Restoration of rare bryophytes in degraded rich fens: The effect of sod-and-moss removal

https://doi.org/10.1016/j.jnc.2020.125928Get rights and content

Highlights

  • Rich fens are biodiversity hotspots disappearing due to anthropogenic interventions.

  • Fen bryophytes, key for vital, rich fens, are threatened by expansive Sphagna.

  • Sod-and-moss removal supports species richness and fen bryophytes and suppresses expansive Sphagna.

  • Further research is needed to test the effectiveness and applicability of sod-and-moss removal over a longer period.

Abstract

Rich fens are known as biodiversity hot spots among peatlands encompassing many endangered bryophytes. In some European regions, specialised rich-fen bryophytes, including red-listed species, have been outcompeted by expansive Sphagnum species and competitively strong vascular plants. One of the main causes of the rapid succession was a cessation of traditional management such as scything, raking, or occasional grazing. Most of the current rich fens in Central and Western Europe depend on such management-related disturbances because they have been initiated or altered by humans. Removal of expansive Sphagnum species together with tussocks of graminoids is occasionally suggested to reverse the succession to previous rich fen stage before re-establishing the traditional management or its imitation. We carried out such treatment on 31 sites to restore microhabitats for fen-specialised bryophytes. Expansive Sphagnum species declined after the sod-and-moss removal. After one and a half years, the treated plots showed a gradual increase in species richness and abundance of fen-specialised bryophytes, which, however, only slightly increased in total cover. In regions where no Sphagnum species are endangered or legally protected, a sod-and-moss removal is a possible tool for restoration of rich fen vegetation that developed to poor fens because of modern anthropogenic interventions in the agricultural landscapes. However, its repetition after approximately a decade might be required due to the rapid regeneration of expansive Sphagnum species. Yet, further research is needed on the effectiveness and applicability of sod-and-moss removal over a longer period.

Introduction

Biodiverse base-rich fens became a highly endangered European habitat. The main causes of their reduction are acidification, eutrophication, groundwater pollution, hydrological deterioration, climate change or cessation of traditional management (Chytrý et al., 2019; Essl et al., 2012; Hájek et al., 2015; Janssen et al., 2016; Kooijman, 2012; Kooijman & Paulissen, 2006; Rion et al., 2018; Wassen et al., 2005). These processes triggered a shift from typical sedge-moss base-rich fen vegetation to more common vegetation types such as wet meadows with a dominance of tussock-forming grasses such as Deschamspia cespitosa, Molinia caerulea agg. (Diemer et al., 2009; Hájková et al., 2009; Rion et al., 2018), reed-bed or woodland species (Güsewell, 2003; Jabłońska et al., 2019; Koch & Jurasinski, 2015; Middleton et al., 2006) or to acidified poor-fen communities dominated by fast-growing Sphagnum species (Beltman et al., 2001; Granath et al., 2010; Kooijman, 2012; Lamers et al., 2015; Paulissen et al., 2014). This vegetation shift has frequently resulted in biodiversity loss.

Rich fens are out of all peatlands one of the most biodiverse habitats, encompassing a significant proportion of specialised plant species (Bedford & Godwin, 2003; Peterka et al., 2017; Wheeler, 1988). A substantial part of the ground is occupied by fen-specialised bryophytes such as so-called brown mosses, i.e. non-sphagnaceous weft-forming bryophytes from family Amblystegiaceae, e.g. Campylium stellatum or family Calliergonaceae, e.g. Hamatocaulis vernicosus and calcium tolerant species, e.g. Sphagnum contortum or S. warnstorfii (Vitt et al., 1995). Their dominance may affect fen functioning. Brown mosses grow laterally and often create extensive mats, covering most of the ground, alleviate harsh environmental conditions and facilitate seedling emergence and survival (Clapham, 1940; Crowley, 2009). However, even in seemingly well-preserved fens, brown moss patches virtually disappeared in some regions (Hájek et al., 2015) which may also affect endangered vascular plants (Singh et al., 2019). One of the reasons of brown moss disappearance is the expansion of fast-growing calcifuge Sphagnum species and nutrient-demanding vascular plants, which act as competitors and often overgrow small-stature bryophytes, vascular plants or their seedlings (Hájek et al., 2015; Juutinen, 2011; Neuhäusl, 1975; Nordbakken et al., 2004; Ohlson et al., 2001; Paulissen et al., 2014). Sphagnum mosses, protected legally in some countries and being major global peat-formers and carbon sinkers, here paradoxically act as mediators of biodiversity loss.

Most of the current temperate fens are semi-natural ecosystems, grazed since the Neolithic Era and supplying hay since the Iron Age (Cromsigt, 2000; Middleton, 1999). During the pre-industrial period, many fens were drained due to increasing hay-yield demand in densely populated regions. In addition, new fen grasslands have appeared after cutting of alder or spruce fen woodlands (Hájková et al., 2012; Jamrichová et al., 2018). Despite the fen drainage and susceptibility to secondary succession, haymaking (scything and raking), combined with occasional grazing and litter/moss raking for bedding, sustained mosaic heterogeneity typical for sedge-moss fen vegetation. This traditional management maintained high fen biodiversity for decades through slowing down the natural succession (Grootjans et al., 2006; Hájek et al., 2015; Verhoeven & Bobbink, 2001). However, since the 1950s the traditional land use of fens was abandoned, due to intensified agriculture which led to rapid successional shift and loss of characteristic fen-specialised plant species (Hájková et al., 2009; Koch & Jurasinski, 2015; Middleton et al., 2006; Moen et al., 1999; Peintinger & Bergamini, 2006; Tyler, 1984).

Rich fens have undergone a significant decline in Western, West-Central and Southern Europe. They are virtually extinct in several regions where only their last remnants can be found. Their deterioration was mainly caused by agricultural and industrial development (Bragg & Lindsay, 2003; Grzybowski & Glińska-Lewczuk, 2020; Janssen et al., 2016). Similar influences have negatively affected rich fens also in East-Central Europe, including our study area. Yet, losses have so far been less severe, and the region still harbours rich fen types that are virtually extinct further west and have great importance for the maintenance of the continent’s biodiversity (Bragg & Lindsay, 2003).

Management measures such as scything, mowing, grazing or burning are recommended to tackle successional shift (Billeter et al., 2003; Hansson & Fogelfors, 2000; Hogg et al., 1995; Middleton et al., 2006; Mitlacher et al., 2002; Øien & Moen, 2001; van Belle et al., 2006; Van Diggelen et al., 1996). However, over the past decades, we observed a loss of fen specialists and the increase in nutrient-demanding generalists, even despite prescribed conservation-oriented haymaking or grazing in Central Europe (Bergamini et al., 2009; Hájek et al., 2015, 2020). Rich fens are protected at the European level under Habitats Directive Annex I (Directive, 1992). Besides, rich fens belong currently to overall 10 % of the most endangered, red-listed habitats within European Union countries based on a decline over the past 50 years and more long-term historical times (Janssen et al., 2016). In the Czech Republic, the current state of rich fens is critical. They cover, in different stages of conditions, the last 566 ha (expert estimate - AOPK ČR, 2018), which, in total, is less than 0.01 % of the area of the Czech Republic. According to IUCN criteria, they belong to a few critically endangered habitats in the Czech Republic according to the A1 and A3 criteria (reduction in quantity >90 %; Chytrý et al., 2019). In the lowlands, many fens have been either completely transformed to arable land or substantially degraded due to hydrological change and eutrophication (Bragg & Lindsay, 2003). Successional changes after cessation of traditional management are one of the most critical threatening factors of Czech habitats (Chytrý et al., 2019).

Remaining Czech rich fens are mown by nature conservation authorities that maintain treeless fen nature and reduce litter accumulation. However, annual mowing is failing to restore small-scale heterogeneity, which is necessary for the existence of sedge-moss rich-fen vegetation. It further seems not to prevent the expansion of acidophilous Sphagnum species, which cause a shift to poor-fen communities (Hájek et al., 2015; Singh et al., 2019).

Top-soil removal (also referred to as peat or sod-stripping) is an invasive technique often used to rehabilitate deeply drained and eutrophicated peatlands, i.e. former agricultural areas. The removal of degraded peat layer may quickly remove nutrients, achieve wetter conditions, and enhance the influence of groundwater in the upper soil layer, and consequently improve local biodiversity. However, it has a high initial cost, due to the requirement of the excavators for deep soil removal, and is not suited for the peatlands where natural communities rich in specialists still occur (Emsens et al., 2015; Klimkowska et al., 2010, 2015; Patzelt et al., 2001; Ramseier, 2000; Smolders et al., 2008; Van Duren et al., 1998; Verhagen et al., 2001; Zak et al., 2018).

We aim to test a rarely used and relatively low-cost fen restoration measure, the removal of a shallow upper layer of sod and moss, performed mechanically by rakes, in fens near to natural state, but heavily encroached by few fast-growing Sphagnum mosses and tussock graminoids (Beltman et al., 2001; Mälson & Rydin, 2007). We applied this treatment on six minerotrophic fens in the Czech Republic, which harbour the remnant populations of fen-specialised bryophytes being suppressed by expanding acidicole Sphagnum species. We aim to create a heterogeneous ground layer to initiate the development of the original sedge-moss structure of rich fens.

Section snippets

Selection of study area

We proceeded the sod-and-moss removal in six minerotrophic fens, which are isolated habitats under nature protection in an unprotected agricultural landscape (pH 5.7–6.7, conductivity [EC] 104–315 μS.cm-1) located in the western part of the Bohemian Massif (Fig. 1, Table 1). These localities are sloping fens or a combination of sloping and basin fens (Charman, 2002) with similar water regime, i.e. slightly fluctuating water level in the root zone creating desirable conditions for

Community-level analyses

Detrended Correspondence Analysis sorted samples from the first and the last sampling period along the two principal gradients (Fig. 3). The first one stretches from samples with expansive Sphagnum species (S. palustre, S. flexuosum) to samples with target bryophytes. The second principal gradient sorts samples predominantly on the positive end of the first axis (i.e., samples with fen-specialised bryophytes), plausibly according to calcium tolerance, with brown mosses of calcium-rich habitats (

Increasing yet a low abundance of fen-specialised bryophytes after the sod-and-moss removal

Our study addressed the question of whether prescribed removal of sod and moss in rich fens undergoing succession to poor fens or tussock grasslands would support the communities of fen-specialised bryophytes and suppress expansive Sphagnum species. The plots initially dominated by expansive Sphagnum species (S. flexuosum, S. palustre, S. teres) shifted to early successional stages with the occurrence of target bryophytes. The total cover of target bryophytes was, however, low after one and a

Conclusion

The sod-and-moss removal applied in deteriorated rich fens, strongly dominated by expansive Sphagnum species or vascular plants, seems to be a promising tool to restore rich fen patches with brown mosses and other specialised fen bryophytes, but has certain limitations. In our study, the total cover of fen-specialised bryophytes was low after one and a half years since the treatment application, while a cover of expansive Sphagnum species started to recover insignificantly. Yet, only a few

Data accessibility statement

The primary data that support the findings of this study are available from the corresponding author, [PS], upon reasonable request.

CRediT authorship contribution statement

Patrícia Singh: Formal analysis, Writing - original draft, Writing - review & editing. Ester Ekrtová: Conceptualization, Investigation, Writing - review & editing. Eva Holá: Conceptualization, Investigation, Writing - review & editing, Formal analysis. Táňa Štechová: Conceptualization, Investigation, Writing - review & editing. Stanislav Grill: Formal analysis. Michal Hájek: Writing - review & editing, Funding acquisition.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

The data processing and preparation of the paper was funded by the Czech Science Foundation (project no. 19-01775S). The funding of sod-and-moss removal itself was arranged by J. Janová, A. Hofhanzl, and V. Kodet. We thank all colleagues who made the realisation of the sod-and-moss removal possible. We are grateful to T. Velehradská and F. Lysák for inspiration to carry out sod-and-moss removal, P. Šmilauer for developing the software computing for the transition matrix and M. Štech for

References (108)

  • A.M. Jansen et al.

    Restoration of Cirsio-Molinietum wet meadows by sod cutting

    Ecological Engineering

    (1996)
  • A. Klimkowska et al.

    Prospects for fen meadow restoration on severely degraded fens

    Perspectives in Plant Ecology, Evolution and Systematics

    (2010)
  • A.M. Kooijman et al.

    Extinction and reintroduction of the bryophyte Scorpidium scorpioides in a rich-fen spring site in the Netherlands

    Biological Conservation

    (1994)
  • K. Mälson et al.

    The regeneration capabilities of bryophytes for rich fen restoration

    Biological Conservation

    (2007)
  • T. Štechová et al.

    The requirements of the rare moss, Hamatocaulis vernicosus (Calliergonaceae, Musci), in the Czech Republic in relation to vegetation, water chemistry and management

    Biological Conservation

    (2007)
  • C. Tyler

    Calcareous fens in south Sweden. Previous use, effects of management and management recommendations

    Biological Conservation

    (1984)
  • E. Vicherová et al.

    Calcium intolerance of fen mosses: Physiological evidence, effects of nutrient availability and successional drivers

    Perspectives in Plant Ecology, Evolution and Systematics

    (2015)
  • E. Vicherová et al.

    Sphagnum establishment in alkaline fens: Importance of weather and water chemistry

    The Science of the Total Environment

    (2017)
  • AOPK ČR

    Údaje o rozloze biotopů České republiky

    (2018)
  • T. Arnesen

    Vegetation dynamics following trampling in rich fen at Sølendet, Central Norway; a 15 year study of recovery

    Nordic Journal of Botany

    (1999)
  • B.L. Bedford et al.

    Fens of the united states: Distribution, characteristics, and scientific connection versus legal isolation

    Wetlands

    (2003)
  • F. Bengtsson et al.

    Photosynthesis, growth, and decay traits in Sphagnum – A multispecies comparison

    Ecology and Evolution

    (2016)
  • A. Bergamini et al.

    Effects of increased nutrient supply on bryophytes in montane calcareous fens

    Journal of Bryology

    (2001)
  • R. Billeter et al.

    Differential and reversible responses of common fen meadow species to abandonment

    Applied Vegetation Science

    (2003)
  • D. Boeye et al.

    Nutrient limitation in species-rich lowland fens

    Journal of Vegetation Science

    (1997)
  • O. Bragg et al.

    Strategy and action plan for mire and peatland conservation in central Europe: Central European peatland project (CEPP)

    (2003)
  • D. Charman

    Peatlands and environmental change

    (2002)
  • A.R. Clapham

    The role of bryophytes in the calcareous fens of the Oxford District

    The Journal of Ecology

    (1940)
  • D. Cobbaert et al.

    Experimental restoration of a fen plant community after peat mining

    Applied Vegetation Science

    (2004)
  • J. Cromsigt

    The large herbivores of the Eurasian continent. A reference guide for the Large Herbivore Initiative (LHI)

    (2000)
  • K. Crowley

    Mosses influence vascular plants in rich fens through effects on the biogeochemistry of shallow soils

    (2009)
  • S. Diaz et al.

    Plant functional traits and environmental filters at a regional scale

    Journal of Vegetation Science

    (1998)
  • M. Diemer et al.

    Abandonment alters community composition and canopy structure of Swiss calcareous fens

    Applied Vegetation Science

    (2009)
  • K. Dierßen

    Distribution, ecological amplitude and phytosociological characterization of European bryophytes

    (2001)
  • H. Directive

    Council Directive 92/43/EEC of 21 May 1992 on the conservation of natural habitats and of wild fauna and flora

    Official Journal of the European Union

    (1992)
  • J.A. Dracup et al.

    On the definition of droughts

    Water Resources Research

    (1980)
  • F. Essl et al.

    Vulnerability of mires under climate change: Implications for nature conservation and climate change adaptation

    Biodiversity and Conservation

    (2012)
  • B.C. Forbes

    The importance of bryophytes in the classification of human-disturbed high arctic vegetation

    Journal of Vegetation Science

    (1994)
  • Y. Fujita et al.

    Low investment in sexual reproduction threatens plants adapted to phosphorus limitation

    Nature

    (2014)
  • M. Gordon

    Gmisc: Descriptive statistics, transition plots, and more

    R Package, Version

    (2016)
  • G. Granath et al.

    Rapid ecosystem shifts in peatlands: Linking plant physiology and succession

    Ecology

    (2010)
  • A. Grootjans et al.

    Assessing the restoration prospects of degraded fens

    (1995)
  • A.P. Grootjans et al.

    Hydrological landscape settings of base-rich fen mires and fen meadows: An overview

    Applied Vegetation Science

    (2006)
  • U. Gunnarsson et al.

    Dynamics or constancy in Sphagnum dominated mire ecosystems? A 40‐year study

    Ecography

    (2002)
  • S. Güsewell

    Management of Phragmites australis in Swiss fen meadows by mowing in early summer

    Wetlands Ecology and Management

    (2003)
  • M. Hájek et al.

    Changes in the moss layer in Czech fens indicate early succession triggered by nutrient enrichment

    Preslia

    (2015)
  • P. Hájková et al.

    How can we effectively restore species richness and natural composition of a Molinia‐invaded fen?

    Journal of Applied Ecology

    (2009)
  • P. Hájková et al.

    Origin and contrasting succession pathways of the Western Carpathian calcareous fens revealed by plant and mollusc macrofossils

    Boreas

    (2012)
  • P. Hájková et al.

    Using a new database of plant macrofossils of the Czech and Slovak Republics to compare past and present distribution of hypothetically relict fen mosses

    Preslia

    (2018)
  • M. Hansson et al.

    Management of a semi-natural grassland; results from a 15-year-old experiment in southern Sweden

    Journal of Vegetation Science

    (2000)
  • Cited by (12)

    • Conservation and restoration of Central European fens by mowing: A consensus from 20 years of experimental work

      2022, Science of the Total Environment
      Citation Excerpt :

      Continued hydrological and nutrient changes lower habitat extremeness and trigger secondary succession from sedge-moss ecosystems to highly productive tall-forbs, tall-grass and shrubby ecosystems (Diemer et al., 2001), characterised by lower representation of habitat specialists (Bergamini et al., 2009) or even lower overall species richness (Opdekamp et al., 2012). Sometimes Sphagnum mosses may expand at the expense of endangered brown mosses and tiny vascular plant species inhabiting fens (Kooijman, 2012; Singh et al., 2019, 2021). Not all fens are environmentally extreme enough to prevent natural succession to more productive ecosystems.

    View all citing articles on Scopus
    View full text