Wetlands, such as bogs, fens and floodplains, provide clean water, protect against flooding and store carbon. However, wetlands have been extensively degraded by human intervention, such as reclamation or excavation. This leads to poor water quality, flooding and high greenhouse gas emissions. Wetlands therefore urgently need to be restored, for example by flooding drained areas again. In my PhD thesis, I investigated an innovative solution for wetland restoration while preserving agriculture: growing marsh plants after humidification.
The crops studied in this PhD thesis absorb many nutrients, thus improving water quality, preventing downstream loss of nutrients and extracting accumulated nutrients from the soil. The composition of surface water plays an important role here: nitrogen-rich irrigation water in cattail and reed crops can promote both plant growth and the withdrawal of other nutrients. The effect of marsh plants on greenhouse gas methane emissions is complex and depends on plant species, water levels and nutrient availability. Methane bubbles can contribute substantially to total emissions and should be included in emission measurements after rewetting. While there are important considerations to be made in the cultivation of wetland plants, humidifying wetlands and keeping them wet must be paramount to preserve and restore its essential functions.
Renske Vroom studied Biology (BSc) and Environmental Sciences (MSc) at Wageningen University. After graduating in 2016, she started as a junior researcher in the Department of Aquatic Ecology and Environmental Biology at Radboud University. Here she investigated nutrient fluxes and greenhouse gas exchange in paludiculture. In 2019, she started her PhD research into the possibilities to extract phosphate from humidified former agricultural land by growing the floating plant Azolla. In the same year, she received a Royal Netherlands Academy of Arts and Sciences (KNAW) Ecology Fund and went to Brazil to study greenhouse gas emissions from fish ponds. In 2022, she received a Christine Mohrmann scholarship for outstanding female PhD candidates. She is currently working as a postdoc researcher in the Department of Peatland Studies and Palaeoecology at the University of Greifswald.