Paludiculture maintains peat formation potential in rewetted temperate fens

Abstract Drainage for agriculture has transformed temperate fen peatlands from carbon sinks into major carbon sources. Rewetting can halt this degradation, and the productive use of rewetted peatlands through paludiculture offers a promising sustainable land use strategy. However, historical drainage increases nutrient availability, which often remains elevated after rewetting. It is unknown how such nutrient conditions affect the potential of rewetted peatlands to form new peat, particularly under paludiculture use. We studied rewetted fens across temperate Europe with varying land uses (no use, low- and high-intensity paludiculture) and nutrient availability (low in Carex -dominated sites, high in Typha -dominated sites and quantified by Ellenberg Indicator Values). Over 2 years, we measured belowground biomass production using root ingrowth cores and decomposition using litterbags and calculated the peat formation potential as the standardized balance between these two processes. We hypothesized that paludiculture does not reduce peat formation potential compared to no agricultural land use after rewetting, that nutrient enrichment affects both production and decomposition equally, and that water availability and nutrient levels are key drivers of these processes. Paludiculture did not negatively affect peat formation potential in rewetted fens compared to non-used sites. Unexpectedly, belowground biomass production was higher in low-nutrient Carex -dominated sites than in high-nutrient Typha -dominated sites, while decomposition rates showed little difference across vegetation types and were lowest below moderate nutrient availability. Peat formation potential increased with a longer growing season, high water levels, and low nutrient availability. This is the first field-based study to quantify the balance of production and decomposition under different management and nutrient regimes in rewetted fens. The findings support the use of paludiculture on degraded, nutrient-rich fens to reduce nutrient loads and steering them to high peat formation potential, offering a sustainable solution for peatland restoration and agricultural land use.