Wetlands

3.5

WETLANDS

Wetlands include land that is covered or saturated by water for all or part of the year (e.g. peatland) and that does
not fall into the forest land, cropland, grassland or settlements categories defined in Chapter 2 of this report(Section 2.2, Land Categories)1. This category can be subdivided into managed and unmanaged according tonational definitions. It includes reservoirs as a managed subdivision and natural rivers and lakes as unmanaged
subdivisions. Forest land, cropland, and grassland that are established on peaty or wet soils are addressed in
Sections 3.2, 3.3, and 3.4, respectively, of this chapter. Rice paddies are addressed in the Agriculture chapter of
the IPCC Guidelines and GPG2000. Flooding and wetland drainage are included in the IPCC Guidelines in
Section 5.4.3 Other Possible Categories of Activity.
For purposes of estimating greenhouse gas emissions, it is necessary to distinguish between managed andunmanaged wetlands. In this report, managed wetlands are those in which the water table is artificially changed(e.g. drained peatlands) or those that are created through human activity (e.g., damming a river). Major
greenhouse gas emissions from managed wetlands, and the sections of this report in which they are estimated,
are summarised in Table 3.5.1.
TABLE 3.5.1
SECTIONS AND APPENDICESADDRESSING MAJOR GREENHOUSE GAS EMISSIONS FROM MANAGED WETLANDS IN THIS REPORT

PeatlandFlooded Land2

CO2

Appendix 3a.3

Appendix 3a.3

CH4

Not addressed

Appendix 3a.3

N2O

Appendix 3a.3

Appendix 3a.3

Section 3.5

Section 3.5

Not addressed(drainage and rewetting of forest soils
is discussed in Appendix 3a.2)
Appendix 3a.3
(drainage and rewetting of forest soils
is discussed in Appendix 3a.2)

Covered in Appendix 3a.3
(no distinction is made based on theage of the reservoir)
Covered in Appendix 3a.3
(no distinction is made based on theage of the reservoir)

Wetlands Remaining Wetlands

Land Converted to Wetlands
CO2
CH4

N2O

3.5.1

Wetlands Remaining Wetlands

This category is addressed in Appendix 3a.3 Wetlands Remaining Wetlands: Basis for future methodologicaldevelopment.

3.5.2

Land Converted to Wetlands

In this section, CO2 emissions associated with either peat extraction or flooding are addressed. The conversion oflands to wetlands may be an important component of national estimates of deforestation (or other nationally
important land use conversions). For conversions related to peat extraction, carbon stock changes associated withliving biomass and soil are addressed below. For conversions related to flooding, only the carbon stock change
associated with the loss of living biomass is addressed.
Lands converted to wetlands include conversions from forest land, cropland, grassland and settlements to thiscategory. The most likely conversions are conversions from forest land to wetlands (e.g. rewetting of peatlands
1

The definition used in this report agrees with common definitions used in the Ramsar Convention on Wetlands and theConvention on Biological Diversity (CBD).

2

Flooded lands are defined as water bodies regulated by human activities for energy production, irrigation, navigation,
recreation, etc. and where substantial changes in water area due to water regulation occur. Regulated lakes and rivers,
where the main pre-flooded ecosystem was a natural lake or river, are not considered as flooded lands. Rice paddies are
addressed in the Agriculture Chapter of the IPCC Guidelines and GPG2000.

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Chapter 3: LUCF Sector Good Practice Guidancedrained for forestry purposes), conversions related to peat extraction (conversion of natural peatlands to managed
lands), or conversions to flooded land (for hydroelectric or other purposes). Methodologies for rewetting are notincluded due to the scarcity of available data (Appendix 3a.2 addresses emissions of non-CO2 greenhouse gases
from drainage and rewetting, with emphasis on drainage). As shown in Equation 3.5.1, guidance on estimating
carbon stock change in land converted to wetlands covers conversion to two possible land uses: peat extraction
and flooding.
EQUATION 3.5.1
CHANGE IN CARBON STOCKS IN LAND CONVERTED TO WETLANDS∆CLW = ∆CLW peat + ∆CLW flood
Where:∆CLW = change in carbon stocks in land converted to wetlands, tonnes C yr-1
∆CLW peat = change in carbon stocks in land converted to peat extraction (Section 3.5.1), tonnes C yr-1
∆CLW flood = change in carbon stocks in land converted to flooded land (Section 3.5.2), tonnes C yr-1
The carbon stock change in tonnes C is converted to Gg CO2 emissions by multiplying the value with 44/12 and10-3 to correspond to the reporting requirements. Emissions are reported as positive values and removals as
negative values (Equation 3.5.1 is expected to result in a loss of carbon). For more details on reporting and therule on the signs, see Section 3.1.7 and Annex 3A.2 (Reporting Tables and Worksheets).
Figure 3.1.2 provides a general decision tree to select the appropriate tier for land conversion and is applicable forland converted to wetlands. If data are available, the choice of tier should be performed separately for each land
conversion type (forest land to wetlands, grassland to wetlands, cropland to wetlands, other land to wetlands).

3.5.2.1

C HANGE IN CARBON STOCKS IN LAND CONVERTED TO
PEAT EXTRACTION

3.5.2.1.1 METHODOLOGICAL ISSUES
A method to estimate emissions from land converted to peat extraction is given below. Neither emissions fromorganic soils managed for peat extraction nor land-use changes associated with organic soils managed for peat
extraction are dealt with explicitly in the IPCC Guidelines. Emissions from peat combustion are dealt with in the
Energy section of the IPCC Guidelines. Therefore, the method below addresses only emissions from removal ofvegetation from land prepared for peat extraction and changes in soil organic matter due to oxidation of peat in
the aerobic layer on the land during the extraction. The removal of peat is covered by the estimates from peat
combustion in the energy section and is not considered in this section. This method, and the associated default
values used for Tier 1 estimates, can be applied for both lands with ongoing peat extraction (to be reported under
Wetlands remaining wetlands subcategory) and land converted to peat extraction.

3.5.2.1.1.1

Choice of Method

The estimate of carbon stock changes from land converted to peat extraction has two basic elements, as shown inEquation 3.5.2. Equation 3.5.2 calculates a loss of carbon.
EQUATION 3.5.2
ANNUAL CHANGE IN CARBON STOCKS IN LAND CONVERTED TO PEAT EXTRACTION∆CLW peat = ∆CLW peatLB + ∆CLW peatSoils
Where:∆CLW peat = annual change in carbon stocks in land converted to peat extraction, tonnes C yr-1
∆CLW peatLB = annual change in carbon stocks in living biomass, tonnes C yr-1
∆CLW peatSoils = annual change in carbon stocks in soils, tonnes C yr-1
It is assumed that the dead organic matter pool is not significant. If a country has data on dead organic matter, it
can be included in the estimate under Tier 2 or 3 methods.
Carbon stock changes in living biomass associated with the conversion of land to peat extraction are estimatedby Equation 3.5.3.

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EQUATION 3.5.3
ANNUAL CHANGE IN CARBON STOCKS IN LIVING BIOMASSIN LAND CONVERTED TO PEAT EXTRACTION∆CLW peatLB = Σ Ai ● (BAfter – BBefore) i ● CF
Where:∆CLW peatLB = annual change in carbon stocks in living biomass in land converted to peat extraction,
tonnes C yr-1
Ai = area of land converted annually to peat extraction from original land use i, ha yr-1
BBefore = aboveground biomass immediately before conversion to peat extraction, tonnes d.m. ha-1
BAfter = aboveground biomass immediately following conversion to peat extraction, tonnes d.m. ha-1
(default = 0)
CF = carbon fraction of dry matter (default = 0.5), tonnes C (tonnes d.m.)-1
The method follows the approach in IPCC Guidelines Section 5.2.3 (Forest and Grassland Conversion) and isconsistent with the tiered approaches for estimating carbon stock changes in living biomass outlined in Sections
3.2.2, 3.3.2, and 3.4.2. As the equation shows, the amount of living aboveground biomass that is cleared for peat
extraction is estimated by multiplying the land area converted annually to peat extraction by the difference incarbon stocks between biomass in the original land use prior to conversion and in the peatland after conversion.
Where forests are converted to peatlands and the timber cleared is reflected in harvesting statistics, the lattershould be adjusted by the amount of timber harvested from BBefore to avoid double-counting.
The default assumption for a Tier 1 estimate of carbon stock changes in living biomass on land converted to peat
extraction are that all aboveground biomass present before conversion to peat extraction will be lost in the same
year as the conversion takes place and that carbon stocks in living biomass following conversion (BAfter) areequal to zero. It is good practice for countries to estimate the area of land converted to peat extraction fromforest, by major forest categories and to use default carbon stock values from Annex 3A.1, Tables of default
values for Section 3.2 (Forest land), to develop estimates of BBefore for each initial forest category, and each
initial other land-use category including unmanaged peatland. Where grassland is the previous land use, default
values for aboveground biomass should be taken from Table 3.4.2.
In cases where fires are used to clear vegetation, emissions of non-CO2 gases, i.e., CH4 and N2O will also occur.
These emissions can be estimated under Tiers 2 and 3 following guidance provided in Section 3.2.1.4. Drainageof peatland also increases N2O emissions. These emissions can be estimated following guidance provided inAppendix 3a.3, N2O emissions from organic soils managed for peat extraction.
CO2 emissions from soils occur at several stages in the peat process, as shown in Equation 3.5.4.
EQUATION 3.5.4
ANNUAL CHANGE IN CARBON STOCKS IN SOILS IN LAND CONVERTED TO PEAT EXTRACTION∆CLW peatSoils = ∆C drainage + ∆C extraction + ∆C stockpiling + ∆C restoration
Where:∆CLW peatSoils = annual change in carbon stocks in soils in land converted to peat extraction, tonnes C yr-1
∆C drainage = annual change in carbon stocks in soils during drainage, tonnes C yr-1
∆C extraction = annual change in carbon stocks in soils during peat extraction (excluding the amount ofcarbon in the extracted peat), tonnes C yr-1
∆C stockpiling = annual change in carbon stocks in soils during stockpiling of peat prior to removal for
combustion, tonnes C yr-1
∆C restoration = annual change in carbon stocks in soils due to practices undertaken to restore previously
cultivated lands, tonnes C yr-1
Tier 1: In the case of land converted to peat extraction, only the effect of peat drainage (∆C drainage) is considered
under Tier 1. The Tier 1 method relies on basic area identification and default emission factors and the basic
method for estimating carbon emissions from organic soils converted to peat extraction is shown in Equation
3.5.5. This equation is applied at an aggregate level to a country’s entire area of organic soils converted to peat

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extraction, divided into nutrient-rich and nutrient-poor, using default emission factors. At this time, it is only
possible to provide a method and data for estimating the average changes in carbon stocks associated with peatdrainage over longer periods, although the emissions will be higher in the first year of drainage than in later
years.
EQUATION 3.5.5
ANNUAL CHANGE IN CARBON STOCKS IN SOILSDUE TO DRAINAGE OF ORGANIC SOILS CONVERTED TO PEAT EXTRACTION∆C drainage = ANrich ● EFNrich + ANpoor ● EFNpoor
Where:∆C drainage = annual change in carbon stocks in soils due to drainage of organic soils converted to peat
extraction, tonnes C yr-1
ANrich = area of nutrient rich organic soils converted to peat extraction, ha
ANpoor = area of nutrient poor organic soils converted to peat extraction, ha
EFNrich = emission factor for changes in carbon stocks in nutrient rich organic soils converted to peat
extraction, tonnes C ha-1 yr-1
EFNpoor = emission factor for changes in carbon stocks in nutrient poor organic soils converted to peat
extraction, tonnes C ha-1 yr-1
Tier 2: The Tier 2 method can extend the Tier 1 method, if area data and country-specific emission factors areavailable. In this case, countries may be able to subdivide activity data and emission factors according to peat
fertility, peat type and drainage intensity, and/or previous land use or land cover.
Tier 3: Tier 3 methods require statistics on the area of organic soils managed for peat extraction according tosite type, fertility, time since drainage, and/or time since restoration, which could be combined with appropriate
emission factors, and/or process-based models. Studies utilising information on changes in soil bulk density,
carbon content and peat depth could also be used to detect changes in soil C stocks provided the sampling
intensity was sufficient and covered the entire peat layer. Such data should be corrected for carbon losses due todissolved organic carbon leaching, losses of dead organic matter through runoff, or as CH4 emissions.

3.5.2.1.1.2

Choice of Emission/Removal Factors

Tier 1: When estimating the carbon stock change for organic soils converted to peat extraction under Tier 1, it
is good practice to use the default emission factors presented in Table 3.5.2.
TABLE 3.5.2
EMISSION FACTORS AND ASSOCIATED UNCERTAINTY FOR ORGANIC SOILS AFTER DRAINAGE
Emission Factor
tonne C ha yr-1

Uncertainty atonne C ha yr-1

Boreal and Temperate
Nutrient Poor (EFNpoor )0.2

0 to 0.63

Laine and Minkkinen, 1996; Alm et al., 1999;
Laine et al., 1996; Minkkinen et al., 2002

Nutrient Rich (EFNrich )1.1

0.03 to 2.9

Laine et al., 1996; LUSTRA, 2002;
Minkkinen et al., 2002; Sundh et al., 2000

2.0

0.06 to 6.0

Calculated from the relative difference
between temperate (nutrient poor) andtropical in Table 3.3.5.

Region/Peat Type

Tropical

Reference/Comment baRange of underlying datab

The boreal and temperate values have been developed as the log-normal mean from a review of paired plot measurements, assumingthat conditions on organic soils converted to peat extraction are lightly drained only. Most of the data are from Europe.

Boreal countries that do not have information on areas of nutrient-rich and nutrient-poor peatland areas should
use the emission factor for nutrient-poor peatlands. Temperate countries that do not have such data should use
the emission factor for nutrient-rich peatland. For tropical countries, only a single default can be provided at thistime.
Tier 2: Tier 2 requires country-specific data that takes into account management practices such as drainage ofdifferent peat types, and drainage intensity.

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Tier 3: Under Tier 3, all parameters should be country-defined using more accurate values rather than thedefaults. The literature is sparse and results are sometimes contradictory, so it is good practice to derive countryspecific emission factors by measurements against appropriate reference virgin sites. Data should be shared
between countries with similar environmental conditions.

3.5.2.1.1.3

Choice of Activity Data

Tier 1: The activity data required for all tiers is the area of organic soil converted to peat extraction. For theestimation of carbon stock change from living biomass, this overall area value is used, while for the estimate ofcarbon stock change from organic soil, a distinction between nutrient-rich and nutrient poor organic soils isneeded. Ideally, under Tier 1, countries will obtain national data on the areas converted to peat extraction andtheir original land uses. Possible sources of such data are national statistics, peat mining companies andgovernment ministries responsible for land use. It can be assumed that the proportion of nutrient-rich versus
nutrient-poor soils is similar to the relative importance of these peatland types at national level.
Tier 2: Under Tier 2, countries can incorporate information based on the original land use, peat type andfertility, and intensity of peat disturbance and drainage of the areas of organic soils converted to peat extraction.
This information could be gathered from regular updates of the national peatland inventory.
Tier 3: Under Tier 3, detailed information on the original land use, peat type and fertility, and intensity of peat
disturbance and drainage of the areas of organic soils converted to peat extraction may be needed. The modelingapproach used will determine specific data needs and level of disaggregation.

3.5.2.1.1.4

Uncertainty Assessm ent

For the estimation of emissions from land conversions to peat, the principal uncertainties are related to area
estimates and emission factors.
Tier 1: The sources of uncertainty in the Tier 1 method are from the use of global or national averages forcarbon stocks in forests before conversion and coarse estimates of land areas and their original use converted topeat extraction, although most of the converted area is likely to be more or less densely treed peatland. Most
default values in this method do not have corresponding error ranges associated with them. The default emission
factors provided for Tier 1 have been developed from only a few (less than 10) data points only, which may not
be representative for large areas or climate zones. Therefore, a default uncertainty level of +/- 75% of theestimated carbon emission or removal has been assumed based on expert judgement. The uncertainty probability
distribution of the emissions is likely to be non-normal, so the 95% interval of a log-normal distribution isassumed here as default uncertainty (Table 3.5.2). It is good practice to use this range rather than a symmetricalstandard deviation.
The area of drained peatlands is estimated to have an uncertainty of 50% in Europe and North America, but may
be a factor of 2 in the rest of the world. Uncertainty in Southeast Asia is extremely high since peatlands areunder particular pressure, mainly because of urbanisation and intensification of agriculture and forestry, andmaybe also for peat extraction. It is assumed that the data of land conversion to peatland has the same
uncertainty although countries with a predominance of commercial peat extraction will have better data.
Tier 2: Under Tier 2, actual area estimates for land conversion will enable more transparent accounting andallow experts to identify gaps and avoid double counting of land areas. The Tier 2 method uses at least somecountry-defined defaults, which will improve the accuracy of estimates, provided they better represent conditions
relevant to the country. When country-specific defaults are developed, countries should use sufficient sample
sizes and techniques to minimize standard errors. Probability density functions (i.e. providing mean and varianceestimates) should be derived for all country-defined parameters. Such data can be used in advanced uncertainty
analyses such as Monte Carlo simulations. Refer to Chapter 5 of this report for guidance on developing suchanalyses. At a minimum, Tier 2 approaches should provide error ranges for each country-defined parameter.
Tier 3: Under Tier 3, activity data from a land use and management inventory system should provide a basis toassign estimates of uncertainty to areas associated with land conversion. Combining emission and activity data
and their associated uncertainties can be done using Monte-Carlo procedures to estimate means and confidence
intervals for the overall inventory. Process-based models will probably provide more realistic estimates but need
to be calibrated and validated against measurements. Generic guidance on uncertainty assessment for advanced
methods is given in Chapter 5 (Section 5.2, Identifying and Quantifying Uncertainties) of this report. Sincedrainage of peatlands leads to peat compaction and oxidation and carbon losses other than as CO2 the stockchange approach to monitor CO2 fluxes can be imprecise. If used, it should be calibrated with appropriate flux
measurements.

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3.5.2.2

C HANGE IN CARBON STOCKS IN LAND CONVERTED TO
FLOODED LAND (R ESERVOIRS )The method for estimating carbon stock change due to land conversion to flooded land is shown in Equation
3.5.6. As with the method described in the previous section for peatland, this method assumes that the carbon
stock of land prior to conversion is lost in the first year following conversion. The carbon stock of the land prior
to conversion can be estimated following the method for living biomass described for various land-use categories
in other sections of this chapter. In Tier 1, it is assumed that the carbon stock after conversion is zero.
EQUATION 3.5.6
ANNUAL CHANGE IN CARBON STOCKS IN LIVING BIOMASSIN LAND CONVERTED TO FLOODED LAND

∆CLW floodLB = [Σ Ai ● (BAfter – BBefore) i] ● CF
Where:∆CLWfloodLB = annual change in carbon stocks in living biomass in land converted to flooded land, tonnes
C yr-1
Ai = area of land converted annually to flooded land from original land use i, ha yr-1
BBefore = living biomass in land immediately before conversion to flooded land, tonnes d.m. ha-1
BAfter = living biomass immediately following conversion to flooded land, tonnes d.m. ha-1 (default = 0)
CF = carbon fraction of dry matter (default = 0.5), tonnes C (tonnes d.m.)-1
In actuality, it is possible that the carbon remaining on the converted land prior to flooding may be emitted over
several years after flooding. Under Tier 2, this emission process can be modelled. Countries will need to develop
country-specific emission factors and can refer to the discussion of ongoing emissions from flooded landremaining flooded land in Appendix 3a.3 for general guidance on how to implement such a method.
No guidance is provided on carbon stock changes from soils due to land conversion to flooded land at this time.
Emissions of non-CO2 gases from land converted to flooded land are covered in Appendix 3a.3.

3.5.3

CompletenessA complete estimate of emissions from land converted to wetlands should include all land converted to either
peat extraction or flooded land. For organic soils managed for peat extraction, a complete inventory should cover
all land converted to industrial peatlands. It should be consistent with a complete inventory of all industrial
peatlands including abandoned peat mining areas in which drainage is still active, and areas drained for future
peat extraction, but omitting areas reverting to wetland status.

3.5.4

Developing a Consistent Time Series

General guidance on consistency in time series can be found in Section 5.6 (Time Series Consistency and
Recalculation). The emission estimation method should be applied consistently to every year in the time series,
at the same level of disaggregation. Moreover, when country-specific data are used, national inventories agency
should use same measurements protocol (sampling strategy, method, etc.) over time, following the guidance inSection 5.3, Sampling. If it is not possible to use the same method or measurement protocol throughout the timeseries, the guidance on recalculation in Chapter 5 should be followed.
The area of organic soils converted to peat extraction may need to be interpolated for longer time series or trends.
If this is required, consistency checks should be made (i.e., by contacting peat-mining companies), to gather
temporal information about areas affected by former or future peat extraction. Differences in greenhouse gas
emissions between inventory years should be explained, e.g. by demonstrating changes in areas of industrial
peatlands or by updated emission factors.

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3.5.5

Reporting and Documentation

It is appropriate to document and archive all information required to produce the national emissions / removals
inventory estimates as outlined in Chapter 5 of this report subject to the following specific considerations.
Emissions from land converted to peat extraction or flooding have not been explicitly mentioned in the IPCC
Guidelines. They can be reported in using the reporting tables in Annex 3A.2.
Emission factors: Since the literature data are so sparse, the scientific basis of new determinations of emission
factors, parameters and models should be completely described and documented. This includes defining the
input parameters and describing the process by which the emission factors, parameters and models were derived,
as well as describing sources of uncertainties.
Activity data: Sources of all activity data used in the calculations (data sources, databases and soil map
references) should be recorded, plus (subject to any confidentiality considerations) the communication withcompanies dealing with peat extraction. This documentation should cover the frequency of data collection andestimation, and estimates of accuracy and precision, and reasons for significant changes in emission levels.
Emission results: Significant fluctuations in emissions between years should be explained. A distinction should
be made between changes in activity levels and changes in emission factors, parameters and methods from year
to year, and the reasons for these changes documented. If different emission factors, parameters and methods areused for different years, the reasons for this should be explained and documented.

3.5.6

Inventory Quality Assurance/Quality Control(QA/QC)

It is appropriate to implement quality assurance/quality control (QA/QC) checks as outlined in Chapter 5(Section 5.5) of this report, and to conduct expert review of the emission estimates. Given the shortage of data,
these reviews should be conducted regularly to take account of new research findings. Additional quality control
checks, as outlined in Tier 2 procedures in Chapter 8, QA/QC, of GPG2000, and quality assurance procedures
may also be applicable, particularly if higher tier methods are used to quantify emissions from this source
category. Where country-specific emission factors are used, they should be based on high quality experimental
data, developed using a good practice measurement programme, and be adequately documented.
It is, at present, not possible to cross-check emissions estimates from organic soils managed for peat extraction
with other measurement methods. However, the inventory agency should ensure that emission estimates undergo
quality control by:•

Cross-referencing reported country-specific emissions factors with default values and data from othercountries; and•Check plausibility by cross-referencing areas of organic soils managed for peat extraction with data of peatindustries and peat production.

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