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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.
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.
4.3 Gaps, assumptions and limitations
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.
4.4 Associated benefits or disbenefits
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
Anderson, D.E (2002) Carbon accumulation and C/N ratios of peat bogs in North-West Scotland,
Scottish Geographical Journal 118:4, 323-341
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
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
Author: Soil Respiration of
CO2
Primary
productivity
Methane DOC POC Dissolved
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.
5.3 Gaps, assumptions and limitations
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
5.4 Associated benefits or disbenefits
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
Methane DOC POC Dissolved
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
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.
6.3 Gaps, assumptions and limitations
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.
6.4 Associated benefits or disbenefits
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
Author: Soil Respiration of CO2 Primary
productivity
Methane DOC POC Dissolved
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.
7.3 Gaps, assumptions and limitations
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.
7.4 Associated benefits or disbenefits
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
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
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
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
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, 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
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.
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
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
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
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.
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
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
Author: Soil Respiration of CO2 Primary
productivity
Methane DOC POC Dissolved
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.
8.3 Gaps, assumptions and limitations
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.
8.4 Associated benefits or disbenefits
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:
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
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.
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
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).
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
Drain-blocking
54
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
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
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
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
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.
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
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
Author: Soil Respiration of
CO2
Primary
productivity
Methane DOC POC Dissolved
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.
9.3 Gaps, assumptions and limitations
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.
9.4 Associated benefits or disbenefits
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
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
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
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
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
Author: Soil Respiration of
CO2
Primary
productivity
Methane DOC POC Dissolved
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
10.3 Gaps, assumptions and limitations
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.
10.4 Associated benefits or disbenefits
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:
Anderson, D.E (2002) Carbon accumulation and C/N ratios of peat bogs in North-West Scotland,
Scottish Geographical Journal 118:4, 323-341
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Revegetation
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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.
11.2 Gaps, assumptions and limitations
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.
11.3 Associated benefits or disbenefits
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.
12.2 Gaps, assumptions and limitations
No complete or even partial studies were available to review
Present carbon models cannot discriminate between vegetation types.
12.3 Associated benefits or disbenefits
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
67
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”.
13.2 Gaps, assumptions and limitations
No complete or even partial studies were available to review
13.3 Associated benefits or disbenefits
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.