Effect of Water Content Components on Desiccation and Recovery in Sphagnum Mosses

Hájek, Tomáš; Beckett, Richard P.

doi:10.1093/aob/mcm287

Cited by 101 publications

(117 citation statements)

References 23 publications

(35 reference statements)

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“…In fact, all samples have a high water capacity around pF = 2. During meteorological conditions favouring prolonged periods of drying, the decrease in pressure head is slowed down by the release of this water, and low pressure heads leading to desiccation and cessation of photosynthesis (Hájek and Beckett, 2008) are reached only slowly. Commensurate with the WRC, the slope of the HCC around pF = 2 decreases as water drains from hyaline cells and their skeleton material, and hydraulic conductivity remains at values of approximately 10 −2 cm day −1 until approx.…”

Section: Change In Pore-system Characteristics With Depthmentioning

confidence: 99%

“…to photosynthesize critically depends on the water regime and is limited to the topmost centimetres of the bog profile where growth occurs (Clymo, 1973). Under field conditions, soil hydraulic properties (SHP) control the water regime in the topmost, growing part of the peat profile and are thus a critical factor for moss growth and survival (Hájek and Beckett, 2008). The importance of capillary, film, and vapour flow processes for upward water fluxes in moss and peat has been emphasized by Hayward and Clymo (1982) and Price et al (2009), while SHP accounting for these processes have only recently been identified by Weber et al (2017a) for a limited number of samples.…”

Section: Introductionmentioning

confidence: 99%

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A pore-size classification for peat bogs derived from unsaturated hydraulic properties

Weber

Iden

Durner

2017

Hydrol. Earth Syst. Sci.

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Abstract. In ombrotrophic peatlands, the moisture content of the acrotelm (vadoze zone) controls oxygen diffusion rates, redox state, and the turnover of organic matter. Thus, variably saturated flow processes determine whether peatlands act as sinks or sources of atmospheric carbon, and modelling these processes is crucial to assess effects of changed environmental conditions on the future development of these ecosystems. We show that the Richards equation can be used to accurately describe the moisture dynamics under evaporative conditions in variably saturated peat soil, encompassing the transition from the topmost living moss layer to the decomposed peat as part of the vadose zone. Soil hydraulic properties (SHP) were identified by inverse simulation of evaporation experiments on samples from the entire acrotelm. To obtain consistent descriptions of the observations, the traditional van GenuchtenMualem model was extended to account for non-capillary water storage and flow. We found that the SHP of the uppermost moss layer reflect a pore-size distribution (PSD) that combines three distinct pore systems of the Sphagnum moss. For deeper samples, acrotelm pedogenesis changes the shape of the SHP due to the collapse of inter-plant pores and an infill with smaller particles. This leads to gradually more homogeneous and bi-modal PSDs with increasing depth, which in turn can serve as a proxy for increasing state of pedogenesis in peatlands. From this, we derive a nomenclature and size classification for the pore spaces of Sphagnum mosses and define inter-, intra-, and inner-plant pore spaces, with effective pore diameters of > 300, 300-30, and 30-10 µm, respectively.

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Section: Change In Pore-system Characteristics With Depthmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A pore-size classification for peat bogs derived from unsaturated hydraulic properties

Weber

Iden

Durner

2017

Hydrol. Earth Syst. Sci.

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“…Still some important potential factors have not yet been studied including peat and water chemistry beyond simple ions and elements. Sphagnum peatlands are indeed generally characterized by gradients such as nutrients (nutrient-poor ombrotrophic bogs vs. rich fens), hydrology (wet hollow vs. dry hummocks), and acidity [14,22,23,52].…”

Section: Introductionmentioning

confidence: 99%

Fine-Scale Horizontal and Vertical Micro-distribution Patterns of Testate Amoebae Along a Narrow Fen/Bog Gradient

et al. 2010

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The ecology of peatland testate amoebae is well studied along broad gradient from very wet (pool) to dry (hummock) micro-sites where testate amoebae are often found to respond primarily to the depth to water table (DWT). Much less is known on their responses to finerscale gradients, and nothing is known of their possible response to phenolic compounds, which play a key role in carbon storage in peatlands. We studied the vertical (0-3, 3-6, and 6-9 cm sampling depths) micro-distribution patterns of testate amoebae in the same microhabitat (Sphagnum fallax lawn) along a narrow ecological gradient between a poor fen with an almost flat and homogeneous Sphagnum carpet (fen) and a "young bog" (bog) with more marked micro-topography and mosaic of poor fen and bog vegetation. We analyzed the relationships between the testate amoeba data and three sets of variables (1) "chemical" (pH, Eh potential, and conductivity), (2) "physical" (water temperature, altitude, i.e., Sphagnum mat micro-topography, and DWT), and (3) phenolic compounds in/from Sphagnum (water-soluble and primarily bound phenolics) as well as the habitat (fen/bog) and the sampling depth. Testate amoeba Shannon H′ diversity, equitability J of communities, and total density peaked in lower parts of Sphagnum, but the patterns differed between the fen and bog micro-sites. Redundancy analyses revealed that testate amoeba communities differed significantly in relation to Eh, conductivity, water temperature, altitude, water-soluble phenolics, habitat, and sampling depth, but not to DWT, pH, or primarily bound phenolics. The sensitivity of testate amoebae to weak environmental gradients makes them particularly good integrators of micro-environmental variations and has implications for their use in paleoecology and environmental monitoring. The correlation between testate amoeba communities and the concentration of water-soluble phenolic suggests direct (e.g., physiological) and/or indirect (e.g., through impact on prey organisms) effects on testate amoebae, which requires further research.

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“…We used the maximum quantum yield of the photosystem II (F v /F m ), an indicator of photosynthetic capacity and plant stress (Krause and Weis 1991), to assess post-fire recovery. The F v /F m ratio is a good indicator of the physiological state of the leaf photosynthetic system (Maxwell and Johnson 2000) and has been successfully used in Sphagnum (Hájek and Beckett 2008;Manninen et al 2011;Taylor et al 2017).…”

Section: Methodsmentioning

confidence: 99%

Sphagnum abundance and photosynthetic capacity show rapid short-term recovery following managed burning

Grau‐Andrés

Gray

Davies

2017

Plant Ecology & Diversity

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Background: Prescribed burning in peatlands is controversial due to concerns over damage to their ecological functioning, particularly regarding their key genus Sphagnum. However, empirical evidence is scarce. Aims: The aim of the article is to quantify Sphagnum recovery following prescribed burns. Methods: We completed nine fires at a raised bog in Scotland, achieving a range of fire severities by simulating drought in some plots. We measured Sphagnum cover and chlorophyll fluorescence F v /F m ratio (an estimate of photosynthetic capacity) up to 36 months post-fire. Results: Cover of dominant Sphagnum capillifolium was similar in unburnt and burnt plots, likely due to its high moisture content which prevented combustion. Burning decreased S. capillifolium F v /F m 5 months after fire from 0.67 in unburnt plots to 0.44 in low fire severity plots and 0.24 in higher fire severity (drought) plots. After 22 months, F v /F m in burnt plots showed a healthy photosynthetic capacity of 0.76 and no differences between severity treatments. Other Sphagnum species showed similar post-fire recovery though their low overall abundance precluded formal statistical analysis. Conclusions: S. capillifolium is resilient to low-moderate fire severities and the same may be true for a number of other species. This suggests that carefully applied managed burning can be compatible with the conservation of peatland ecosystem function.

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Effect of Water Content Components on Desiccation and Recovery in Sphagnum Mosses

Cited by 101 publications

References 23 publications

A pore-size classification for peat bogs derived from unsaturated hydraulic properties

A pore-size classification for peat bogs derived from unsaturated hydraulic properties

Fine-Scale Horizontal and Vertical Micro-distribution Patterns of Testate Amoebae Along a Narrow Fen/Bog Gradient

Sphagnum abundance and photosynthetic capacity show rapid short-term recovery following managed burning

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