Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Discussion papers
https://doi.org/10.5194/bg-2016-297
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-2016-297
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Submitted as: research article 24 Aug 2016

Submitted as: research article | 24 Aug 2016

Review status
This discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The manuscript was not accepted for further review after discussion.

Rooting and plant density strongly determine greenhouse gas budget of water hyacinth (Eichhornia crassipes) mats

Ernandes Sobreira Oliveira Junior1, Yingying Tang1, Sanne J. P. van den Berg2, Leon P. M. Lamers1,3, and Sarian Kosten1 Ernandes Sobreira Oliveira Junior et al.
  • 1Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, the Netherlands
  • 2B‐WARE Research Centre, P.O. Box 6558, 6503 GB, Nijmegen, the Netherlands
  • 3Department of Aquatic Ecology and Water Quality Management, Wageningen University and Research Centre, P.O. Box 47, 6700 AA Wageningen, the Netherlands

Abstract. Water hyacinth occurs in numerous tropical and subtropical countries, either as a native or as an invasive exotic species, where it can establish large and dense mats. The plant is also frequently used for water purification and bioremediation purposes. Although it is a free-floating species, the plant roots into the sediment of shallow waters, tapping into the sediment nutrient pool. Its long and extensive root system strongly increases nutrient absorption, resulting in high growth rates and concurring high carbon sequestration rates. On the other hand, the plants may also fuel methane (CH4) production as dense mats may deplete oxygen in the surface water and sediment below, which in combination with the high production of organic matter creates favorable conditions for methanogenesis. We hypothesize that water hyacinth vegetation acts as a strong greenhouse gas (GHG) sink due to its high growth rates, especially when (sediment) nutrient availability is high. Still, this sink may be counterbalanced by CH4 release, which will be most pronounced when the plants are rooting in the sediment due to potential CH4 shuttling from the sediment through the roots and leaves into the atmosphere (chimney effect). To mechanistically unravel the influence of water hyacinth on nutrient dynamics and greenhouse gas fluxes, we performed an aquarium experiment in which plant density and root access to the sediment were manipulated. Although plant cover led to lower concentrations of dissolved total phosphorus (DTP) and phosphate, there were no effects of density or rooting. We found no vegetation effect on the ebullition of CH4, but its diffusion was 4.5 times higher at high plant coverage. Rooting increased CH4 diffusion by 1.3 (high density) and 4 times (low density), demonstrating the chimney effect that we hypothesized. Independent of rooting, however, water hyacinth at high density sequestrated less carbon compared to low density, possibly due to space limited growth and self-shading. Overall, water hyacinth enhanced CH4 emissions, especially when rooted. Due to water hyacinth's high CO2 sequestration rates, the overall GHG budget in terms of CO2 equivalents still resulted in water hyacinth mats being near-neutral or even a GHG sink, depending on water hyacinth density. Our results show that the effect of water hyacinth mats on GHG fluxes strongly depends on both plant density and contact with the sediment. This indicates that, when making regional GHG balances, not only plant presence but also its density and water depth – regulating sediment-root contact – should be taken into account.

Ernandes Sobreira Oliveira Junior et al.
Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Ernandes Sobreira Oliveira Junior et al.
Ernandes Sobreira Oliveira Junior et al.
Viewed  
Total article views: 617 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
458 128 31 617 53 2 35
  • HTML: 458
  • PDF: 128
  • XML: 31
  • Total: 617
  • Supplement: 53
  • BibTeX: 2
  • EndNote: 35
Views and downloads (calculated since 24 Aug 2016)
Cumulative views and downloads (calculated since 24 Aug 2016)
Viewed (geographical distribution)  
Total article views: 615 (including HTML, PDF, and XML) Thereof 611 with geography defined and 4 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
Latest update: 18 Sep 2019
Publications Copernicus
Download
Short summary
The differential effects of the aquatic plants on greenhouse gas fluxes may be due to plant density and whether or not the plant roots can access the sediment. We therefore looked into the effect of these two variables on water hyacinth greenhouse gas balance using a laboratory experiment. We found that greenhouse gas dynamics were strongly influenced by plant density and rooting. Our findings pinpoint management options that can optimize carbon sequestration and minimize CH4 emissions.
The differential effects of the aquatic plants on greenhouse gas fluxes may be due to plant...
Citation