Search Results (5)

The conversion of cultivated fen peat soils into rewetted soils can mitigate global climate change. Specifically, carbon in newly formed peat can store atmospheric CO₂ for a long time in soil, but alterations in the quality of soil organic matter are not well known. To shed light on the complex processes of peat degradation or new formation under dry or rewetting conditions, we investigated and quantified saturated n-alkyl acids as an indicator compound class of peatlands response to the contrasting management practices. The concentrations of saturated n-alkyl acids from two soil layers of the drained and rewetted were determined in two soil layers of drained and rewetted fenland types such as Alder Carr forest, coastal peatland, and percolation mire. The analytical methods were solvent extraction, methylation with tetramethylammonium hydroxide, and gas chromatography/mass spectrometry. The saturated n-alkyl acid distribution pattern showed that the concentrations of long C-chain lengths were larger by factors of up to 28 relative to the short C-chain lengths. The effect of rewetting was reflected by the ratios of the summed concentrations of long (n-C_21:0 to n-C_34:0) to short (n-C_10:0 to n-C_20:0) C-chain saturated n-alkyl acids for drained and rewetted peat soil samples. These ratios were consistently lower in samples from the rewetted sites, indicating a higher input of microbial bio- and necromass to soil organic matter, likely from algae and anaerobic bacteria, under rewetting. The results suggest that the enrichment of microbial biomass and necromass in rewetted soils may be an important contributor to the formation of new peat in fenlands, irrespective of fenland type. Full article

Storm runoff in basins is comprised of various runoff processes with widely disparate infiltration and storage capacities, such as Hortonian overland flow (HOF), saturated overland flow (SOF), sub-surface flow (SSF), and deep percolation (DP). Areas may be classified according to these various runoff processes based on the soil characteristics, geology, topography, and land-use. This study analyzes changes in runoff components in the Jialu River basin and the Fen River (Jingle sub-basin) during runoff generation from 1980 to 2013 using the runoff segmentation method. Based on the decision scheme, the dominant runoff process (DRP) in the basins was distinguished using geographic information system (GIS) tools. The impact of different runoff process distributions on the changes in the runoff for the basin was determined. The results show that the floods in the Jialu River basin and Jingle sub-basin were dominated by overland flow components. Compared with 1980–1999, the proportion of overland flow components for 2000–2013 in two basins showed a decreasing trend by 8.3% and 7.1%, respectively, while the interflow and underground runoff components increased. In addition, HOF was the DRP in the Jialu River basin and Jingle sub-basin from 2000 to 2013. The area of the rapid runoff processes (HOF, SOF1, and SSF1) in the Jialu River basin and Jingle sub-basin accounted for 89% and 78% of the entire basin, respectively. In contrast, the slow runoff processes (SOF2, SSF2, and DP) accounted for 11% and 22% of the entire basin, respectively. The runoff of the Jingle sub-basin was substantially lower than that of the Jialu River basin under the same rainfall conditions, because of the influence of the distribution of different runoff processes. Compared with the Jialu River Basin, the peak discharge and runoff of Jingle sub-basin were 190.4 m³/s and 2.85 mm lower on average, respectively. The results of this study provide useful information to understand land-use changes and formulate management practices to reduce flooding in the Yellow River. Full article

Drained peatlands are important sources of greenhouse gases and are rewetted to curb these emissions. We study one drained and one rewetted fen in terms of losses—and, after rewetting—gains of organic matter (OM), carbon (C), and peat thickness. We determined bulk density (BD) and ash/OM (and C/OM) ratios for 0.5 cm thick contiguous slices from peat monoliths to calculate losses. Whereas one site has lost 28.5 kg OM m⁻² corresponding to annual emissions of ~10 t CO₂ ha⁻¹ a⁻¹ over 50 years of effective drainage, the other site has lost 102 kg OM m⁻², corresponding to an annual loss of ~30 t CO₂ ha⁻¹ a⁻¹ for 30 years of intensive drainage and 6 t CO₂ ha⁻¹ a⁻¹ during ~225 years of weak drainage before that. Height losses ranged from 43 to 162 cm. In the 20 years after rewetting, 2.12 kg C m⁻² was accumulated, equaling an average annual uptake of ~0.4 kg CO₂ m⁻² a⁻¹. The results indicate that rewetting can lead to carbon accumulation in fens. This sink function is only small compared with the high emissions that are avoided through rewetting. Full article

Of all terrestrial ecosystems, peatlands store carbon most effectively in long-term scales of millennia. However, many peatlands have been drained for peat extraction or agricultural use. This converts peatlands from sinks to sources of carbon, causing approx. 5% of the anthropogenic greenhouse effect and additional negative effects on other ecosystem services. Rewetting peatlands can mitigate climate change and may be combined with management in the form of paludiculture. Rewetted peatlands, however, do not equal their pristine ancestors and their ecological functioning is not understood. This holds true especially for groundwater-fed fens. Their functioning results from manifold interactions and can only be understood following an integrative approach of many relevant fields of science, which we merge in the interdisciplinary project WETSCAPES. Here, we address interactions among water transport and chemistry, primary production, peat formation, matter transformation and transport, microbial community, and greenhouse gas exchange using state of the art methods. We record data on six study sites spread across three common fen types (Alder forest, percolation fen, and coastal fen), each in drained and rewetted states. First results revealed that indicators reflecting more long-term effects like vegetation and soil chemistry showed a stronger differentiation between drained and rewetted states than variables with a more immediate reaction to environmental change, like greenhouse gas (GHG) emissions. Variations in microbial community composition explained differences in soil chemical data as well as vegetation composition and GHG exchange. We show the importance of developing an integrative understanding of managed fen peatlands and their ecosystem functioning. Full article

We present analyses of macroscopic and microscopic remains as a tool to characterise sedge fen peats. We use it to describe peat composition and stages of peat decomposition, to assess the success of rewetting of a formerly drained fen, and to understand the workings of these novel ecosystems. We studied two percolation fen sites, one drained and one drained and rewetted 20 years ago. Years of deep drainage have resulted in a layer of strongly decomposed peat which lacks recognizable macro-remains. We could associate micro-remains with macro-remains, and thus still characterise the peat and the plants that once formed it. We show that the strongly decomposed peat is of the same origin as the slightly decomposed peat below, and that is was ploughed. We present descriptions of eight types of the main constituent of sedge peat: plant roots, including Carex rostrata type, C. lasiocarpa/rostrata type, C. limosa type, C. acutiformis type, C. echinata type, Phragmites australis type, Cladium type, Equisetum type. We describe three new non-pollen palynomorph types (microscopic remains) and five new subtypes. The rewetted fen provides insights into plant succession after rewetting and the formation of peat that predominantly consists of roots. Results indicate that leaf sheaths may be a consistent component of the peat. Full article