In the Netherlands, wetlands like bogs and marshes have significantly diminished over time. However, research by Renske Vroom, who will defend her doctoral thesis at Radboud University on September 13, indicates that these vital ecosystems can be restored through rewetting and planting the appropriate vegetation.
Wetlands, which include areas such as lowlands and marshes, are crucial for several reasons. According to ecologist Renske Vroom, “Wetlands are essential for clean water, flood prevention, and biodiversity. They also play a key role in carbon storage, which is important for climate regulation. When these areas are drained, excess CO2 is released, and the soil tends to sink.”
The need for wetland restoration is underscored by the Nature Restoration Act. While about 21% of wetlands globally are degraded, the situation is more severe in the Netherlands, where 77% of wetlands have been compromised. Many peat bogs in the country have been drained for agricultural purposes.
Rewetting these drained wetlands poses new challenges. Due to past intensive agriculture, these areas are often contaminated with harmful substances from fertilizers. Vroom explains, “Rewetting these areas can lead to the release of these substances back into the environment, which can negatively impact water quality.”
One solution is to cultivate plants on the rehydrated soil, as they absorb the nutrients and help improve the environment. In experiments conducted near Zaandam and in Germany, Vroom tested the effects of flooding various areas. Some areas were kept relatively dry, while others had water levels of up to 20 centimeters.
The research revealed that different plants thrive under different conditions. “Cattails perform well in nitrogen-rich peat, while Azolla, a type of duckweed, thrives in phosphate-rich environments. Peat moss is effective in nutrient-poor soils,” Vroom noted.
These plants have practical applications. For example, cattail can be used for insulation material and as cow feed, while Azolla can be used as animal feed or a soil enhancer.
This approach offers a dual benefit: it supports both environmental restoration and agricultural interests. Farmers can potentially rewet their land, cultivate useful plants, and sell the harvest.
Vroom emphasizes the importance of taking action. “While more research is often recommended, current studies show that these methods are effective. The key is to begin restoring wetlands. With rewetting and proper plant cultivation, the problem can be addressed,” she concludes.