Biorefinery potential of paludiculture biomass: composition and fractionation analysis of Phragmites, Phalaris, and Carex

Peatlands store vast global carbon reserves but drainage for agriculture has turned them into major CO 2 sources. Full rewetting without alternative production systems would threaten farm incomes and regional value chains. Markets and value chains for biomass from rewetted peatlands are still largely undeveloped, and detailed knowledge of its chemical composition and suitability for integration into existing processing industries is lacking. In this study, we systematically investigated three dominant wetland taxa, Phragmites australis , Phalaris arundinacea , and Carex spp., alongside Miscanthus × giganteus as a benchmark, focusing on their lignocellulosic characterization, lignin structure, and the performance in OrganoCat fractionation. This study aims to provide a detailed compositional characterization of peatland grasses to establish their biomass potential for applications of bio-based value chains. The peatland grasses showed lower cellulose (25%–32% vs. 42%) and in case of Carex and Phalaris also lower lignin contents (18% vs. 24%) compared to Miscanthus . The hemicellulose profiles of Miscanthus and Phragmites were dominated by xylose and arabinose, whereas Carex and Phalaris exhibited more complex mixtures indicative of more highly substituted arabinoxylans or multiple polysaccharide classes. Lignin architecture also varied: lignin–carbohydrate complex (LCC) densities were up to 25% higher in peatland grasses compared to Miscanthus . Phalaris showed more condensed G-rich lignins (20% higher than in Miscanthus ) and all peatland grasses showed a reduced S/G-ratio. Carex showed a higher ferulate content contrasting Miscanthus’ less cross-linked structure. It was also demonstrated that the composition of lignin-bound polysaccharides varies substantially among the investigated grasses. Fractionation of the biomasses equilibrated the species-specific diversity of the four grasses, yielding cellulose-rich pulps with comparable composition (55%–65% cellulose) and saccharification efficiencies (>75%). This homogeneity across the processed pulps enables flexible mixed-species peatland biorefineries within multifunctional paludiculture systems prioritizing peat conservation and greenhouse gas mitigation.