| 1. |
- Andert, Janet, et al.
(författare)
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Temporal Changes in Methane Oxidizing and Denitrifying Communities and Their Activities in a Drained Peat Soil
- 2012
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Ingår i: Wetlands. - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 32, s. 1047-1055
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Tidskriftsartikel (refereegranskat)abstract
- Northern peat soils are both sources and sinks of the greenhouse gases nitrous oxide (N2O) and methane (CH4). These fluxes are regulated by the activity of microbial communities. Temporal, spatial and depth related differences in potential activity and composition of the denitrifier and methanotrophic bacterial communities were compared between winter and summer in relation to in situ fluxes of N2O and CH4 from a drained and forested peat land in Sweden. The composition of the genetic pool of these guilds was assessed using terminal fragment length polymorphism analysis of signature genes in the denitrification and methane oxidation pathways, respectively. The composition of the communities was similar throughout the soil profile, although both denitrification and methane oxidation rates decreased with soil depth. The potential methane oxidation rates were significantly correlated to soil N content, and , indicating a nitrogen induced stimulation of methane oxidation capacity. The site was a source of N2O and a small sink for CH4, and although the fluxes did not vary significantly over time, both the methane oxidizing and denitrifier community composition exhibited temporal patterns. Differences in the composition of the methanotrophic community reflected that the peat site shifted from a summer to a winter community. The denitrifiers exhibited a similar trend, but also differed significantly between the sampling occasions during summer, as well as between locations at the site. The latter was explained by differences in soil pH. It was only the differences in the methane oxidizer community composition that correlated with its corresponding potential activity, which implies a higher degree of functional redundancy within the denitrifier community.
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| 2. |
- Beltman, B., et al.
(författare)
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Phosphate Release Upon Long- and Short -Term Flooding of Fen Meadows Depends on Land Use History and Soil pH
- 2014
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Ingår i: Wetlands (Wilmington, N.C.). - : Springer Netherlands. - 0277-5212 .- 1943-6246. ; 34:5, s. 989-1001
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Tidskriftsartikel (refereegranskat)abstract
- Flooding of acidified and desiccated fen meadows is a management approach for mitigating loss of plant species as well as a short-term measure to prevent flooding in urban areas. Studies have shown that flooding events can cause extreme P release from soils. We questioned whether the occurrence of this 'internal eutrophication' from flooding depended on fertilization history and soil pH. A greenhouse experiment with soil cores from Ireland (turloughs) and from the Netherlands, exposed to flooding for 216 days (long-term) showed a substantial P release for sites with a history of fertilizer use only. Short-term flooding (20-25 days) caused little P release in all soils. There was no correlation between P release and initial soil pH (range 4.1-7.1). All flooded soils showed a significant decline in sulfate and increased iron in the pore water upon flooding. Field trials applying short term flooding to sites differing in soil pH, average soil moisture and history of fertilizer application showed there was no overall effect of flooding on phosphate, nitrate, ammonium, iron concentrations and pH of pore water. Sulfate concentrations significantlyincreased. Hence, problematic phosphate release is only induced by long term flooding of fen meadows with a history of fertilization.
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| 3. |
- Hedmark, Åsa
(författare)
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Carbon Storage and Fluxes within Freshwater Wetlands: a Critical Review
- 2010
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Ingår i: Wetlands. - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 30, s. 111-124
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Forskningsöversikt (refereegranskat)abstract
- We critically review recent literature on carbon storage and fluxes within natural and constructed freshwater wetlands, and specifically address concerns of readers working in applied science and engineering. Our purpose is to review and assess the distribution and conversion of carbon in the water environment, particularly within wetland systems. A key aim is to assess if wetlands are carbon sinks or sources. Carbon sequestration and fluxes in natural and constructed wetlands located around the world has been assessed. All facets of carbon (solid and gaseous forms) have been covered. We draw conclusions based on these studies. Findings indicate that wetlands can be both sources and sinks of carbon, depending on their age, operation, and the environmental boundary conditions such as location and climate. Suggestions for further research needs in the area of carbon storage in wetland sediments are outlined to facilitate the understanding of the processes of carbon storage and removal and also the factors that influence them.
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| 4. |
- Kardol, Paul
(författare)
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Modeling Carbon Fluxes Using multi-Temporal MODIS Imagery and CO2 Eddy Flux Tower Data in Zoige Alpine Wetland, South-West China
- 2014
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Ingår i: Wetlands. - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 34, s. 603-618
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Tidskriftsartikel (refereegranskat)abstract
- An accurate and synoptic quantification of gross primary production (GPP) in wetland ecosystems is essential for assessing carbon budgets at regional or global scales. In this study, a satellite-based Vegetation Photosynthesis Model (VPM) integrated with observed eddy tower and remote sensing data was employed and adapted to evaluate the feasibility and dependability of the model for estimating GPP in an alpine wetland, located in Zoige, Southwestern China. Eddy flux data from 2-year observations showed that temperature explained most of the seasonal variability in carbon fluxes and that warming increased GPP and ecosystem respiration, and hence affected the carbon balance of alpine wetlands. The comparison between modeled and observed GPP fluxes indicated that simulated values were largely in agreement with tower-based values (P < 0.0001). 12-year long-term simulations (2000-2011) found that (1) there was significantly increasing trends at rate of 17.01 gCm(-2) year(-1) for annual GPP (R (2) = 0.62, P = 0.002); (2) the inter-annual variation in GPP was highly sensitive to climate warming; and (3) a warmer climate can prolong the plant growing season and, by that, increase wetland productivity. Our results demonstrated that the satellite-driven VPM model has the potential to be applied at large spatial and temporal scales for scaling-up carbon fluxes of alpine wetlands.
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| 5. |
- Lehsten, Dörte, et al.
(författare)
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Simulation of Water Level Fluctuations in Kettle Holes Using a Time Series Model
- 2011
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Ingår i: Wetlands. - : Springer Science and Business Media LLC. - 0277-5212 .- 1943-6246. ; 31:3, s. 511-520
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Tidskriftsartikel (refereegranskat)abstract
- Kettle holes are widespread in moraine landscapes. Their hydrological properties may be very vulnerable to changes in climatic conditions. To increase our knowledge of how kettle holes function and how they may be affected by climate change requires a model that can be applied to a variety of them regardless of their properties. We used the PIRFICT time series model to simulate the water levels in kettle holes over the last 50 years. For model calibration we applied time series of two-year lengths. We observed correlations between climate indices and water level statistics with a delayed response of one year. The results show a decrease in autumn low water levels and an increase in water level fluctuations. These effects correspond to observed increased summer evaporation and winter precipitation, and imply that the habitat quality dynamic of kettle holes depends on climatic conditions. With the prognosis of even warmer and dryer summers in Europe in the future, conservation strategies for kettle holes should include the effects of climate change.
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