Data extracted in May 2022
Fiche created in December 2023

Note to the reader: This general fiche summarises all the environmental and climate impacts of PEATLAND MANAGEMENT found in a review of 4 synthesis papers[1]. These papers were selected from an initial number of 471 obtained through a systematic literature search strategy, according to the inclusion criteria reported in section 4. The impacts reported here are those for which there is scientific evidence available in published synthesis papers, what does not preclude the farming practice to have other impacts on the environment and climate still not covered by primary studies or by synthesis papers.

The synthesis papers review a number of primary studies ranging from 8 to 93. Therefore, the assessment of impacts relies on a large number of results from the primary studies, obtained mainly in field conditions, or sometimes in lab experiments or from model simulations.

1.      DESCRIPTION OF THE FARMING PRACTICE

  • Description:
    • A peatland is a type of wetland with a naturally accumulated layer of peat at the surface due to organic matter production exceeding decomposition.[2]
    • Peatlands are generally classified as bogs and fens. Bogs are fed mainly by rain and snow, while fens develop in landscape depressions and are fed with surface and/or ground water. Other names referring to peatlands found in this review are swamp, and wet heath, though the search string included more synonyms (see section 4). Carbon-rich soils are included in this definition. These soils have and organic layer usually with >15 % of organic matter. However, the synthesis papers included in this review do not clearly define what they consider carbon-rich soils and thus we rely on authors’ knowledge and criteria to include individual studies in their reviews.
    • This review focuses on peatlands under agricultural use and thus, and though not clearly stated on the papers reviewed, includes mostly drained peatlands.
    • This review includes interventions towards an improved and more sustainable management of peatlands. Specific interventions have been proposed such as low tillage, ban of burning, paludiculture, etc.[3]
    • In this literature review we have found evidence for the following management interventions:
      • No fertilisation. Fertilisers are natural or synthetic substances containing chemical elements such as nitrogen (N), phosphorus (P) and potassium (K) that are applied to soils to improve growth and productiveness of plants.[4] Fertilisation, and in particular N inputs in wetlands, might promote greenhouse gas emissions by changing element cycling.[5] Here, no fertilised peatlands are compared to fertilised ones.
      • Grazing is a method of animal husbandry in which livestock are allowed to feed outdoors consuming wild vegetation. The direction and magnitude of grazing impacts on ecosystem properties depends on grazing management such as stocking density, grazing duration and grazer species.[6] Here, grazed peatlands (comprising different management intensities and levels of drainage) are compared to mowed peatlands.
      • No burning. Burning is a routinely vegetation management practice conducted in some in some areas with the objective of stimulating the growth of grasses, maintaining these areas in young productive successional stages and increasing heterogeneity at the landscape scale and thus, supporting biodiversity.[7] However, peatland burning releases carbon to the atmosphere and banning this practice has been suggested as a measure to reduce GHG emissions.
      • Low intensity farming comprises a wide variety of farming practices analysed together and that refer mainly to the maintenance of permanent and extensive grasslands and fallowing in peatlands, including extensive livestock grazing, mowing and the lack of fertiliser inputs.[8]
    • Key descriptors:
      • These fiches focus on peatlands and the management practices conducted in these habitats. However, some of these farming practices are also explored more broadly without distinguishing the habitat type devoted to agricultural use in other sets of fiches (i.e, organic fertilisation and grazing fiches).
      • This review does not include peatland conservation or restoration, which are assessed in separate sets of fiches (i.e., peatland conservation and restoration).

2.     EFFECTS OF THE FARMING PRACTICE ON CLIMATE AND ENVIRONMENTAL IMPACTS

We reviewed the impacts on peatlands of different management practices, namely, the banning of fertilisation, banning of burning, grazing, and low intensity farming (interventions) compared, respectively, to fertilised, burned, mowed and high intensity farmed (in this case, intensively grazed) peatlands as (comparators).

The table below shows the number of synthesis papers with statistical tests reporting i) a significant difference between the Intervention and the Comparator, that is to say, a significant statistical effect, which can be positive or negative; or ii) a non-statistically significant difference between the Intervention and the Comparator. In addition, we include, if any, the number of synthesis papers reporting relevant results but without statistical test of the effects. Details on the quality assessment of the synthesis papers can be found in the methodology section of this WIKI.

Out of the 4 selected synthesis papers, 4 included studies conducted in Europe, and 3 have a quality score higher than 50%.

Table 1: Summary of effects. Number of synthesis papers reporting positive, negative or non-statistically significant effects on environmental and climate impacts. The number of synthesis papers reporting relevant results but without statistical test of the effects are also provided. When not all the synthesis papers reporting an effect are of high quality, the number of synthesis papers with a quality score of at least 50% is indicated in parentheses. Some synthesis papers may report effects for more than one impact, or more than one effect for the same impact.

 

 

 

 

Statistically tested

Non-statistically tested

Impact

Metric

Intervention

Comparator

 Significantly positive

Significantly negative

Non-significant

Increase Biodiversity

Biodiversity

No burning

Burning

0

0

0

1 (0)

Decrease GHG emissions

CH4 emissions

Grazing

Mowing

0

0

1

0

Low intensity farming

High intensity farming

0

0

1

0

No fertilisation

Fertilisation

0

0

1

0

Decrease GHG emissions

N2O emissions

Low intensity farming

High intensity farming

0

0

1

0

No fertilisation

Fertilisation

1

0

0

0

Increase Soil biological quality

Soil biological quality

No fertilisation

Fertilisation

0

1

0

0

Increase Crop yield

Crop yield

No fertilisation

Fertilisation

0

1

0

0

3.      FACTORS INFLUENCING THE EFFECTS ON CLIMATE AND ENVIRONMENTAL IMPACTS

The factors significantly influencing the size and/or direction of the effects on the impacts, according to the synthesis papers included in this review, are reported below. Details about the factors can be found in the summaries of the meta-analyses available in this WIKI.

Table 2: List of factors reported to significantly affect the size and/or direction of the effects on environmental and climate impacts, according to the synthesis papers reviewed. The reference number of the synthesis papers where those factors are explored is given in parentheses.

Impact

Factors

Soil biological quality

Climate (Ref1), Fertiliser type (Ref1) and N application rate (Ref1)

Crop yield

P application rate (Ref3), Productivity without P fertilisation (Ref3) and Soil P test at the beginning of the experimemt (Ref3)

4.     SYSTEMATIC REVIEW SEARCH STRATEGY

Table 3: Systematic review search strategy - methodology and search parameters.

Parameter

Details

Keywords

WOS:
1) TS=("wetland*" OR "marsh*" OR "fen*" OR "peatland*" OR "carbon-rich soil*" OR "carbon rich soil*" OR "wet meadow*" OR "wet soil*" OR "peat layer*" OR "water table*" OR "water layer*" OR “peat swamp*” OR “peat*” OR “water-saturated soil*” OR “black water*” OR “floodplain*” OR “histosol*” OR “mire*” OR “organic soil*” OR “estuar*” OR “mudflat*” OR "bog*") AND TS= ("rewett*" OR "land use change*" OR "land-use change*" OR "conserve*" OR "preserv*" OR "restor*" OR "conver*" OR "drain*" OR "undrain*" OR "protect*" OR "water retention" OR "colonization W/4 Thyfa" OR "colonization W/4 Sphagnum" OR "colonisation W/4 Thyfa" OR "colonisation W/4 Sphagnum" OR "set aside" OR “dry-rewet*” OR “irrigat*” OR “reveget*”) AND TS=("meta-analy*" OR "systematic* review*" OR "evidence map*" OR "global synthes*" OR "evidence synthes*" OR "research synthes*")
2) TS=("wetland*" OR "marsh*" OR "fen*" OR "peatland*" OR "carbon-rich soil*" OR "carbon rich soil*" OR "wet meadow*" OR "wet soil*" OR "peat layer*" OR "water table*" OR "water layer*" OR “peat swamp*” OR “peat*” OR “water-saturated soil*” OR “black water*” OR “floodplain*” OR “histosol*” OR “mire*” OR “organic soil*” OR “estuar*” OR “mudflat*”) AND TS= ("plough*" OR "till*" OR "drain*" OR "water use" OR "machinery" OR "integrated pest management*" OR "IPM" OR "fertilis*" OR "fertiliz*" OR "paludicult*" OR "extensive W/4 management*" OR “burn*” OR “sustainable W/4 management*” OR “traditional W/4 management*” OR “prevention W/4 inva*” OR “eradication W/4 inva*” OR “control w/4 inva*” OR “graz*” OR “afforest*”) AND TS=("meta-analy*" OR "systematic* review*" OR "evidence map*" OR "global synthes*" OR "evidence synthes*" OR "research synthes*")

 and

SCOPUS:
1) (SUBJAREA(AGRI OR ENVI) AND TITLE-ABS-KEY("wetland*" OR "marsh*" OR "fen*" OR "peatland*" OR "carbon-rich soil*" OR "carbon rich soil*" OR "wet meadow*" OR "wet soil*" OR "peat layer*" OR "water table*" OR "water layer*" OR “peat swamp*” OR “peat*” OR “water-saturated soil*” OR “black water*” OR “floodplain*” OR “histosol*” OR “mire*” OR “organic soil*” OR “estuar*” OR “mudflat*” OR "bog*") AND TITLE-ABS-KEY("rewett*" OR "land use change*" OR "land-use change*" OR "conserve*" OR "preserv*" OR "restor*" OR "conver*" OR "drain*" OR "undrain*" OR "protect*" OR "water retention" OR "colonization W/4 Thyfa" OR "colonization W/4 Sphagnum" OR "colonisation W/4 Thyfa" OR "colonisation W/4 Sphagnum" OR "set aside" OR “dry-rewet*” OR “irrigat*” OR “reveget*”) AND TITLE-ABS-KEY("meta-analy*" OR "systematic* review*" OR "evidence map*" OR "global synthes*" OR "evidence synthes*" OR "research synthes*"))
2) (SUBJAREA(AGRI OR ENVI) AND TITLE-ABS-KEY("wetland*" OR "marsh*" OR "fen*" OR "peatland*" OR "carbon-rich soil*" OR "carbon rich soil*" OR "wet meadow*" OR "wet soil*" OR "peat layer*" OR "water table*" OR "water layer*" OR “peat swamp*” OR “peat*” OR “water-saturated soil*” OR “black water*” OR “floodplain*” OR “histosol*” OR “mire*” OR “organic soil*” OR “estuar*” OR “mudflat*”) AND TITLE-ABS-KEY("plough*" OR "till*" OR "drain*" OR "water use" OR "machinery" OR "integrated pest management*" OR "IPM" OR "fertilis*" OR "fertiliz*" OR "paludicult*" OR "extensive W/4 management*" OR “burn*” OR “sustainable W/4 management*” OR “traditional W/4 management*” OR “prevention W/4 inva*” OR “eradication W/4 inva*” OR “control w/4 inva*” OR “graz*” OR “afforest*”) AND TITLE-ABS-KEY("meta-analy*" OR "systematic* review*" OR "evidence map*" OR "global synthes*" OR "evidence synthes*" OR "research synthes*"))

Time reference

No time restriction.

Databases

Web of Science and Scopus: run on 01 May 2022

Exclusion criteria

The main criteria that led to the exclusion of a synthesis paper are: 
 1) The paper did not deal with peatlands or carbon-rich soils or the effects on peatlands could not be disentangled from those on wetlands, 2) The paper was either a non-systematic review, a non-quantitative systematic review, or a meta-regression without mean effect sizes and 3) The paper is not written in English. 

The search returned 470 synthesis papers from WOS and SCOPUS on Peatland management plus other 1 retrieved in the search of other farming practices, potentially relevant for the practice object of our fiche. 
From the 471 potentially relevant synthesis papers, 332 were excluded after reading the title and abstract, and 135 after reading the full text according to the above-mentioned criteria. Finally, 4 synthesis papers were selected.

5.     SYNTHESIS PAPERS INCLUDED IN THE REVIEW

Table 4: List of synthesis papers included in this review. More details can be found in the summaries of the meta-analyses.

Ref Num

Author(s)

Year

Title

Journal

DOI

Ref1

Chen, M; Chang, L; Zhang, J; Guo, F; Vymazal, J; He, Q; Chen, Y

2020

Global nitrogen input on wetland ecosystem: The driving mechanism of soil labile carbon and nitrogen on greenhouse gas emissions

ENVIRONMENTAL SCIENCE AND ECOTECHNOLOGY, 4, 100063.

10.1016/j.ese.2020.100063

Ref2

Haddaway, NR; Burden, A; Evans, CD; Healey, JR; Jones, DL; Dalrymple, SE; Pullin, AS

2014

Evaluating effects of land management on greenhouse gas fluxes and carbon balances in boreo-temperate lowland peatland systems

ENVIRONMENTAL EVIDENCE, 3(1), 1-30.

10.1186/2047-2382-3-5

Ref3

Valkama, E; Uusitalo, R; Ylivainio, K; Virkajarvi, P; Turtola, E

2009

Phosphorus fertilization: A meta-analysis of 80 years of research in Finland

AGRICULTURE ECOSYSTEMS AND ENVIRONMENT, 130, 75-85.

10.1016/j.agee.2008.12.004

Ref4

Stewart, GB; Coles, CF; Pullin, AS

2005

Applying evidence-based practice in conservation management: Lessons from the first systematic review and dissemination projects

BIOLOGICAL CONSERVATION, 126, 270-278.

10.1016/j.biocon.2005.06.003

 

Disclaimer: These fiches present a large amount of scientific knowledge synthesised to assess farming practices impacts on the environment, climate and productivity. The European Commission maintains this WIKI to enhance public access to information about its initiatives. Our goal is to keep this information timely and accurate. If errors are brought to our attention, we will try to correct them. However, the Commission accepts no responsibility or liability whatsoever with regard to the information on these fiches and WIKI.


[1] Synthesis research papers include either meta-analysis or systematic reviews with quantitative results. Details can be found in the methodology section of the WIKI.

[2] Joosten, H & Clarke, D. 2002: Wise use of mires and peatlands: Background and principles including a framework for decision making. IMCG/IPS.

[3] Joosten, et al. 2012. Peatlands—Guidance for climate change mitigation, conservation, rehabilitation and sustainable use. Mitigation of climate change in Agriculture Series 5 (FAO).

[4] https://ec.europa.eu/eurostat/statistics-explained/index.php?title=Glossary:Fertiliser

[5] Chen, M; Chang, L; Zhang, J et al. 2020. Global nitrogen input on wetland ecosystem: The driving mechanism of soil labile carbon and nitrogen on greenhouse gas emissions. Environmental Science and Ecotechnology, 4, 100063.

[6] Paz-Kagan, T; Ohana-Levi, N; Herrmann, I et al. 2016. Grazing intensity effects on soil quality: a spatial analysis of a Mediterranean grassland. Catena, 146, 100–110.

[7] Stewart, GB; Coles, C F; Pullin, AS. 2005. Applying evidence-based practice in conservation management: Lessons from the First systematic review and dissemination projects, 126, 270–278.

[8] Haddaway, NR; Burden, A; Evans, CD; et al. 2014. Evaluating effects of land management on greenhouse gas fluxes and carbon balances in boreo-temperate lowland peatland systems. Environmental Evidence, 3.

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