Abstract:

Rewetting drained peatlands and restoring their hydrological conditions can contribute to climate mitigation by reducing soil greenhouse gas emissions. However, re-establishment of degraded peatlands can pose a risk of phosphorus (P) mobilization due to anaerobic conditions that develop with rewetting. Harvesting plant biomass which removes nutrients accumulated in vegetation, has been proposed as a mitigation measure to address this risk. However, the time required to deplete P soil pools remains poorly understood. To address this knowledge gap, we investigated the impact of biomass harvesting in Kvorning, Denmark, scheduled for rewetting in 2025. We aimed to quantify P removal through biomass harvesting and assess how it changed over time since harvesting began in 2018. We examined whether changes in the plant community reflected P limitation following biomass harvesting and promoted improvements in vegetation diversity and habitat quality. Results showed that biomass harvesting removed considerable amounts of nutrients. However, removal rates did not decline over time, indicating no evidence of soil P depletion over the six-year study period. Moreover, nutrient removal rates were higher in Wet areas (78.6 kg N and 7.9 kg P/ha/year) than in Drier ones (62.0 kg N and 6.1 kg P/ha/year). Although species composition and community-level traits shifted following harvesting, there was no change in overall plant community structure. Our findings suggest that biomass harvesting can be an effective long-term strategy to mitigate nutrient release, though unlikely to deplete soil P rapidly without complementary interventions.

https://doi.org/10.1016/j.jenvman.2025.127974