Field evidence for buoyancy-driven water flow in a Sphagnum dominated peat bog

Denitrification is well known being the most important nitrate-consuming process in water-logged peat soils, whereby the intermediate compound nitrous oxide (N(2)O) and the end product dinitrogen (N(2)) are ultimately released. The present study was aimed at evaluating the release of these gases (due to denitrification) from a nutrient-poor transition bog ecosystem under drained and three differently rewetted conditions at the field scale using a (15)N-tracer approach ([(15)N]nitrate application, 30 kg N ha(-1)) and a common closed-chamber technique. The drained site is characterized by a constant water table (WT) of -30 cm (here referred to as D30), while rewetted sites represent a constant WT of -15 cm, a constant WT of 0 cm (i.e. waterlogged), and an initial WT of 0 cm (which decreased slightly during the experiment), respectively, (here referred to as R15, R0, and R0(d), respectively). The highest N(2)O emissions were observed at D30 (291 µg N(2)O-N m(-2) h(-1)) as well as at R0d (665 µg N(2)O-N m(-2) h(-1)). At the rewetted peat sites with a constant WT (i.e. R15 and R0), considerably lower N2O emissions were observed (maximal 37 µg N(2)O-N m(-2) h(-1)). Concerning N(2) only at the initially water-logged peat site R0d considerable release rates (up to 3110 µg N(2)-N m(-2) h(-1)) were observed, while under drained conditions (D30) no N(2) emission and under rewetted conditions with a constant WT (R15 and R0) significantly lower N(2) release rates (maximal 668 µg N(2)-N m(-2) h(-1)) could be detected. In addition, it has been found that natural WT fluctuations at rewetted peat sites, in particular a rapid drop down of the WT, can induce high emission rates for both N(2)O and N(2).

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“…This was reported by Rappoldt et al [95] and Adema et al [96] for a water-saturated moss-dominated peat soil layer (i.e. acrotelm).…”

Section: Loss Of Added No − 3 − N Due To Gaseous N Release To the Atmsupporting

confidence: 69%

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [¹⁵N]nitrate–bromide double-tracer study

Tauchnitz¹,

Spott

Russow

et al. 2015

Isotopes in Environmental and Health Studies

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“…The most likely explanation for this is that surface moisture content is subjected to short‐term (i.e. daily; Adema et al ., ) fluctuations that are difficult to capture in one‐off sampling methods (Sullivan and Booth, ). The meteorology of this region, in particular the high wind speeds, may have a strong influence on surface moisture conditions while having less effect on the water table position.…”

Section: Discussionmentioning

confidence: 99%

Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

Bellen

Mauquoy

Payne

et al. 2014

J Quaternary Science

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Testate amoebae are abundant and diverse in Sphagnum peat bogs and have been used extensively as indicators of past water table depths. Although these unicellular protists are widely dispersed with globally similar hydrological preferences, regional variations in communities demand region-specific transfer functions. Here we present the first transfer function for southern Patagonian bogs, based on 154 surface samples obtained from transects in five bogs sampled in 2012 and 2013. Significant variance was explained by pH, electrical conductivity and, in particular, water table depth. Transfer functions for water table were constructed using weighted averaging and evaluated by cross-validation and independent test sets. The optimal transfer function has predictive ability, but relatively high prediction errors given the wide range in sampled water tables. The use of independent test sets, as well as cross-validation, allows a more rigorous assessment of model performance than most previous studies. For a subset of locations we compare surface and subsurface samples to demonstrate significant differences in community composition, possibly due to vertical zonation. Our results provide the first quantification of hydrological optima and tolerances for several rare species, which may include Southern Hemisphere endemics and pave the way for palaeohydrological reconstructions in southern Patagonian bogs.

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“…With increasing distance from buffered conditions combined with the ability of peat mosses to retain rainwater, the influence of nutrient‐poor and less buffered rainwater increases, and acids produced are less easily neutralized (Bootsma et al, ; Granath et al, ; Soudzilovskaia et al, ; van Breemen, ). Nevertheless, we still found the highest bio‐available P concentration in poor fen vegetation in the upper soil layer, which may be explained by either the fact that sphagnum lacks roots able to mobilize this P fraction or by self‐facilitating feedbacks of poor fen species that cause a buoyancy‐driven upward flow of underlying water with an extra supply of nutrients (Adema et al, ; Rappoldt et al, ).…”

Section: Discussionmentioning

confidence: 84%

Self‐facilitation and negative species interactions could drive microscale vegetation mosaic in a floating fen

Bergen

Temmink

Tweel‐Groot

et al. 2020

J Vegetation Science

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Aim The formation of a local vegetation mosaic may be attributed to local variation in abiotic environmental conditions. Recent research, however, indicates that self‐facilitating organisms and negative species interactions may be a driving factor. In this study, we explore whether heterogeneous geohydrological conditions or vegetation feedbacks and interactions could be responsible for a vegetation mosaic of rich and poor fen species. Location Lake Aturtaun, Roundstone Bog, Ireland. Methods In a floating fen, transects were set out to analyze the relation between vegetation type and rock–peat distance and porewater electrical conductivity. Furthermore, three distinct vegetation types were studied: rich fen, poor fen and patches of poor fen within rich fen vegetation. Biogeochemical measurements were conducted in a vertical profile to distinguish abiotic conditions of distinct vegetation types. Results Geohydrological conditions may drive the distribution of poor and rich fen species at a larger scale in the floating fen, due to the supply of minerotrophic groundwater. Interestingly, both rich and poor fen vegetation occurred in a mosaic, when electrical conductivity values at 50 cm depth were between 300 µS/cm and 450 µS/cm. Although environmental conditions were homogeneous at 50 cm, they differed markedly between rich and poor fen vegetation at 10 cm depth. Specifically, our measurements indicate that poor fen vegetation lowered porewater alkalinity, bicarbonate concentrations and pH. No effects of rich fen vegetation at 10 cm depth on biogeochemistry was measured. However, rich fen litter had a higher mineralization rate than poor fen litter, which increases the influence of minerotrophic water in rich fen habitat. Conclusions These results strengthen our hypothesis that species can drive formation of vegetation mosaics under environmentally homogeneous conditions in a floating fen. Positive intraspecific self‐facilitating mechanisms and negative species interactions could be responsible for a stable coexistence of species, even leading to local ecosystem engineering by the species, explaining the local vegetation mosaic at the microscale level in a floating fen.

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Field evidence for buoyancy-driven water flow in a Sphagnum dominated peat bog

Cited by 7 publications

References 29 publications

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [¹⁵N]nitrate–bromide double-tracer study

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [¹⁵N]nitrate–bromide double-tracer study

Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

Self‐facilitation and negative species interactions could drive microscale vegetation mosaic in a floating fen

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Field evidence for buoyancy-driven water flow in a Sphagnum dominated peat bog

Cited by 7 publications

References 29 publications

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [15N]nitrate–bromide double-tracer study

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [15N]nitrate–bromide double-tracer study

Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

Self‐facilitation and negative species interactions could drive microscale vegetation mosaic in a floating fen

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Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [¹⁵N]nitrate–bromide double-tracer study

Release of nitrous oxide and dinitrogen from a transition bog under drained and rewetted conditions due to denitrification: results from a [¹⁵N]nitrate–bromide double-tracer study