Carbon cycling in different fen paludicultures - Short and long-term stability of sequestered C under different future groundwater level scenarios (CaCyPal)
In 2022, organic soils accounted for around 7.1% of total national emissions in Germany. Paludiculture, the agricultural or forestry use of rewetted peatlands, is considered one of the most promising measures for reducing greenhouse gas (GHG) emissions from organic soils. Recent studies indicate high CO2-C sequestration rates, with an average uptake of about 13.0 t CO2-eq ha-1 a-1 in properly managed paludicultures. The conversion of drained arable land into fen paludicultures could thus achieve a reduction potential of up to 53.4 t CO2-eq ha-1 a-1 and make paludicultures one of the most effective nature-based solutions in climate protection. However, the long-term stability of the measured high CO2 uptake capacity remains unclear, as all previous GHG studies were carried out at sites where the plants were only established before the measurements began.
The limited knowledge about the long-term effects of rewetting and paludiculture on GHG reduction currently makes it difficult to include them in national inventories, thus hindering mitigation measures and policy decisions. In addition to reducing emissions, the resilience of paludiculture to the impacts of climate change, especially droughts, must be ensured. Therefore, there is an urgent need for long-term studies and a deeper understanding of the C cycle and C sequestration mechanisms for a wide range of paludicultures.
Objectives
The aim of this project is to determine the fate of newly assimilated atmospheric CO2-C in different C pools. In addition, the stability and potential risk of remobilization of recently stored C under continuously wet conditions compared to climate change induced drought will be assessed for three paludiculture species (Carex acutiformis, Phalaris arundinacea, Typha latifolia). Under field conditions, plant CO2 uptake, C transfer and C metabolism in the plant-soil-atmosphere continuum will be quantified over different time periods.
In the 2026 vegetation period, the three paludiculture species will be marked with 13C-enriched CO2 one to nine times for short periods. In addition, the long-term GHG mitigation potential of the three paludiculture species will be quantified and the effects of a climate change-induced dry period will be investigated. All field experiments will be conducted at a fully equipped experimental site of the Peatland Science Center (PSC) of the Weihenstephan-Triesdorf University of Applied Sciences (HSWT). For high-frequency and precise GHG and δ13C measurements in CO2 and CH4, a novel, fully automated, hood-based GHG measurement system is used. In addition to GHG and isotope measurements, samples of plants, DOC, dissolved CO2 and CH4, SOC, Cmic and biochemical fractions of biomass and soil are analyzed for δ13C isotope signatures.
