best practices for managing soil organic matter in agriculture

Best practices for managing soil organic

matter in agriculture

Managing SOM in ‘upland’ agriculture

Fred Worrall

& Madeleine Bell

Dept. of Earth Sciences, University of

Durham

Contents Page

1. Introduction 6

2. Methodology 7

3. Pristine 11

4. Afforestation 22

5. Managed burning 29

6. Deforestation 35

7. Drainage 39

8. Drain-blocking 48

9. Grazing removal 56

10. Revegetation 60

11. Vegetation cutting 65

12. Vegetation change 66

13. Wildfire suppression 67

Summary & recommendations

Project summary and recommendations

1) The project would support the view that intact peat soils are net sinks of carbon and

greenhouse gases and

2) This project provides a method for assessing the pristine sink of any UK peat soil.

3) The project would suggest that the following land managements would improve the

carbon budget of peat soils over that achievable for the same soil under pristine

conditions

a. Afforestation – this will cause a shift of carbon from soil to biomass and the

benefit would be limited to the growth phase of the vegetation unless

harvesting and product substitution are considered. Furthermore, afforestation

would achieve greater carbon benefits if the peat soil was left intact and the

equivalent number of trees planted in mineral soils.

4) The project would suggest that the following managements would bring a carbon

benefit wherever they are possible:

a. Drain-blocking – this would lead to increases in the carbon budget, but results

would suggest that rises in greenhouse gas fluxes may occur.

b. Revegetation – this will improve both carbon and greenhouse gas budgets.

c. Cessation of burning – the present evidence is that this will lead to

improvements in both carbon and greenhouse gas budgets. However, the issue

of char production may alter this for some fires.

d. Grazing removal – this would improve both carbon and greenhouse gas

budgets.

5) The project would suggests that the following management/land-uses would bring a

disbenefit

a. Deforestation – this disbenefit may be constrained depending upon the re-use

of the land after deforestation and what use the harvested product is put to.

b. Drainage – may improve greenhouse gas loss but would increase carbon

losses.

6) The project could find little direct evidence of the consequences of the following:

wildfire suppression, vegetation change or vegetation cutting.

7) The project was very limited by two important gaps in our knowledge:

a. The number of studies that considered complete carbon budgets of any

environment are very limited and especially limited for managed

environments.

b. Even more limited were the number of studies which considered the change in

carbon budget before and after a management intervention.

8) All changes in carbon budget must be viewed in the light of cost of intervention or

management and the wider benefits or disbenefits.

Introduction

4

Summary & recommendations

5

Table 3. The summary of: effective sample size; probability of success for both carbon budget and greenhouse gas benefit (% - the latter includes

methane); magnitude of effect in terms of carbon; the timescale of the effect; and estimated cost of implementation for each management type.

The values in the brackets are the variance in the probability estimate. The carbon budgets are expressed relative to the soil, i.e. +ve values

express a gain of terrestrial carbon relative to the atmosphere. The timescale of change is given as a default value of 25 years, i.e. the time for C.

vulgaris to achieve maturity, this value maybe lower in some regions of the country.

Management Effective

sample size

Effective

sample

size (GHG)

Probability of

improvement

(Carbon)

Probability of

improvement

(GHG – includes

CH4)

Magnitude of effect

(tonnes C/km2/yr)

Timescale (yr) Cost

(/km2 or /km of ditch)

Afforestation 9.6 9.4 63 (±19) 81 (±28) +253 Only upto 70

years after planting

?

Managed burning 5.6 4.1 7 (±0.4) 40 (±2) -83 25 12800 – 20000

Cease burning 5.6 4.1 93 (±0.4) 60 (±2) +83 25 -12800 - -20000

Deforestation 0.8 0.3 19 (±14) 14 (±13) Depends upon use of site ? ?

Drainage 12.1 14.7 19 (±1) 47 (±6) -5 25 3000

Drain-blocking 10.3 11.3 55 (±11) 34 (±5) +5 25 3000

Grazing 3 2.3 65 (±27) 78 (±32) -3 ? ?

Revegetation 5.8 6.4 70 (±28) 45 (±9) +210 25 8800 - 270000

Vegetation cutting 0 0 50 (±50) 50 (±50) ? 25 12800 - 20000

Vegetation change 0 0 50 (±50) 50 (50) ? 25 22300 - 110000

Wildfire

suppression

0 0 50 (±50) 50 (±50) ? ? ?

Introduction

6

1. Introduction

The aim of this study is to review evidence from the literature and from computer modelling

in order to assess best practise for maintaining and improving soil organic matter in peat

soils. In order to do this we have made the following assumptions to limit the study:

1) We define the soils of concern as peat soils where we define peats as deep peats with

an organic layer deeper than suvh that an acrotelm/catotlem boundary is present – in

the UK this equates to on organic layer of approximately 40 cm depth. For high

organic soils (peats) the %SOC does not change and so managing soil organic matter

is about managing the fluxes of carbon to and from the soil and so the impact of

management is addressed in terms of fluxes and annual budgets.

2) We have not limited our study to just upland peat soils but have included raised bog

as well as blanket bog and mires, but we have not considered fens, which we take as

wetlands with large expanses of standing water, nor have we considered fen soils

converted for agriculture.

3) In geographical terms the studied considers data from the UK as a priority but also

considered data from Europe and North American, but data from the Arctic or areas

which are tundra were excluded.

4) We recognise that the context in which we considered organic soils is not stationary

especially in the light of climate change, but given the scarcity of studies we have

decided not to discriminate on the grounds of age of the study.

5) The study considers the following land use/land management types: drainage, drain-

blocked, managed burning, suppression of wildfire, afforestation, deforestation,

grazing removal, revegetation, vegetation change, and vegetation cutting. These are

all compared to a pristine case.

6) The study is focused upon the carbon budget of peat soils where the carbon budget is

defined as

42 CHdissCODOCPOCRPPFC (i)

Where: Fc = the total carbon budget (tonnes C/km2/yr); POC= the annual flux of POC

(tonnes C/km2/yr); DOC = annual DOC flux (tonnes C/km

2/yr); diss.CO2 = the annual

flux of excess dissolved CO2 (tonnes C/km2/yr); and CH4 = the annual methane flux

(tonnes C/km2/yr). Between studies the exact definitions of each of these components

of the budget may vary and we have to rely on the individual authors.

Methodology

7

2. Methodology The study took two approaches: a literature review and analysis of computer modelling

results

2.1. Literature analysis

We reviewed the literature for information on annual budgets for each management/land-use

types because the number of studies that considered a whole carbon budget are very few(only

5) studies that considered individual components had to be relied upon. Within the constraints

and definitions outlined above the approach taken here did not make any comment or filter

the study for perceived quality instead accepted all studies as equal. However, studies were

divided between studies from within the UK and those based overseas and between studies

that reviewed others data from those presented their own original data. Results are

summarised in tables with the key to tables given below (Table 1).

Table 1. Key to results tables for each management/land-use

Symbol Meaning Cell shading Classification

Increase in the

magnitude of the

component

Original study

from within UK

Decrease in the

magnitude of the

component

Original study

from outside UK

Study found

both increase

and decrease

over time

Review article

No significant

effect for that

component

In order to summarise studies the number of studies with a definitive outcome were

counted no matter whether that outcome was positive or negative then the number of studies

that gave an improvement were counted. All the studies that gave a definitive result were then

classified to be an improvement or a worsening of the carbon budget where an improvement

was classed as an improved carbon storage and individual fluxes were considered solely as

Methodology

8

their magnitude and not their vector. In the case of the components considered by this study

we classified an improvement as: soil respiration = decreased; primary productivity =

increased; methane = decreased; DOC = decreased; POC = decreased; dissolved CO2 =

decreased; net ecosystem exchange = increased; and total carbon budget = increased. For

example, primary productivity is generally assessed relative to the atmosphere and given a

negative value, i.e. it is a vector quantity with both magnitude and direction, for this study its

magnitude only was considered and a positive result would be regarded as an increase in that

value .

Within this approach this means that each component for each management or land-

use can be given a proportion of success which in turn can be interpreted as probability of

improvement, e.g. 13 studies of soil respiration on drain-blocking showed a definitive result

of these 12 showed a decline in the magnitude of the soil respiration and so showed an

improvement as classified above, therefore, this approach would suggest that there is 92%

(12/13) chance that the next site where grip blocking is used would lead to an improvement

with to soil respiration. This calculation is then performed for each component for each

management/land-use. How then do we add the effect on the components together to get an

effect upon the total carbon budget? We propose a simple weight rule that is derived from the

stoichoimetry of the carbon budget of the Moor House site. For Moor House, Worrall et al.

(2009) have proposed the following equation for the stoichoimetry of the carbon budget:

RESPOCdisscoCHDOCRpp CCCCCCC 229442635100 24 (ii)

Where Cx = carbon from the following uptake or release pathways, where x is: pp = primary

productivity, R = net ecosystem respiration (referred to also as soil respiration), DOC =

dissolved organic carbon; CH4 = methane; dissco2 = dissolved CO2; POC = particulate

organic carbon; and RES = residual carbon stored in the soil.

Equation (ii) can be re-calculated as a series of weightings where the stoichoimetric

coefficients in equation (ii) are summed and then the weighting for each component is its

coefficient divided by the sum of the coefficients (e.g. for primary productivity = 100/178 =

0.56). Then in order to calculate the proportion of improvement for the carbon budget as a

whole as opposed to the proportion for any individual component is then the individual

proportions multiplied by the weighting (e.g.Table 2). The weighted proportion for the

carbon budget can be considered to be the probability that that particular management will be

bring a benefit to the carbon budget. Furthermore, equation (ii) can be re-interpreted in terms

of greenhouse gas potential (Equation (iii)) by multiplying the CH4 by 24 and allowing for

the proportion of DOC and POC that would be recycled to the atmosphere:

RESPOCdisscoCHDOCRpp CCCCCCC 2244961035100 24 (iii)

Methodology

9

Table 2. Example of the weighted proportion calculation for the case of afforestation.

Component Proportion from

Equation (ii)

Proportion for

GHG budget

Proportion from

afforestation

Weighted

proportion

Primary

productivity

100/178 100/248 11/11 0.56

Respiration 35/178 35/248 0/15 0

DOC 26/178 9/248 0/2 0

CH4 4/178 96/248 7/7 0.02

POC 9/178 4/248 1/1 0.05

Diss. CO2 4/178 4/248 0/0 0

Total 0.62

The same weighting procedure that enables the calculation of the overall success proportion

also means that an effective sample size can be calculated relative to both the carbon budget

and the greenhouse gas budget. The weighting relative to equations (ii) and (iii) can be used

to adjust the number of studies included in the review and the sum of these is then the relative

sample of the entire carbon or greenhouse gas budget. The weighting of studies according to

equation (ii) or (iii) shows that studies that consider primary productivity are more important

than those considering dissolved CO2.

This approach to combining evidence from multiple studies transfers data into a

probability and the approach here is in effect converting the proportions into a beta

distribution. All beta distributions can be described by two parameters (a, b) and these are

equivalent to a + b = total number of studies, and a = the number of studies showing an

improvement. Therefore, the characteristics of the beta distribution can be used to give an

uncertainty on the estimation of the probability of an improvement, the variance of a beta

distribution is:

12

Var (iv)

Equation (iv) is used to give an uncertainty estimate on the probability of improvement.

Finally, this whole approach is Bayesian and as such means this study has started with

an uninformative prior (a, b)=(0,0) and that as studies were considered we can recalculate the

Methodology

10

beta probability distribution and each new beta distribution as prior information for any new

studies. As each study is considered the understanding of the distribution is improved and

contrary information is easily identified and assessed.

2.2. Analysis of computer modelling results

In order to support the literature review all available results of the Durham Carbon Model

were examined in order to assess the impact of management upon the carbon budget of peat

soils. In order to make the assessment the data were sorted by the management types that can

be considered by the model (presence absence of: burning, grazing, drainage, bare soil or

forest plantation) and the predicted budgets were then assessed relative to these land

management factors using altitude as a covariate. On the basis of the significant differences

found linear models were constructed.

In total 4544 model runs were considered covering 1309 km2 grid squares of upland where

peat soil represented at least 10% of the soils in the grid square. The areas chosen covered the

Peak District, Lake District, the Forest of Bowland and the Water of Cree catchment.

Pristine

11

3. Pristine

Author: Soil

Respiration of

CO2 (tonnes

C/km2/yr)

Primary

productivity

(tonnes

C/km2.yr)

Methane (tonnes

C/km2/yr)

DOC (tonnes

C/km2/yr)

POC (tonnes

C/km2/yr)

Dissolved

CO2 (tonnes

C/km2/yr)

Net ecosystem

exchange (tonnes

C/km2/yr)

Total C budget (tonnes

C/km2/yr)

Byrne and Milne

(2006)

+50

Tucker (2003) -50 - -70

Cannell et al.

(1993)

+3 to +30 -40 to -70

Brainard et al.

(2003)

-40 - -70

Worrall et al

(2007)

+11 to 20

Cannell (1999) +3- -30 -20 to -50

Billett et al

(2004)

30 (±62) +0.5 -30 (±25)

Pristine

12

Orr et al (2008) -20 to -50

Hargreaves et

al. (2003)

-25

Dawson et al

(2004)

8.3 to 26.2 8.15 to 97 2.62 to

10.4

Worrall et al.

(2005)

+64.2 to

+94.9

9.6 to 25.6

: - 4.5

Lloyd et al.

(1998)

50.5

Clymo and

Pearce (1995)

31.1 to 32.5

Clymo and

Reddaway

(1971)

-134 to -254

Anderson

(2002)

-4.1 to -72.5

Pristine

13

Dawson et al

(2002)

83.5 to 169 18.5 to 27.4 2.62 to

8.75

Best and Jacobs

(1997)

+2

Van de Pol-Van

Dasselaar et al.

(1999)

+2.3 to +28

Worrall et al

(2003)

+7.1 9.4 to 15 2.7 to 31.3 3.8

-55

-15.4 +/-11.9

Worrall et al. (in

press)

49 to 58 -151 to -190 5.2 to 6.9 12.5 to -86 7 to 22.4 1 to 15.2 -20 to -91

Garnett et al.

(1998)

-117 to 341

MacDonald et

al. (1998)

0.2 to 13.5 t

Minkkinen et al

(2002)

-21

Pristine

14

Immirzi et al.

(1992)

-40 to -70

Korhola et al.

(1995)

-15 to 30

Alm et al. (1997) -18

Turunen et al.

(1999)

-17 to 26

Cleary et al.

(2005)

+4 -27 -10 to -35

Van den Bos

(2003)

+1 to + 57 - 50

Hendricks et al.

(2007)

-33

McNeil and

Waddington

(2003)

-12 to -23

Vasander (1982) -380

Glenn et al.

(1993)

-25

Pristine

15

Bubier et al

(2003)

-15 to -20

Bubier et al.

(1999)

-3 to 64

Suyker et al.

(1997)

-23

Gorham (1990)

-29

Glaser and

Janssens (1986)

-35

Ovenden (1990)

-10 to -35

Tolonen and

Turunen (1996)

+7.1 to 31.3

-2.8 to -88.6

Paavilainen and

Paivanen (1995)

+2-5

-5 to -120

Freibauer et al

(2004)

-10 to -3o + 16

Schlesinger

(1990)

- 2.4

Pristine

16

Nilsson et al

(2008)

+9 +/1 1.8

20.4+/- 2.1

6.0 +/- 0.8

-55 +/- 1.9

-27 +/- 3.1

Roulet et al

(2007)

+2.8 to +4.4

+14.9 (+/- 3.1) -2 to -112

-21.5 (+/- 39)

Pristine

17

3.1 Meta-analysis

The above data shows that in the overwhelming majority of cases pristine peat soils are net sinks of

carbon. Across all the managements and land uses there are very few studies that measure a

complete carbon budget for a peat soil and out of the 5 known to this study, 4 are for pristine cases

(Billet et al. 2004, Roulet et al. 2007, Nilsson et al.,2008, Worrall et al., 2009 as updating Worrall et

al. 2003, 2005). Worrall et al (2009) has proposed a simple stoichoimetry:

RESdisscoCHDOCRpp CCCCCC 31442635100 24

Where Cx = carbon from the following uptake or release pathways, where x is: pp = primary

productivity, R = net ecosystem respiration, DOC = dissolved organic carbon; CH4 = methane; dissco2

= dissolved CO2; and RES = residual carbon stored in the soil. At this scale, input from rainfall is

negligible. Further, POC losses are not included in this equation as POC losses are from the residual

carbon stored in the soil and so a further equation can be given:

RESPOCres CCC 22931

Where: CPOC = the carbon lost as particulate organic carbon. Similar, but incomplete stoichoimetries

have been proposed by Gorham (1990).

3.2 Modelling

The carbon budget of those grid squares within the modelling where there was no burning, grazing,

drainage, forestation or any other management intervention were collated. The carbon budget was

then regressed against the altitude of the grid square; the percentage peat cover, and the

percentage of bare soil. The resulting equation tells us about the expected carbon budget at any

altitude.

(i) r2 = 96%, n = 474

Where: Ctotal = the total carbon budget (tonnes C/km2/yr); A = altitude (m above sea level); fpeat = the

fraction of the grid square that is peat soil; and fbaresoil = the fraction of the grid square that is bare

soil. All variables are significant at least at the 95% level and r2 = 96%.

When there is 100% peat soil and no bare soil, then:

Pristine

18

(ii)

This means that the maximum C budget would be achieved at sea level and would be 136.8 tonnes

C/km2/yr and that the average lapse rate of 8.7 tonnes C/km2/yr/100 m. The range of A for the

regression is 109 to 550 m asl.

3.3 Gaps, assumptions and limitations

The study has only 4 complete studies but has to use models to consider effects of altitude and has no data upon which to consider effects of differing vegetation or peat types, e.g. how does a Calluna-dominated ecosystem differ from a sedge-dominated system?

3.4 Associated benefits or disbenefits

If we consider the pristine case as the one against which all other management and land-uses are

judged then we will consider the benefit and disbenefit of those actions under those headings.

3.5 Costs

The costs of actions are considered as the costs of restoring to pristine.

3.6 References:

Alm, J., Talanov, A., Saarnio, S., Silvola, J., Ikkonen, E., Aaltonen, H., Nykanen, H., and Marukainen,

P.J. (1997). Reconstruction of the carbon balance for microstites in a boreal oligotrophic pine fen,

Finald. Oecologia 111, 423-431.

Anderson, D.E (2002) Carbon accumulation and C/N ratios of peat bogs in North-West Scotland,

Scottish Geographical Journal 118:4, 323-341

Best EPH, Jacobs FHH. The influence of raised water table levels on carbon dioxide and methane production in ditch-dissected peat grasslands in the Netherlands. Ecol Engineering 1997; 8: 129-144. Brainard, J, Lovett, A and Bateman, I (2003) Social & Environmental Benefits of Forestry Phase 2:

Carbon sequestration benefits of woodland, Report to Forestry Commission Edinburgh

Billett, M.F, Palmer, S.M, Hope, D, Deacon, C, Storeton-West, R, Hargreaves, K.J, Flechard, C and

Fowler, D (2004) Linking land-atmosphere-stream carbon fluxes in a lowland peatland system, Global

Biogeochem. Cycles, 18,

Pristine

19

Bubier, J.L, Bhatia, G, Moore, T.R, Roulet, N.T and Lafleur, P.M (2003) Spatial and Temporal Variability in Growing-Season Net Ecosystem Carbon Dioxide Exchange at a Large Peatland in Ontario, Canada, Ecosystems 6: 353-367

Byrne, K.A and Milne, R (2006) Carbon stocks and sequestration in plantation forests in the Republic of Ireland, Forestry 79(4), 361-369

Cannell (1999) Growing Trees to Sequester Carbon in the UK: Answers to some common questions, Forestry 72:3, 237-247

Cannell, M.G.R, Dewar, R.C and Pyatt, D.G (1993) Conifer Plantations on Drained Peatlands in Britain: a Net Gain or Loss of Carbon? Forestry 66:4, 353-369

Cleary, J, Roulet, N.T and Moore, T.R (2005) Greenhouse Gas Emissions from Canadian Peat Extraction. 1990-2000: A Life-cycle Analysis, Ambio 34 (6), 456-461

Clymo, R.S., and Pearce, D.M.E., (1995). Methane and carbon dioxide production in transport through and efflux from a peatland. Philos. Trans. R. Soc. A. 350, 249-259.

Clymo RS, Reddaway EJF. Productivity of Sphagnum (bog-moss) and peat accumulation. Hidrobiologia 1971; 12: 181-192. Dawson, J.J.C, Billett, M.F, Hope, D, Palmer, S.M and Deacon, C.M (2004) Sources and sinks of aquatic carbon in a peatland stream continuum, Biogeochemistry 70: 71-92

Dawson, J.J.C, Billett, M.F, Neal, C and Hill, S (2002) A comparison of particulate, dissolved and gaseous carbon in two contrasting upland streams in the UK, Journal of Hydrology 257: 226-246

Freibauer, A, Rounsevell, M.D.A, Smith, P and Verhagen, J (2004) Carbon sequestration in the agricultural soils of Europe, Geoderma 122: 1-23

Glaser, P.H., Janssens, J.A., (1986). Raised bogs in eastern North America – transitions in landforms

and gross stratigraphy. Canadian Journal of Botany 64, 395-415.

Glenn, S, Heyes, A and Moore, T (1993) Carbon dioxide and methane emissions from drained

peatland soils, Southern Quebec, Global Biogeochemical Cycles 7, 247-258

Gorham, E (1990) Northern peatlands: Role in the carbon cycles and probable responses to climatic

warming, Ecological Applications 1 (2), 182-195

Hargreaves, K.J, Milne, R and Cannell, M.G.R (2003) Carbon balance of afforested peatland in

Scotland, Forestry 76: 3, 299-317

Hendricks, D.M.D, van Huissteden, J, Dolman, A.J and van der Molen, M.K (2007) The full greenhouse

gas balance of an abandoned peat meadow, Biogeosciences, 4, 411–424

Immirzi, C.P., Maltby, E., and Clymo, R.S. (1992). The Global Status of Peatlands and their role in

Carbon Cycling. Report for Friends of the Earth, London.

Lloyd, D., Thomas, K.I., Benstead, J., Davies, K.L., Lloyd, S.H., Arah, J.R.M., and Stephen, K.D., (1998).

Methanogenesis and CO2 exchange in an ombogotrophic peat bog. Atmos. Environment 32, 3229-

3238.

Pristine

20

McNeil, P and Waddington, J.M (2003) Moisture controls on Sphagnum growth and CO2 exchange

on a cutover bog, Journal of applied ecology 40: 354-367

Minkkinen, K, Korhonen, R, Savolainen, I and Laine, J (2002) Carbon balance and radiative forcing of

Finnish peatlands 1900-2100- the impact of forestry drainage, Global Change Biology 8: 785-799

Nilsson, M, Sagerfors, J, Buffam, I, Laudon, H, Eriksson, T, Grelle, A, Klemedtssons, L, Wesliens, P and

Lindroth, A (2008) Contemporary carbon accumulation in a boreal oligotrophic minerogenic mire- a

significant sink after accounting for all C-fluxes, Global Change Biology 14: 2317-2332

Orr, H.G, Wilby, R.L, McKenzie Hedger, M and Brown, I (2008) Climate change in the uplands: a UK

perspective on safeguarding regulatory ecosystem services, Climate Research 37: 77-98

Ovenden, L. (1990). Peat accumulation in northern wetlands. Quaternary Research 33, 377-386.

Paavilainen, E and Paivanen, J ((1995) Peatland Forestry: Ecology and Principles, Springer, 1-248

Roulet, N.T, Lafleurs, P.M, Richard, P.J.H, Moore, T.R, Humphreys, E.R and Bubier, J (2007)

Contemporary carbon balance and late Holocene accumulation in a northern peatland, Global

Change Biology 13: 397-411

Schlesinger, W.H (1990) Evidence from chronosequence studies for a low carbon storage potential of

soils, Nature 348: 232-234

Suyker, A.L., Verma, S.B., and Arkebauer, T.L., (1997). Season long measurement of carbon dioxide

exchange in a boreal fen. Jour. Geophys. Res., 102, 29021 – 29028.

Tolonen, K and Turunen, J (1996) Accumulation rates of carbon in mires in Finland and implications

for climate change, The Holocene, 6: 171-178

Tucker, G (2003) Review of the impacts of heather and grassland burning in the uplands on soils,

hydrology and biodiversity, English Nature, Research Reports 550:

Turunen, J., Tolonen K., Tolvanen, S., Remes, M., Ronkainen, J., and Jungner, H., (1999). Carbon

accumulation in the mineral subsoil of boreal mires. Global Biogeochemical Cycles 13, 71-79.

Van den Bos, R (2003) Restoration of former wetlands in the Netherlands; effect on the balance

between CO2 and CH4 source, Netherlands journal of Geosciences 82(4), 325-332

Van den Pol-Van Dasselaar A, Van Beusichem ML, Oenema O. Determinants of spatial variability of methane emissions from wet grasslands on peat soil. Biogeochemistry 1999; 44: 221-237. Vasander, H. (1982). Plant biomass and production in virgin, drained and fertilized sites in a raised

bog in southern Finland. Annales Botanic Fennici 19, 103-125.

Worrall, F, Burt, T and Adamson, J (2005) Fluxes of dissolved carbon dioxide and inorganic carbon

from an upland peat catchment: implications for soil respiration, Biogeochemistry 73: 515-539

Worrall, F, Reed, M, Warburton, J and Burt, T (2003) Carbon budget for a British upland peat

catchment, The Science of the Total Environment 312, 133-146

Pristine

21

Worrall, F., Burt, T.P., Adamson, J.K., Reed, M., Warburton, J., Armstrong, A., and M.Evans. 2007.

Predicting the future carbon budget of an upland peat catchment. Climatic Change, 85, 1-2.

Worrall, F., Burt, T.P., Rowson, J.G., Warburton, J., and J.K.Adamson. 2009. The Multi-annual carbon

budget of a peat-covered catchment. The Science of the Total Environment (in press).

Afforestation

22

4. Afforestation

Author: Soil Respiration of

CO2

Primary

productivity

Methane DOC POC Dissolved

CO2

Net

ecosystem

exchange

Total C

budget

Byrne and Milne

(2006)

Byrne and Farrell

(2005)

Holden et al

(2007)

Cannell et al.

(1993)

Cannell (1999)

Burt et al. (1983)

Afforestation

23

Hargreaves et al.

(2003)

:

Neal et al (2001)

Anderson (2002)

Brainard et al.

(2003)

Minkkinen et al

(2007)

Minkkinen et al

(2002)

Vompersky et al

(1992)

Makiranta et al

(2009)

Afforestation

24

Alm et al (1999)

Domisch et al

(1998)

Gorham (1990) :

Armentano and

Menges (1986)

Tolonen and

Turunen (1996)

Jandl et al (2007)

No of studies 15 11 7 2 1 0 6 4

No. with

improvement 0 11 7 0 1 0 5 4

Afforestation

25

4.1 Meta-analysis

The majority studies show that size of the carbon sink would increase upon the planting of trees, but

the literature suggests that there is a transfer in carbon storage from the peat soils to the

aboveground biomass. The majority of studies show an increase in primary productivity; and

increased losses of carbon via soil respiration of CO2 and DOC with declines in CH4 flux. The transfer

of carbon sink from soil to aboveground biomass does mean that the longevity of carbon stores will

be limited to the growth phase of the trees. The meta-analysis suggests that the probability of

improved carbon budget is 63% but 81% for improved greenhouse gas budgets. Although these

studies consider the increase in primary productivity with afforestation these studies do not

consider the role of product substitution as means of creating an ongoing sink of carbon. If the

planted forest is harvested at the end of its optimal growth stage, the forest is replanted and then

the harvested product is substituted for another product whose production would have involved

production of greenhouse gases then substantial carbon benefits can be achieved. Furthermore,

afforestation would achieve greater carbon benefits if the peat soil was left intact and the equivalent

number of trees planted in mineral soils.

4.2 Modelling

In this case modelling considered the biomass separately. In a study of the Galloway forest the

average change due to forest of the C export from peat soil was 194 tonnes C/km2/yr (-59 tonnes

C/km2/yr for pristine peat in the area compared to 134 tonnes C/km2/yr), i.e. planting of coniferous

forest causes a transition from small C sink to large C source with respect to the soil. The carbon

stored in the trees is critically dependent upon age and growth rates of trees will vary. Again using

data from the Galloway forest it is possible to see that the maximum carbon sink will exist for this

setting between 20 and 70 years (Figure 1), but after 80 years the forest biomass is mature. For the

Galloway case where the forest biomass is included and given the stand age distribution of this

particular forest area shows that the carbon budget has risen from an average of -59 tonnes

C/km2/yr to -253 tonnes C/km2/yr, but it should be reiterated that this advantage would reduce with

time. These calculations do not include the possibility of product substitution. In the case of the

Galloway forest example used here then we would suggest harvesting at a stand age of 70 years old,

replanting and use of the harvested wood. It is not possible to use Figure 1 to assess the magnitude

of the carbon gain in the case of product substitution as this curve gives biomass but not yield.

However, it should be pointed out that the benefits of a product substitution scheme can be

achieved without the trees being planted upon peat soils and could be achieved on minerals soils

while the peat soil is left pristine to act as a carbon and greenhouse sink in its own right.

Afforestation

26

Figure 1. The aboveground biomass of plantation forest in Galloway over the growth of the trees.


No complete budgets are available let alone any complete budget that compares before and after planting.

Information for growth rates and stand age biomass distributions for different regions of the country are available from Forest Research.


The impact of afforestation on the wider environment are well researched and reviewed in: Holden

et al. (2007), Ryenolds (2007), Mount et al. (2005), Warren (2000), and Gray et al. (1999) . Large-

scale afforestation has been associated with stream acidification and consequent loss of steam

biodiversity, but equally, there is a loss of biodiversity in the afforested area especially as this study

considers afforestation is coniferous plantation. The co-benefit of afforestation is that trees do

represent a commercial product and the use of the harvested wood in a product substitution

scheme represents the greatest possible carbon storage.

4.5 Costs

The cost of afforerstation per area is unknown.

4.6 References:

Afforestation

27

Alm, J, Schulman, L, Walden, J, Nykanen, H, Martikainen, P.J and Silvola, J (1999) Carbon balance of a

boreal bog during a year with an exceptionally dry summer, Ecology 80 (1), 161-174



Armentano, T.V., and Menges, E.S., (1986) Patterns of change in the carbon balance of organic soil-

wetlands of the temperate zone. Jounral of Ecology 74 , 755-774.

Brainard, J, Lovett, A and Bateman, I (2003) Social & Environmental Benefits of Forestry Phase 2:

Carbon sequestration benefits of woodland, Report to Forestry Commission Edinburgh

Burt, T.P, Donohoe, M.A and Vann, A.R (1983) The effect of forestry drainage operations on upland

sediment yields: The results of a storm based study, Earth Surface Processes and Landforms 8: 339-

346

Byrne, K.A and Farrell, E.P (2005) The effect of afforestation on soil carbon dioxide emissions in

blanket peatland in Ireland, Forestry, 78: 217 – 227

Byrne, K.A and Milne, R (2006) Carbon stocks and sequestration in plantation forests in the Republic

of Ireland, Forestry 79(4), 361-369

Cannell (1999) Growing Trees to Sequester Carbon in the UK: Answers to some common questions,

Forestry 72:3, 237-247

Cannell, M.G.R, Dewar, R.C and Pyatt, D.G (1993) Conifer Plantations on Drained Peatlands in Britain:

a Net Gain or Loss of Carbon? Forestry 66:4, 353-369

Domisch, T, Finer, L, Karsisto, M , Laiho, R and Laine, J (1998) Relocation of carbon from decaying

litter in drained peat soils, Soil Biol. Biochem 30:12, 1529-1536

Gorham, E (1990) Northern peatlands: Role in the carbon cycles and probable responses to climatic

warming, Ecological Applications 1 (2), 182-195

Gray, IM; Edwards-Jones, G. (1999). A review of the quality of environmental impact assessments in

the Scottish forest sector. Forestry 72 (1): 1-10.

Hargreaves, K.J, Milne, R and Cannell, M.G.R (2003) Carbon balance of afforested peatland in

Scotland, Forestry 76: 3, 299-317

Holden, J, Shotbolt, L, Bonn, A, Burt, T.P, Chapman, P.J, Dougill, A.J, Fraser, E.D.G, Hubacek, K, Irvine,

B, Kirkby, M.J, Reed, M.S, Prell, C, Stagl, S, Stringer, L.C, Turner, A and Worrall, F (2007)

Environmental change in moorland landscapes, Earth-Science Reviews 82: 75-100

Jandl, R, Lindner, M, Vesterdahl, L, Bauwens, B, Baritz, R, Hagedorn, F, Johson, D.W, Minkkinen, K,

Byrne, K.A (2007) How strongly can forest management influence soil carbon sequestration,

Geoderma 137: 253-268

http://apps.isiknowledge.com/InboundService.do?SID=R2GMg1AGkHp@4fPgAB@&uml_return_url=http%3A%2F%2Fpcs.isiknowledge.com%2Fuml%2Fuml_view.cgi%3Fproduct_sid%3DR2GMg1AGkHp%404fPgAB%40%26product%3DWOS%26marklist_id%3DWOS%26database_id%3DGB%26product_st_thomas%3Dhttp%253A%252F%252Festi%252Eisiknowledge%252Ecom%253A8360%252Festi%252Fxrpc%26sort_opt%3DDate&action=retrieve&product=WOS&mode=FullRecord&viewType=fullRecord&frmUML=1&UT=000078692300001

http://apps.isiknowledge.com/InboundService.do?SID=R2GMg1AGkHp@4fPgAB@&uml_return_url=http%3A%2F%2Fpcs.isiknowledge.com%2Fuml%2Fuml_view.cgi%3Fproduct_sid%3DR2GMg1AGkHp%404fPgAB%40%26product%3DWOS%26marklist_id%3DWOS%26database_id%3DGB%26product_st_thomas%3Dhttp%253A%252F%252Festi%252Eisiknowledge%252Ecom%253A8360%252Festi%252Fxrpc%26sort_opt%3DDate&action=retrieve&product=WOS&mode=FullRecord&viewType=fullRecord&frmUML=1&UT=000078692300001

Afforestation

28

Makiranta, P, Laiho, R, Fritze, H, Hytonen, J, Laine, J and Minkkinen, K (2009) Indirect regulation of

heterotrophic peat soil respiration by water level via microbial community structure and

temperature sensitivity, Soil Biology and Biogeochemistry , doi: 10.1016/j.soilbio.2009.01.004

Minkkinen, K, Laine, J, Shurpali, N.J, Makiranta, P, Alm, J and Penttila, T (2007) Heterotrophic soil

respiration in forestry drained peatlands, Boreal Environment Research 12, 115-126

Minkkinen, K, Korhonen, R, Savolainen, I and Laine, J (2002) Carbon balance and radiative forcing of Finnish peatlands 1900-2100-the impact of forestry drainage, Global Change Biology 8: 785-799

Mount, NJ; Smith, GHS; Stott, TA. (2005). An assessment of the impact of upland afforestation on lowland river reaches: the Afon Trannon, mid-Wales. Geomorphology 64 (3-4): 255-269. Neal, C, Reynolds, B, Neal, M, Pugh, B, Hill, I and Wickham, H (2001) Long-term changes in the water quality of rainfall, cloud water and stream water for the moorland, forested and clearfelled catchments at Plynlimon, mid Wales, Hydrology and Earth System Science 5: 459-476 Reynolds, B. (2007) Implications of changing from grazed or semi-natural vegetation to forestry for carbon stores and fluxes in upland organo-mineral soils in the UK. Hydrology and Earth System Science11 (1): 61-76. Tolonen, K and Turunen, J (1996) Accumulation rates of carbon in mires in Finland and implications for climate change, The Holocene, 6: 171-178

Tolonen, K., and Turunen, J (1996) Accumulation rates of carbon in mires in Finland and implications for climate change. Holocene 6,:171-178

Vompersky, S.E, Smagina, M.V, Ivanov, A.I and Glukhova, T.V (1992) The effect of forest drainage on

the balance of organic matter in forest mires, in: Bragg, O.M, Hulme, P.D, Ingram, H.A.P and

Robertson, R.A (eds) Peatland Ecosystems and Man: An Impact Assessment, Department of

Biological Sciences, University of Dundee, UK, 17-22.

Warren, C (2000) Birds, bogs and forestry revisited: The significance of the Flow Country controversy. Scottish Geographical Journal 116 (4): 315-337.

Burning

29

5. Managed burning


CO2

Primary

productivity


CO2

Net ecosystem

exchange

Total C

budget

Dawson and

Smith (2007)

Ward et al

(2007)

Rein et al.

(2009)

.

Worrall et al.

(2007)

Ball (1974)

Tucker (2003)

Garnett et al.

(2000)

Burning

30

Clay, Worrall

and Fraser

(2009)

Imeson (1971)

Tallis (1987)

Mitchell and

McDonald

(1995)

Tan et al (2007)

Dikici and

Yilmaz (2006)

Wieder et al

(2007)

Burning

31

Limpens et al

(2008)

Kauppi, and

Tomppo (1993)

No. of studies 5 7 1 3 3 1 1 4

No. with

improvement 0 0 1 1 0 0 0 0

Burning

32

5.1 Meta-analysis

We should distinguish between the burn itself and the consequences of the burn. The burn itself

could disturb three possible reserves of carbon: the above ground vegetation, the litter layer; and

the soil and belowground biomass. All burning releases carbon to the atmosphere but “cool” burns

release only from the quick cycling vegetation reservoir and produces char which is a transfer of

refractory carbon to the litter and soil reserves. A “hot” burn will release carbon from litter and soil

layers, i.e. from slow cycling reserves. The balance of these is not known. Between burns we

discover that soil respiration increases, primary productivity has decreased though growth rates

maybe large. Methane fluxes decreased even though water tables are seen to rise upon burning:

DOC concentrations show no significant changes. We have few published studies of POC or dissolved

CO2. There is at present no study of a complete suite of carbon fluxes, but Garnett et al (2001)

measured peat depth accumulation and showed a loss of carbon equivalent to 75 gC/m2/yr for 10

year burning. The meta-analysis suggests there is only a 7% probability of burning improving the

carbon budget and a 40% chance of improving the greenhouse gas balance largely because the

observations of Ward et al. (2007) that methane fluxe decreased upon burning. There are no studies

of cessation of burning and the cessation of burning has to be assumed to be the opposite of

burning, i.e. there would be 93% chance of carbon budget benefit from cessation of managed

burning and a 60% chance of greenhouse gas benefit.

5.2 Modelling

The presence of burning decrease the carbon sequestration by an average of 83.4 tonnes C/km2/yr.

Burning has significant if small interactions with both grazing and drainage, with respect to grazing

when there is no grazing the effect burning increases to 89.4 tonnes C/km2/yr. When draining is

present the effect of burning increases to 93 tonnes C/km2/yr. This first approach to modelling does

not include the changes in stocks of carbon at the time of the burn. The fire, be it perscribed or

uncontrolled, there will be a loss of biomass at the time of the fire perhaps accompanied by the loss

of carbon from litter from peat layers itself. An accumulation model comparing an unburnt, Calluna-

dominated peat soil with a the same ecosystem burnt at frequencies between 5 and 25 years shows

that if the burn is “cool” then it is possible that burning could increase carbon stocks even if peat

accumulation decreased.


No complete budgets are available for any managed or wild-fire and no analysis of carbon stock changes across a fire exist and we cannot parameterise our stocks model for any fire of any type.

Wildfire and managed burning are not distinguished here.

Degrees of wildfire and managed burning are not discussed. Degrees of burning could be the nature of the burn – “hot” vs. “cool” or the frequency of burn. The modelling here assumes a burn frequency of between 10 and 20 years.

Burning

33


Managed burning of upland environments is undertaken for a number of reasons, these include:

increased grazing and grouse productivity; and decreased probability of wildfires. This vegetation

response to burning improves grazing for sheep and is reflected in higher sheep performance on

burnt plots (Lance, 1983) and grouse production has also been correlated with the density of burnt

areas (Picozzi, 1968). However, there is little or no scientific evidence to support the contention that

managed burning prevents wildfire. The effect of burning on water quantity is argued over in

literature with the most direct and robust evidence suggesting no significant difference or change

between burnt and unburnt areas or upon burning. In terms of water quantity burnt areas do show

decreased depths to the water table and increased frequency of surface runoff. Burning tends to

break up areas of heather (Calluna vulgaris) and increase biodiversity in areas of heather dominance,

however, heather dominance is also a possible product of managed burning. Evidence from the Hard

Hill plots within the Moor House National Nature Reserve suggests that upon cessation of burning

heather comes to dominate, and so if burning is to cease it may also be considered beneficial to

actively revegetate. The timescale of benefits of cessation could be considered to be the life cycle of

heather which in the North Pennines is measured as 25 years (Forrest, 1971) but maybe shorter

further south in England.

5.5 Costs

The nearest equivalent cost is for mowing which is £12800 to £20000 /km2, but for cessation of

burning rather than the cost of burning there must be a saving.

5.6 References:

Ball, M.E., 1974. Floristic changes on grasslands and heaths on the Isle of Rhum after a reduction or

exclusion of grazing. Journal of Environmental Management 2, 299-318.

Clay, G.D., Worrall, F., Fraser, E.D., Effects of managed burning upon Dissolved Organic Carbon (DOC)

in soil water and runoff water following a managed burn of a UK blanket bog, Journal of Hydrology

(2009), doi: 10.1016/j.jhydrol.2008.12.022

Dawson, J.C and Smith, P (2007) Carbon losses from soil and its consequences for landuse

management, Science of the total environment 382: 165-190

Dikici, H and Yilmaz, C.H (2006) Peat fire effects of some properties of an Artificially Drained

Peatland, Journal of Environmental Quality 35: 866-870

Forrest, G.I. (1971) Structure and production of North Pennine blanket bog vegetation. Journal of Ecology, 59 (2), 453-479. Garnett, M.H., Ineson, P. and Stevenson, A.C., 2000. Effects of burning and grazing on carbon sequestration in a Pennine blanket bog, UK. Holocene, 10(6): 729-736

Burning

34

Imeson, A.C (1971) Heather burning and soil erosion on North Yorkshire Moors, Journal of Applied

Ecology 8, 537-548

Kauppi, P.E and Tomppo, E (1993) Impact of forests on net national emissions of Carbon Dioxide in

West Europe, Water, Air and Soil Pollution 70: 187-196

Lance, A.N., 1983. Performance of Sheep on Unburned and Serially Burned Blanket Bog in Western

Ireland. Journal of Applied Ecology, 20(3), 767-775.

Limpens, J, Berendse, F, Blodau, C, Canadell, J.G, Freeman, C, Holden, J, Roulet,N Rydin, H and

Schaepman-Strub (2008) Peatlands and the carbon cycle: from local processes to global implications-

a synthesis, Biogeosciences 5: 1475-1491

Mitchell, G and McDonald, A.T (1995) Catchment Characterization as a Tool for Upland Water

Quality Management, Journal of Environmental Management 44, 83-95

Picozzi, N., 1968. Grouse Bags in Relation to Management and Geology of Heather Moors Journal of

Applied Ecology, 5(2), 483-488.

Rein, G, Cohen, S and Simeoni, A (2009) Carbon emissions from smouldering peat in shallow and

strong fronts, Proceedings of the combustion institute (2009) doi: 10.1016/j.proci.2008.07.008

Tallis, J.H (1987) Fire and Flood at Holme Moss: Erosion processes in an upland blanket mire, The

Journal of Ecology 75:4 1099-1129

Tan, Z, Tieszen, L.L, Zhu, Z, Liu, S and Howard, S.M (2007) An estimate of carbon emissions from

2004 wildfires across Alaskan Yukon River Basin, Carbon Balance and Management 2: 12

Tucker, G (2003) Review of the impacts of heather and grassland burning in the uplands on soils,

hydrology and biodiversity, English Nature, Research Reports 550

Ward, S.E, Bardgett, R.D, McNamara, N.P, Adamson, J.K and Ostle, N.J (2007) Long-term

Consequences of Grazing and Burning on Northern Peatland Carbon Dynamics, Ecosystems 10: 1069-

1083

Wieder, R.K, Scott, K.D, Vile, M.A, Kamminga, K and Vitt, D.H (2007) Burning Bogs and Changing

Climate: Will Peatland Carbon Sinks become Sources? In: Robroek, B, Schaepman-Strub, G, Limpens,

J, Berendse, F and Breeuwer, A (Eds) (2007) Proceedings of the First International Symposium on

Carbon in peatlands, 15-18th April 2007, Wageningen, The Netherlands, 141pp, Wageningen

University, Wageningen, NL.

Worrall, F, Armstrong, A and Adamson, J.K (2007) The effects of burning and sheep-grazing on water

table depth and soil water quality in a upland peat, Journal of Hydrology 339: 1-14.

Deforestation

35

6. Deforestation

Author: Soil Respiration of CO2 Primary

productivity


CO2

Net

ecosystem

exchange

Total C

budget

Byrne and Farrell

(2005)

Neal et al (1998)

Neal et al (2001)

Glatzel et al

(2003)

Nieminen (2004)

No. of samples 1 4

Deforestation

36

No. With

improvement 1 0

Deforestation

37

6.1 Meta-analysis

There is a severe lack of direct evidence for the carbon budget changes upon deforestation. The

studies suggest a decline in soil respiration and in DOC release which is the reverse of that observed

for afforestation. Therefore, we could expect decreases in primary productivity, increases in

methane and POC fluxes. Deforestation would lead to bare soil and the fluxes at this time would be

critically dependent upon, the amount of forest biomass left behind; the time for revegetation to

occur; and the amount of disturbance due to harvesting. The meta-analysis suggests that the

probability of improved carbon budget is 19% with only 14% chance of improved greenhouse gas

budget.

6.2 Modelling

Given the biomass curve above (Figure 1) the loss of primary productivity can be predicted and there

would be an optimum harvest time which in the case shown in Figure 1 would be at 80 years of age.

The presence of bare soil and the role of revegetation are discussed later. But deforestion may form

part of a product substitution programme and so if the deforestation occurred at the optimal growth

stage (e.g. 70 years old – Figure 1), there was replanting and the products then used to substitute for

greenhouse gas producing products then deforestation, like afforestation, could show carbon

benefit. However, it should be reiterated that the carbon benefits of forestation, including

deforestation, can be achieved on minerals soils. As an alternative, we could propose that if

deforestation could occur at optimal growth stage, that the harvested wood is used for product

substitution; that the harvested area is restored with revegetation and perhaps blocking of drainage;

and that the harvested trees are replaced but planted on mineral soils then the carbon benefits may

be maximised.


We have assumed that deforestation is of coniferous plantation rather than of semi-natural and/or deciduous forest.

No complete budgets are available for any deforested site, but there is even a lack of component studies for deforestation.

We have not considered the use of the harvested timber in our carbon budgets.

The yield upon harvesting could be known from Forest Research data.


The benefit of deforestation is in the realisation of the timber crop. If there is a plan for product

substitution then there is a potential for long term and significant carbon storage. However, the

potential is greater for plantation if the plantation is on mineral rather than peat soil because on a

mineral soil there would be less loss from the soil carbon reservoir.

Deforestation

38

6.5 Costs

The cost of harvesting is offset by the price of the timber harvested depending upon the type and

end user of the timber.

6.6 References:

Byrne, K.A and Farrell, E.P (2005) The effect of afforestation on soil carbon dioxide emissions in

blanket peatland in Ireland, Forestry, 78: 217 – 227

Glatzel, S, Kalbitz, K, Dalva, M and Moore, T (2003) Dissolved organic matter properties and their

relationship to carbon dioxide efflux from restored peat bogs, Geoderma 113, 397-411

Neal, C, Reynolds, B, Neal, M, Pugh, B, Hill, I and Wickham, H (2001) Long-term changes in the water

quality of rainfall, cloud water and stream water for the moorland, forested and clearfelled

catchments at Plynlimon, mid Wales, Hydrology and Earth System Science 5: 459-476

Neal, C, Reynolds, B, Wilkinson, J, Hill, T, Neal, M, Hill, S and Harrow, M (1998) The impacts of conifer

harvesting on runoff water quality: a regional survey for Wales, Hydrology and Earth System

Sciences, 2 (2-3), 323-344

Nieminen, M. (2004) Export of dissolved organic carbon, nitrogen and phosphorus following clear-

cutting of three Norway spruce forests growing on drained peatlands in southern Finland. Silva

Fennica 38(2): 123–132.

Drainage

39

7. Drainage


productivity


CO2

Net ecosystem

exchange

Total C

budget

Byrne and

Milne (2006)

Holden et al

(2007)

Lloyd (2006)

Hughes et al.

(1999)

Holden (2005)

Cannell, Dewar

and Pyatt

(1993)

Clymo (1992)

Drainage

40

Orr et al. (2008)

Mitchell and

McDonald

(1995)

MacDonald et

al. (1998)

Dawson et al.

(2002)

Limpens et al

(2008)

Roulet et al.

(2007)

Laine et al.

(2007)

Minkkinen et al

(2002)

Dirks, Hensen

and Goudriaan

(2000)

Jauhiainen et al

(2005)

Drainage

41

Moore (2002)

Breeuwer et al

(2008)

McNeil and

Waddington

(2003)

Bubier (1995)

Christensen et

al. (1995)

Silvola et al. (?)

Updegraff et al.

(2001)

Oechel et al.

(1998)

Lafleur et al.

(2005)

Parmentier et

al (2008)

Drainage

42

Waddington et

al (2007)

Conlin et al

(2007)

Hendricks et al

(2007)

Jaatinen et al

(2007)

Vompersky et

al (1992)

Makiranta et

al. (2009)

Roulet et al.

(2003)

Glenn et al.

(1993)

Funk et al.

(1994)

Freibauer et al.

(2004)

Drainage

43

Byrne et al.

(2004)

Alm et al.

(1999)

Jones and

Mulholland

(1998)

Bubier et al.

(2003)

No. of samples 27 10 17 5 1 1 5

No. with

improvement 0 2 16 1 0 1 0

Drainage

44

7.1 Meta-analysis

The above table suggests that soil respiration would increase and methane would decrease, but

information upon DOC and primary productivity are presently equivocal. No studies have given

complete budgets of drained sites. The meta-analysis suggests that there is only a 19% chance of

carbon budget improvement and a 46% chance of greenhouse gas budget improvement.

7.2 Modelling results

The presence of drainage decreases the carbon budget by -4.8 tonnes C/km2/yr. When grazing is

present the effect of drainage is 10.1 tonnes C/km2/yr, when it its not present the effect is -0.6

tonnes C/km2/yr, i.e. when there is no grazing drainage could slightly improve carbon budgets. When

burning is present then the effect of drainage is 15.3 tonnes C/km2/yr while when it is not present

the effect of drainage is -5.8 tonnes C/km2/yr, i.e. drainage may slightly increase C budget when

burning is not present. In terms of the equivalent greenhouse gas budget drainage would be

expected to decrease the budget due to the declines in methane emissions and modelling suggests

that drainage of a pristine peat soils would decrease equivalent CO2 emissions by 19 tonnes CO2

equivalent/km2/yr.


No complete budgets are available

Degrees of drainage are not considered here

Modelling does not consider transitionary sinks, i.e. the loss of peat from the digging.


The reasons for draining are commonly stated as being for the lowering of water tables in order to

improve grazing, hunting or develop forestry (Ratcliffe and Oswald, 1988). However, Stewart and

Lance (1993) have shown that there is no evidence for any of the claims made for it. The effects

upon runoff have been reviewed by Holden et al. (2004).

7.5 Costs

Drainage is an uncommon component of restoration work and so was only considered by one

project within the Peat Compendium where cost were given as £3000 /km of drain if no equipment

had to be contracted in. This cost is very similar to that given for grip- and gully-blocking.

7.6 References:

Drainage

45



Breeuwer, A, Robroek, B.J.M, Limpens, J, Heijmans, M.M.P.D, Schouten, M.G.C and Berendse, F

(2008) Decrease summer water table depth affects peatland vegetation, Basic and Applied Ecology

(2008), doi:10.1016/j.baae.2008.05.005, 1-10

Bubier, J.L, Bhatia, G, Moore, T.R, Roulet, N.T and Lafleur, P.M (2003) Spatial and Temporal

Variability in Growing-Season Net Ecosystem Carbon Dioxide Exchange at a Large Peatland in

Ontario, Canada, Ecosystems 6: 353-367

Byrne, K.A and Milne, R (2006) Carbon stocks and sequestration in plantation forests in the Republic

of Ireland, Forestry 79(4), 361-369

Cannell, M.G.R, Dewar, R.C and Pyatt, D.G (1993) Conifer Plantations on Drained Peatlands in Britain:

a Net Gain or Loss of Carbon? Forestry 66:4, 353-369

Clymo, R.S (1992) Productivity and decomposition of peatland ecosystems, in: Bragg, O.M, Hulme,

P.D, Ingram, H.A.P and Robertson, R.A (eds) Peatland Ecosystems and Man: An Impact Assessment,

Department of Biological Sciences, University of Dundee, UK, 3-15

Conlin, M, Turetsky, M, Harden, J and McGuire, D (2007) Soil climate controls on C cycling in an

Alaskan fen: responses to water table mediated by vegetation, in: Robroek, B, Schaepman-Strub, G,

Limpens, J, Berendse, F and Breeuwer, A (Eds) (2007) Proceedings of the First International

Symposium on Carbon in peatlands, 15-18th April 2007, Wageningen, The Netherlands, 141pp,

Wageningen University, Wageningen, NL.

Dawson, J.J.C, Billett, M.F, Neal, C and Hill, S (2002) A comparison of particulate, dissolved and

gaseous carbon in two contrasting upland streams in the UK, Journal of Hydrology 257: 226-246

Dirks, B.O.M, Hensen, A and Goudriaan, J (2000) Effect of drainage on CO2 exchange patterns in an

intensively managed peat pasture, Climate Research 14: 57-63

Freibauer, A, Rounsevell, M.D.A, Smith, P and Verhagen, J (2004) Carbon sequestration in the

agricultural soils of Europe, Geoderma 122: 1-23

Funk, D.W, Pulman, E.R, Peterson, K.M, Crill, P.M and Billings, W.D (1994) Influence of water table

on carbon dioxide, carbon monoxide and methane fluxes from taiga bog microcosms, Global

Biogeochemical Cycles, 8, 271-278

Glenn, S, Heyes, A and Moore, T (1993) Carbon dioxide and methane emissions from drained

peatland soils, Southern Quebec, Global Biogeochemical Cycles 7, 247-258



Holden J. Chapman PJ. Labadz JC. 2004. Artificial drainage of peatlands: hydrological and

hydrochemical process and wetland restoration. Progress in Physical Geography 28: 95-123.

Drainage

46




Holden, J (2005) Peatland hydrology and carbon release: why small scale process matters,

Philosophical Transactions of the Royal Society A, 2891-2913

Hughes, S; Dowrick, DJ; Freeman, C, et al. (1999) Methane emissions from a gully mire in mid-Wales,

UK under consecutive summer water table drawdown. Environmental Science and Technology 33,

362-365.

Jaatinen, K, Laiho, R, Minkkinen, K, Pennanen, T, Penttila, T and Fritze, H (2007) Microbial

communities and soil respiration along a water-level gradient in a northern boreal fen, in: Robroek,

B, Schaepman-Strub, G, Limpens, J, Berendse, F and Breeuwer, A (Eds) (2007) Proceedings of the

First International Symposium on Carbon in peatlands, 15-18th April 2007, Wageningen, The

Netherlands, 141pp, Wageningen University, Wageningen, NL.

Jauhiainen, J, Takahas, H, Heikkinen, J.E.P, Martikainenz, P.J and Vasanders, H (2005) Carbon fluxes

from a tropical peat swamp forest floor, Global Change Biology 11, 1788-1797

Jones, J.B. Jr and Mulholland, P.J (1998) Carbon Dioxide Variation in a Hardwood Forest Stream: An

Integrative Measure of Whole Catchment Soil Respiration, Ecosystems 1: 193-196

Laine, A; Wilson, D; Kiely, G, et al. (2007) Methane flux dynamics in an Irish lowland blanket bog.

Plant and Soil 299, 181-193.




Lloyd, C.R (2006) Annual carbon balance of a managed wetland meadow in the Somerset Levels, UK,

Agricultural and Forest Meteorology 138:1-4, 168-179

Makiranta, P, Laiho, R, Fritze, H, Hytonen, J, Laine, J and Minkkinen, K (2009) Indirect regulation of

heterotrophic peat soil respiration by water level via microbial community structure and

temperature sensitivity, Soil Biology and Biogeochemistry , doi: 10.1016/j.soilbio.2009.01.004



Minkkinen, K, Korhonen, R, Savolainen, I and Laine, J (2002) Carbon balance and radiative forcing of

Finnish peatlands 1900-2100-the impact of forestry drainage, Global Change Biology 8: 785-799

Macdonald, J.A, Fowler, D, Hargreaves, K.J, Skiba, U, Leith, I.D and Murray, M.B (1998) Methane

emission rates from a northern wetland; Response to temperature, water table and transport,

Atmospheric Environment 32: 19, 3219-3227

Drainage

47

Mitchell, G and McDonald, A.T (1995) Catchment Characterization as a Tool for Upland Water

Quality Management, Journal of Environmental Management 44, 83-95

Moore, P.D (2002) The future if cool temperate bogs, Environmental Conservation 29:1, 3-20

Oechel, WC; Vourlitis, GL; Hastings, SJ, et al. (1998) The effects of water table manipulation and

elevated temperature on the net CO2 flux of wet sedge tundra ecosystems. Global Change Biology 4,

77-90.



Parmentier, F.J.W, Van der Molen, M.K, de Jeu, R.A.M, Hendricks, D.M.D and Dolman, A.J (2008) CO2

fluxes and evaporation on a peatland in the Netherlands appear not affected by water table

fluctuations, Agricultural and forest meterology (2008), doi:10.1016/j.agrformet.2008.11.007

Roulet, N.T, Ash, R, Quinton, W, Moore, T.R, Methane flux from drained northern peatlands: effect

of a persistent water table lowering on flux, Global Biogeochemical Cycles 7: 749-769

Roulet, NT; Lafleur, PM; Richard, PJH, et al. (2007) Contemporary carbon balance and late Holocene

carbon accumulation in a northern peatland. Global Change Biology 13, 397-411.

Vompersky, S.E, Smagina, M.V, Ivanov, A.I and Glukhova, T.V (1992) The effect of forest drainage on

the balance of organic matter in forest mires, in: Bragg, O.M, Hulme, P.D, Ingram, H.A.P and

Robertson, R.A (eds) Peatland Ecosystems and Man: An Impact Assessment, Department of

Biological Sciences, University of Dundee, UK, 17-22

Waddington, J, Strack, M, Tuitilla, E-S, Whittington, P, St-Arnaud, C, Rochefort, L, Bourbonniere, R

and Price, J (2007) The effects of water table draw-down on peatland hydrology, vegetation and

carbon dynamics, in: Robroek, B, Schaepman-Strub, G, Limpens, J, Berendse, F and Breeuwer, A (Eds)

(2007) Proceedings of the First International Symposium on Carbon in peatlands, 15-18th April 2007,

Wageningen, The Netherlands, 141pp, Wageningen University, Wageningen, NL

Drain-blocking

48

8. Drain-blocking


productivity


CO2

Net ecosystem

exchange

Total C

budget

Holden et al

(2007)

Lloyd (2006)

Worrall et al.

(2007a)

Worrall et al.

(2007b)

Worrall et al

(2003)

Gibson et al. (in

press)

MacDonald et

al. (1998)

Dawson et al.

(2002)

Drain-blocking

49

Holden (2005)

Orr et al. (2008)

Nieveen et al.

(2005)

Updegraff et al.

(2001)

Komulainen et

al. (1999)

Tuittila et al.

(2000)

Bubier et al.

(1993)

Bridgham et al.

(1991)

Berglund et al.

(2007)

Best and Jacobs

(1997)

Drain-blocking

50

Moore (2002)

Van den Bos

(2003)

McNeil and

Waddington

(2003)

LaFleur et al.

(2005)

Christensen et

al. (1995)

Parmentier et

al (2008)

Diamond and

Middleton

(2007)

Sallantaus

(2007)

Vasander et al

(2003)

Drain-blocking

51

Conlin et al

(2007)

Veenedndaal et

al (2007)

Hendricks et al

(2007)

Chojnicki et al.

(2007)

Petrone et al

(2001)

Alm et al.

(1999)

Jones and

Mulholland

(1998)

No of studies 19 9 12 7 2 3 0 4

No. with

improvement 11 5 0 4 1 2 0 4

Drain-blocking

52

8.1 Meta-analysis

The general picture across the literature review is that the soil respiration would decrease, with

primary productivity and methane fluxes increasing. Evidence is more equivocal regarding DOC but

the majority suggest an increase in concentration upon drain-blocking, but a decrease in flux. There

is no field data on POC, dissolved CO2 or total carbon budgets. Rowson et al. (submitted) have

proposed total C budgets of two drained peat catchments and found values between 34 and 95

tonnes C/km2/yr, but provide no pre-blocking data. The meta-analysis suggests there is a 55%

probability of carbon budget improvement but only a 34% chance of greenhouse gas improvement.

8.2 Modelling

Given the values for a drained site then modelling would predict that drain-blocking decreases the

carbon budget by -4.8 tonnes C/km2/yr. When grazing is present the effect of drain-blocking is -10.1

tonnes C/km2/yr, when it its not present the effect is 0.6 tonnes C/km2/yr, i.e. when there is no

grazing drain-blocking could slightly improve carbon budgets. When burning is present then the

effect of drain blocking is -15.3 tonnes C/km2/yr while when it is not present the effect of drain-

blocking is 5.8 tonnes C/km2/yr, i.e. drainage may slightly increase C budget. In terms of the

equivalent greenhouse gas budget drain-blocking would be expected to increase the budget due to

the increases in methane emissions, in this case an increase in emissions of 19 tonnes CO2

equivalent/km2/yr. A recent study by Worrall et al. (submitted) has suggested that in terms of

reducing greenhouse gas emissions drain-blocking was only successful 20% of the time.


No complete budgets are available that compare before and after intervention.

Degrees of drainage are not considered here

Modelling does not consider transitionary sinks, i.e. the infilling of the drain itself.


In terms of ancillary effects it is expected that drainage would lower water tables, but effects upon

runoff have been reviewed by Holden et al. (2004). Increases in runoff would be expected to

enhance POC and DOC losses. The blocking of drains will restore the ecosystem and prevent

dissection and gully development.

8.5 Costs

The Peat Compendium suggests that gully-blocking with plastic piling at 15 m spacing would cost

£2500 /km of gully, it would be considered that grip-blocking should be a similar cost.

Drain-blocking

53

8.6 References:



Berglund, O, Berglund, K and Persson, L (2007) Effect of drainage depth on the emission of CO2 from

cultivated organic soils, 133-138 in: Okruszko, T (Ed) Wetlands: Proceedings of the International

Conference W3M wetlands: Modelling, Monitoring, Management, Wierzba, Poland 22-25

September 2005: Routledge

Best, E.P.H and Jacobs, F.H.H (1997) The influence of raised water table levels on carbon dioxide and

methane productionin ditch-disected peat grasslands in the Netherlands, Ecological Engineering 8,

129-144

Bridgham SC., Richardson CJ., Maltby E., et al., (1991). Cellulose decay in natural and disturbed

peatlands in North Carolina. Journal of Environmental Quality 20, 695-701.

Bubier JL., Costello A., Moore TR., et al. (1993). Microtopography and methane flux in boreal

peatlands, Northern Ontario, Canada. Canadian Journal of Botany 71, 1056-1063.

Chojinicki, B.H, Augustin, J and Olejnik, J (2007) Impact of reflooding on greenhouse gas exchange of

degraded fen peatlands, in: Robroek, B, Schaepman-Strub, G, Limpens, J, Berendse, F and Breeuwer,

A (Eds) (2007) Proceedings of the First International Symposium on Carbon in peatlands, 15-18th

April 2007, Wageningen, The Netherlands, 141pp, Wageningen University, Wageningen, NL.

Conlin, M, Turetsky, M, Harden, J and McGuire, D (2007) Soil climate controls on C cycling in an

Alaskan fen: responses to water table mediated by vegetation, in: Robroek, B, Schaepman-Strub, G,

Limpens, J, Berendse, F and Breeuwer, A (Eds) (2007) Proceedings of the First International

Symposium on Carbon in peatlands, 15-18th April 2007, Wageningen, The Netherlands, 141pp,

Wageningen University, Wageningen, NL.

Christensen TR., and Cox P. (1995) Response of methane emission from Arctic tundra to climatic

change – results from a model simulation. . Tellus Series B – 47, 301-309.



Diamond, J and Middleton, J (2007) The effect of moisture on the decomposition processes in a

peat-extracted bog in Southern Ontario, Canada, in: Robroek, B, Schaepman-Strub, G, Limpens, J,

Berendse, F and Breeuwer, A (Eds) (2007) Proceedings of the First International Symposium on

Carbon in peatlands, 15-18th April 2007, Wageningen, The Netherlands, 141pp, Wageningen

University, Wageningen, NL.

Gibson, H.S., Worrall, F., Burt, T.P., and J.K. Adamson. DOC budgets of drained peat catchments.

Hydrol Process.. (submitted).



Drain-blocking

54




Holden, J (2005) Peatland hydrology and carbon release: why small scale process matters,

Philosophical Transactions of the Royal Society A, 2891-2913

Jones, J.B. Jr and Mulholland, P.J (1998) Carbon Dioxide Variation in a Hardwood Forest Stream: An

Integrative Measure of Whole Catchment Soil Respiration, Ecosystems 1: 193-196

Komulainen, VM; Tuittila, ES; Vasander, H, et al. (1999) Restoration of drained peatlands in southern

Finland: initial effects on vegetation change and CO2 balance. Journal of Applied Ecology 36, 634-

648.

Lafleur, PM; Moore, TR; Roulet, NT, et al. (2005) Ecosystem respiration in a cool temperate bog

depends on peat temperature but not water table. Ecosystems 8, 619-629.

Lloyd, C.R (2006) Annual carbon balance of a managed wetland meadow in the Somerset Levels, UK,

Agricultural and Forest Meteorology 138:1-4, 168-179






Moore, P.D (2002) The future if cool temperate bogs, Environmental Conservation 29:1, 3-20

Nieveen, JP; Campbell, DI; Schipper, LA, et al. (2005) Carbon exchange of grazed pasture on a

drained peat soil. Global Change Biology 11, 607-618.



Parmentier, F.J.W, Van der Molen, M.K, de Jeu, R.A.M, Hendricks, D.M.D and Dolman, A.J (2008) CO2

fluxes and evaporation on a peatland in the Netherlands appear not affected by water table

fluctuations, Agricultural and forest meterology (2008), doi:10.1016/j.agrformet.2008.11.007

Petrone, R.M., Waddington, J.M., Price, J.S., 2001. Ecosystem scale evapotranspiration and net CO2

exchange from a restored peatland. Hydrol. Proc. 15, 2839-2845.

Rowson, J.G., Gibson, H.S., Worrall, F., Ostle, N., Burt, T.P. and J.K.Adamson. The complete carbon

budget of a drained peat catchment. JGR-Biogeosciences (submitted).

Salantaus, T (2007) Peatland restoration-induced changes in the DOC of recipient waters, in :

Robroek, B, Schaepman-Strub, G, Limpens, J, Berendse, F and Breeuwer, A (Eds) (2007) Proceedings

of the First International Symposium on Carbon in peatlands, 15-18th April 2007, Wageningen, The

Netherlands, 141pp, Wageningen University, Wageningen, NL.

Drain-blocking

55

Tuittila, ES; Komulainen, VM; Vasander, H, et al. (2000) Methane dynamics of a restored cut-away

peatland. Global Change Biology 6, 569-581.

Updegraff, K; Bridgham, SD; Pastor, J, et al. (2001) Response of CO2 and CH4 emissions from

peatlands to warming and water table manipulation. Ecological Application 11, 311-326.

Van den Bos, R (2003) Restoration of former wetlands in the Netherlands; effect on the balance

between CO2 and CH4 source, Netherlands journal of Geosciences 82(4), 325-332

Vasander, H, Tuittila, E.S, Lode, E, Lundin, L, Ilomets, M, Sallantaus, T, Heikkila, R, Pitkanen, M.L and

Laine, J (2003) Status and restoration of peatlands in northern Europe, Wetlands Ecology and

Management 11: 51-63

Veenedndaal, E, Hendricks, D, Kroon, P, Schrier,A, Van Huissteden, K, Hensen, A, Duiyzer, J, Leffelaar,

P, Berendse, F and Dolman, H (2007) Carbon balance Greenhouse gas fluxes in intensive and

extensive managed grasslands on peat, in: Robroek, B, Schaepman-Strub, G,

Worrall , Gibson, F.H and Burt, T.P, (2007b) Modelling the impact of drainage and drain-blocking on

dissolved organic carbon release from peatlands, Journal of Hydrology 338, 15– 27

Worrall, F, Armstrong A, Holden, J (2007) Short-term impact of peat drain-blocking on water colour,

dissolved organic carbon concentration, and water table depth, Journal of Hydrology 337: 315-325

Worrall, F, Reed, M, Warburton, J and Burt, T (2003) Carbon budget for a British upland peat

catchment, The Science of the Total Environment 312(1-3), 133-146

Worrall, F., Evans, M.G., Bonn, A., Reed, M., Chapman, D., and J. Holden. Can carbon offsetting pay

for ecological restoration in uplands? J. Appl. Ecology (submitted).

Grazing removal

56

9. Grazing removal


CO2

Primary

productivity


CO2

Net ecosystem

exchange

Total C budget

Ward et al

(2007)

Worrall et al.

(2007)

Garnett et al.

(2000)

Charman and

Smith (1992)

Anderson and

Radford (1994)

Meyles et al

(2006)

Orr et al (2008)

Grazing removal

57

Mackay and

Tallis (1995)

Dawson et al

(2002)

Nieveen et al

(2005)

Kauppi and

Tomppo (1993)

No. of samples 1 4 1 2 5 1 1

No. with

improvement 1 2 1 1 5 1 0

Grazing removal

58

9.1 Meta-analysis

With the removal of grazing it would be expected that vegetation would recover and that the depth

to the water table would increase. Given these it is perhaps surprising that the only evidence is that

soil respiration will decrease upon removal of grazing. But then recovery in vegetation and rise in

water tables has the expected affect upon primary productivity, methane and POC, i.e. primary

productivity increases, methane fluxes increases and POC fluxes decrease. Where competing results

have been observed for primary productivity it was due to a change in species composition. The

meta-analysis suggests that there is a 65% chance of grazing removal giving a carbon budget benefit

and a 78% chance of greenhouse gas benefit. The values here are for the vegetation and soil and not

related to the livestock itself.

9.2 Modelling

The presence of grazing decreases the carbon budget by -3.6 tonnes C/km2/yr. When there is

drainage present the effect of drainage increases to 8.9 tonnes C/km2/yr while when there is no

drainage present the effect of grazing is only 1.1 tonnes C/km2/yr. When there is burning present the

effect of grazing is 1.1 tonnes C/km2/yr but when burning is not present then the effect of grazing is

6.1 tonnes C/km2/yr. With respect to greenhouse gases it would be expected that grazing removal

would decrease emissions.


No complete budgets are available.

It has been assumed that grazing is by sheep.

It is not known whether long term and uncontrolled vegetation recovery would be good for peat soils as this may mean succession to shrubs and small trees.

The greenhouse gas emissions of the livestock is not included.


Grazing has a clear benefit of agricultural production, or for recreational hunting if deer are also

considered. Therefore, the removal of grazing involves the loss of production. The removal of grazing

with its consequences for vegetation recovery could mean habitat recovery.

9.5 Costs

The cost of of grazing removal is unknown.

9.6 References:

Grazing removal

59

Anderson, P and Radford, E (1994) Changes in vegetation following reduction in grazing pressure on

the National Trust’s Kinder Estate, Peak District, Derbyshire, England, Biological Conservation 69, 55-

63

Charman, D.J and Smith, R. S (1992) Forestry and blanket mires of Kielder forest, Northern England:

Long term effects of vegetation, in: Bragg, O.M, Hulme, P.D, Ingram, H.A.P and Robertson, R.A (eds)

Peatland Ecosystems and Man: An Impact Assessment, Department of Biological Sciences, University

of Dundee, UK, 226-230



Garnett, M.H., Ineson, P. and Stevenson, A.C., 2000. Effects of burning and grazing on carbon

sequestration in a Pennine blanket bog, UK. Holocene, 10(6): 729-736.

Kauppi, P.E and Tomppo, E (1993) Impact of forests on net national emissions of Carbon Dioxide in

West Europe, Water, Air and Soil Pollution 70: 187-196

Mackay, A.W and Tallis, J.H (1995) Summit-type blanket mire erosion in the forest of Bowland,

Lancashire, UK: Predisposing factors and implications for conservation, Biological Conservation 76:

31-44

Meyles, E.W, Williams, A.G, Ternan, J.L, Anderson, J.M and Dowd, J.F (2006) The influence of grazing

on vegetation, soil properties and stream discharge in a small Dartmoor catchment, Southwest

England, UK, Earth Surface Processes and Landforms 31, 622-631

Nieveen, J.P, Campbell, D.I, Schipper, L.A and Blair, I.J (2005) Carbon exchange of grazed pasture on

a drained peat soil, Global Change Biology 11, 607-618



Ward, S.E, Bardgett, R.D, McNamara, N.P, Adamson, J.K and Ostle, N.J (2007) Long-term

Consequences of Grazing and Burning on Northern Peatland Carbon Dynamics, Ecosystems 10: 1069-

1083

Worrall, F, Armstrong, A and Adamson, J.K (2007) The effects of burning and sheep-grazing on water

table depth and soil water quality in a upland peat, Journal of Hydrology 339: 1-14

Revegetation

60

10. Revegetation


CO2

Primary

productivity


CO2

Net ecosystem

exchange

Total C budget

Trinder et al.

(2008)

Evans et al.

(2006)

Orr et al

(2008)

Macdonald et

al (1998)

Mackay and

Tallis (1995)

Anderson

(2002)

Bortoluzzi et

al (2006)

Revegetation

61

Biasi et al

(2008)

Limpens et al

(2008)

Petrone et al.

(2001)

Marinier et al.

(2004)

Kivimaki et al.

(2008)

Keller et al

(2005)

No. of

samples 7 6 7 5 3 0 4 5

No. with

improvement 1 6 0 2 3 0 2 4

Revegetation

62

10.1 Meta-analysis

In some cases use of lime in order to aid establishment of vegetation is causing the unexpected

results, for example decreasing soil respiration reported by Keller et al. (2005). In other cases we see

rise in both soil respiration and primary productivity, the rise in soil respiration is due to a rise in root

respiration with the return of vegetation, the presence of vegetation seems also to increase

methane fluxes which maybe as a result of increased root exudates upon the return of vegetation.

The recovery of vegetation limits soil erosion and so POC fluxes decline, but the evidence for a

change in DOC is equivocal. The meta-analysis suggests that there is 70% chance of carbon budget

improvement but only 45% chance of greenhouse gas improvement.

10.2 Modelling

For pristine soils, the modelling suggests:

(i) r2 = 96%, n = 474

Equation (i) can be used to assess the impact of revegetation, given that equation a 1% decrease in

bare soil leads to 2.1 tonnes C/km2/yr improvement in the C budget. However, equation (i) considers

only the pristine subset within the dataset, when considering all data the equation becomes:

(iii) r2 = 44%, n= 4171

In this case the carbon budget lapse rate is 4.3 tonnes C/km2/yr/100m, and the bare soil rate has

increased to 3.7 ± 0.1 tonnes C/km2/yr/% bare soil. However, is there an interaction effect in which

revegetation is more or less effective at greater altitude? Therefore, equation (iii) is recalculated

with an interaction term A*fbaresoil and the equation becomes:

(iv) r2=44%,

n = 4170

This would imply that the interaction although significant is slight ie. the bare soil rate is 4.9 ± 0.4

tonnes C/km2/yr decreases by 0.27 tonnes C/km2/yr for every 100m decrease in altitude and so

revegetation has a bigger effect at greater altitude.

Revegetation

63


No complete budgets are available for any revegetated sites

We cannot at this stage differentiate between revegetation strategies or even the behaviour of the species.


The revegetation of bare soil has multiple benefits. Firstly, habitat restoration with its recovery of

biodiversity. Loss of POC can be dramatic for bare peat and so revegetation causes a decline in

suspended sediment with concomitant benefits for stream ecology and reservoir function.

10.5 Costs

The cost of revegetation as reported from the Peat Compendium suggests that stabilisation as a

component of revegetation cost between £8800 and £170000 /km2: the higher values were reported

for Bleaklow where helicopters had to be used. For reseeding, costs range from £9500 to £90000

/km2, or if planting was used instead of re-seeding then costs are considerably higher at £270000

/km2.

10.6 References:



Biasi, C, Lind, S.E, Pekkarinen, N.M, Huttunen, J.T and Shurpali, N.J (2008) Direct experimental

evidence for the contribution of lime to CO2 release from managed peat soil, Soil Biology &

Biochemistry 40, 2660–2669

Bortoluzzi, E, Epron, D, Siegenthaler, A, Gilbert, D and Buttler, A (2006) Carbon balance of a

European mountain bog at contrasting stages of regeneration New Phytologist, 172: 708–718

Evans, M, Warburton, J and Yang, J (2006) Eroding blanket peat catchments: Global and local

implications of upland organic sediment budgets, Geomorphology 79, 45-57

Keller, J.K and Bridgham, S.D, Chapin, C.T and Iversena, C.M (2005) Limited effects of six years of

fertilization on carbon mineralization dynamics in a Minnesota fen, Soil Biology & Biochemistry 37

(2005) 1197–1204

Kivimaki, S.K, Yli-petays, M and Tuittila, E.S (2008) Carbon sink function of sedge and sphagnum

patches in a restored cut-away peatland: increased functional diversity leads to higher production,

Journal of Applied Ecology 45: 921-929

Revegetation

64







Mackay, A.W and Tallis, J.H (1995) Summit-type blanket mire erosion in the forest of Bowland,

Lancashire, UK: Predisposing factors and implications for conservation, Biological Conservation 76:

31-44

Mackenzie, S (1992) The impact of catchment liming on blanket bogs, in: Bragg, O.M, Hulme, P.D,

Ingram, H.A.P and Robertson, R.A (eds) Peatland Ecosystems and Man: An Impact Assessment,

Department of Biological Sciences, University of Dundee, UK, 31-37

Marinier, M, Glatzel, S and Moore, T.R (2004) The role of cotton-grass (Eriophorum vaginatum) in

the exchange of CO2 and CH4 at two restored peatlands, eastern Canada, Ecoscience 11: 2, 141-149



Petrone, R.M, Waddington, J.M and Price, J.S (2001) Ecosystem scale evapotranspiration and net

CO2 exchange from a restored peatland, Hydrological processes 15: 2839- 2845

Trinder, C.J, Artz, R.E and Johnson, D (2008) Contribution of plant photosynthate to soil respiration

and dissolved organic carbon in a naturally recolonising cutover peatland Soil Biology & Biochemistry

40 (2008) 1622–1628.

Vegetation cutting

65

11. Vegetation cutting

11.1 Meta-analysis & Modelling

We found no studies covering the effects of vegetation cutting on carbon budgets. As an

approximation we could assume that it was similar to that of burning, i.e. vegetation removal would

cause loss of biomass and cause rises in the water table. Cutting is less like grazing as grazing is a

slow attrition of the vegetation with vegetation still largely present whereas cutting would normal

mow or flail to near the ground surface just as in a “cool” nurn. It is possible therefore, we could

assume that cessation of cutting would be a carbon benefit.


No complete or even partial studies were available to review.

Present carbon models would have to assume that vegetation cutting was equivalent to managed burning.

Information on carbon flux pathways for areas where there has been vegetation cutting is presently being collected as part of a trial in the Goyt Valley sponsored by Natural England and United Utilities due to finish this May.


Cutting and mowing are commonly used as an alternative to burning and compared to burning

cutting has the advantage of no risk of runaway wildfires or of hot burns destroying litter or soil

reserves of carbon. The cutting or mowing of vegetation is distinct in that in order to save cost it is

mostly performed so that the cut biomass is left on the site in which case we could imagine increases

in respiration but the biomass left behind is a carbon input and will add to the litter layer.

Furthermore, the presence of cut vegetation may act as mulch and keep underlying peat soils wet

and help prevent surface erosion.

11.4 Costs

The Peat Compendium suggests cost of between £12800 and £20000 /km2 for mowing where in

house staff are available.

Vegetation change

66

12. Vegetation change

12.1 Meta-analysis & Modelling We found no studies covering the effects of vegetation change other than those that could be

considered in other categories, e.g. afforestation. It is difficult to assume that changes in vegetation

is similar to other management techniques, e.g. conversion of Calluna-dominated to Molinia-

dominated peat soils, is not the same as re-vegetation. However, we might consider that the change

to a peat soil dominated by peat-forming vegetation types would provide a carbon benefit over

other vegetation types, for example, Calluna-dominated changed to Sphagnum-dominated .

However, in the case of a transition to Sphagnum-dominated there will be rises in water table that

could mean an increase in methane flux.


No complete or even partial studies were available to review

Present carbon models cannot discriminate between vegetation types.


It is unclear what benefits or disbenefits might occur with a change between vegetation types, for

example a transition from Molinia-dominated to Calluna-dominated.

12.4 Costs

The nearest equivalent cost for vegetation change is for revegetation and or mowing. For reseeding,

costs range from £9500 to £90000 /km2, or if planting was used instead of re-seeding then costs are

considerably higher at £270000 /km2. For mowing there is a cost of between £12800 and £20000

/km2.

Wildfire suppression

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13. Wildfire suppression

13.1 Meta-analysis & Modelling

We found no studies covering the effects of vegetation cutting on carbon budgets. As an

approximation we could assume that it was similar to that of burning though anecdotal evidence

suggests that wildfires tend to burn “hot” while managed burns tend to burn “cool”.


No complete or even partial studies were available to review


Wildfire suppression would have the same benefits and disbenefits as the cessation of managed

burning.

13.4 Costs

The Peat Compendium can give no costs of wildfire suppression and unlike the cessation of managed

burning, wildfire suppression would involve an ongoing management cost.

best practices for managing soil organic matter in agriculture

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