer1,3, Greta C. Dargie2, Sofie Sjögersten4, Corneille E. N. Ewango5,6, Ovide B. Emba7, Joseph T. Kanyama5, Pierre Bola7, Jean-Bosco N. Ndjango6, Nicholas T. Girkin8, Yannick E. Bocko9, Suspense A. Ifo10, and Simon L. Lewis2,11 Selena Georgiou et al.
  • 1School of GeoSciences, University of Edinburgh, Edinburgh, UK
  • 2School of Geography, University of Leeds, Leeds, UK
  • 3National Centre of Earth Observation (NCEO), University of Edinburgh, Edinburgh, UK
  • 4Faculty of Science, University of Nottingham, Nottingham, UK
  • 5Faculté de Gestion des Ressources Naturelles Renouvelables, Université de Kisangani, Kisangani, DRC
  • 6Faculté des Sciences, Université de Kisangani, Kisangani, DRC
  • 7Institut Supérieur Pédagogique de Mbandaka, Mbandaka, DRC
  • 8School of Water, Energy and Environment, Cranfield University, Cranfield, UK
  • 9Laboratoire de Botanique et Ecologie, Faculté des Sciences et Techniques, Université Marien Ngouabi, Brazzaville, RoC
  • 10École Normale Supérieure, Département des Sciences et Vie de la Terre, Laboratoire de Télédétection et d’Écologie Forestière, Université Marien Ngouabi, Brazzaville, RoC
  • 11Department of Geography, University College London, London, UK

Abstract. The Central Congo Basin is home to the largest peat swamp in the tropics. Two major vegetation types overlay the peat: hardwood trees, and palms (mostly the trunkless Raphia laurentii variety), with each dominant in different locations. The cause of the location of these differently composed swamp areas is not understood. We investigated their distribution using a recent vegetation classification across the 165,600 km2 region. Using a regression model we assessed the impacts of elevation, seasonal rainfall and temperature on the presence of each peat vegetation type. We used monthly 0.05° resolution CHIRPS rainfall climatology (CHPclim) and maximum temperature (CHIRTS) data together with 90 m resolution terrain data (MERIT Hydro). Our model was successful in predicting the percentage palm swamp composition when tested using data held back for verification, with R2 ~ 0.79, RMSE = 14.8 %, and p < 0.05 for the largely rain-fed hydrological sub-basins. However, it did not perform well in areas where peatland inundation is controlled by river flooding. We found that palm swamp composition varies primarily with elevation and dry season climatological variables (rainfall and temperature), with additional, significant contributions from the total wet season rainfall and temperature. There are indications of an optimal range of net water availability (the difference between rainfall and actual evapotranspiration, accounting for run-off) for palm swamp dominance, above and below which hardwood swamp dominates. In this study we progress our understanding of the determinants of peat swamp vegetation type in the central Congo Basin. Improved understanding will contribute to assessing how changes in environmental factors, including land-use and climate change impacts, could impact swamp type distribution and carbon fluxes in the future.

Selena Georgiou et al.

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-580', Anonymous Referee #1, 06 Sep 2022
    • AC1: 'Reply on RC1', Selena Georgiou, 29 Sep 2022
  • RC2: 'Comment on egusphere-2022-580', Anonymous Referee #2, 14 Sep 2022
    • AC2: 'Reply on RC2', Selena Georgiou, 29 Sep 2022

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-580', Anonymous Referee #1, 06 Sep 2022
    • AC1: 'Reply on RC1', Selena Georgiou, 29 Sep 2022
  • RC2: 'Comment on egusphere-2022-580', Anonymous Referee #2, 14 Sep 2022
    • AC2: 'Reply on RC2', Selena Georgiou, 29 Sep 2022

Selena Georgiou et al.

Selena Georgiou et al.

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Short summary
Two major vegetation types, hardwood trees and palms, overlay the Central Congo Basin peatland complex, each dominant in different locations. We investigated the influence of terrain and climatological variables on their distribution, using a regression model, and found elevation and seasonal rainfall and temperature contribute significantly. There are indications of an optimal range of net water input for palm swamp to dominate, above and below which hardwood swamp dominates.