Pollutants and greenhouse gas concerned

This sector aims first of all to provide an estimation of CO2 emissions/removals by land by monitoring carbon flows between carbon pools. Other substances are however associated with these carbon flows. The pollutants and greenhouse gases covered by CITEPA's inventories for the LULUCF sector are presented in the table below:

Pollutants concerned Environnemental Effet/Impact
NOx, NMVOCs, CO Acidification, eutrophication, photochemical pollution
CO2, CH4, N2O Enhanced of the greenhouse effect

 

Principles and features of the sector 

Principles

LULUCF aims to monitor carbon flows (living biomass and organic matter in soils). The main flows are due to land use change (ex: croplands converted to settlements), land use (ex: reduced ploughing of croplands) or multifactor long-term dynamics (ex: forest increase). Forest lands are particularly concerned because of the large amounts of carbon stored in trees, leaf litter and soils. Croplands are concerned too because of carbon contained in organic soil matter. However, this sector does not cover emissions due to nitrogen fertilisation, basic fertilisation, livestock, or particulate emissions resulting from tillage which are included in the Agriculture sector.

The two sectors together are referred to as AFOLU (Agriculture, Forestry and Other Land Uses) in the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines as a unique « land sector ».

Usually, this sector in considered as separate from other sectors in several ways:

  • A standalone method: it focuses on monitoring areas (land use and land use change) which differs from the emission sources usually taken into account (consumption or production) as an indicator to calculate the emissions in the other sectors.
  • Standalone results: it comprises emissions (sources) and removals (sinks) at the same time: its net carbon balance is actually negative in France, that is to say it constitutes a carbon sink.
  • Standalone rules: LULUCF has a particular status in international agreements and is governed by specific rules.

 

Land monitoring

Put simply (cf. Figure 1), the LULUCF sector involves dividing up an area into geographical units, within which flows, emissions and removals arising from the different land uses are estimated.

Figure 1: Geographical divisions and estimated carbon flows in the LULUCF sector

Forets Figure1

(Source : CITEPA)

In accordance with IPCC guidelines, emissions are assessed in six main land-use categories:

    • forests: under the Marrakech Agreements (2001) between the Parties to the Climate Convention, a « forest » is defined in France on the basis of the following minimum values:
      • tree crown cover: 10%,
      • surface area: 0.5 ha (below, spinneys and scattered trees are counted in « Grassland »),
      • height of mature trees: 5 m,
      • minimum width: 20 m (below, hedges are counted in « Grassland »).
    • crops: ploughed and cultivated lands as well as agroforestry parcels to which the « forest » definition does not apply;
    • grassland: grass-covered areas either of natural origin or sown more than five years previously (unlike temporary grasslands, which are accounted as croplands); the grassland category also includes woodland or shrub areas to which the « forest » definition does not apply and which are not included in cropland or settlements (e.g. most hedges and spinneys with a wooded area <0.5 ha).
    • wetlands: lands covered or saturated with water during all or part of the year and not included in any of the other categories, except "other Lands";
    • settlements: built-up areas including transport infrastructure and residential zones of whatever size, except those counted in another category. This category may therefore include grasslands or woodlands that are not used mainly as agricultural or forest lands, i.e., parks, gardens and sports grounds, for example.
    • other lands: for example, rocks, uncovered ground, sand, etc.

 

Carbon sources and sinks

Most GHG flows from the LULUCF sector involve CO2 and therefore carbon. The IPCC guidelines on LULUCF define several carbon pools:

  • above-ground living biomass,
  • underground living biomass,
  • deadwood,
  • leaf litter,
  • organic soil matter,
  • twood products.

With regard to inventories, the aim is to determine all carbon flows from the different carbon pools. Figure 2 shows the principle of carbon flows between pools:

Figure 2: Flows between carbon pools in the LULUCF sector

Forets Figure2

(Source : CITEPA)

The net carbon balance in the last few years for the LULUCF sector, as a whole, in France is estimated to be about 50 Mt CO2 per year.

The main carbon flows observed on lands are the result of management practices (forestry and agriculture), major land-use changes (deforestation, settlement) or natural events (storms, fires).

Forests are often the main contributor to flows of CO2 as they can produce flows that are both large and sustained on forest lands. This is the case in France, where forest increment (i.e. tree growth) is currently absorbs more CO2 than the amount of CO2 released by logging and tree mortality. Forest carbon stocks are therefore increasing.

Depending on each case, changes in land use can either release carbon (when forests and grasslands are converted to croplands) or absorb carbon (when grasslands and croplands are converted to forests).

In compiling the inventories, carbon absorption and release can be estimated in different ways depending on the type of conversion or the carbon pool concerned. If a forest is cleared, for example (cf. figure 3), it is considered that the carbon in the biomass is released rapidly, whereas the carbon contained in soil organic matter is released into the atmosphere over a much longer period (20 years).

Figure 3: Diagram showing changes in carbon stocks in the different pools over time after a forest is cleared.

Forets Figure3

(Source : CITEPA)

Data on emission trends for the « LULUCF » sector by sub-sectors are available and downloadable on this website, on the SECTEN inventory page, section « Sub-sector contribution by air pollutant and greenhouse gas ».

The SECTEN report, available free of charge only in online reading on this website for CITEPA members, provides a sector analysis for each pollutant et greenhouse gas to understand the data and the factors influencing the trends observed, inclunding regulatory framework (read the SECTEN report online via your login and password).

Example: En France, depuis 1990, la principale évolution des flux de carbone est liée à la croissance forestière (en surface et en volume) qui engendre un puits croissant de CO2. Cette tendance est néanmoins impactée par les deux épisodes de tempêtes en 1999 (Lothar et Martin) et 2009 (Klaus) qui provoquent à la fois une mortalité et des prélèvements ponctuels et importants et donc diminuent temporairement le puits de la France ... (to read more, consult the SECTEN report online via your login and password).

The pollutants and greenhouse gases inventories made by CITEPA are produced in an objective and impartial manner.

All the methods used to produce those pollutants and greenhouse gases inventories are explained and detailed in the OMINEA report, made by CITEPA. A database including the activity data and the emission factors applied is also available on this website.

These methods, used for the estimation of both pollutants and greenhouse gases, are internationally accepted methods. Concerning the pollutants, the methods applied are consistent with the EMEP methodology, and concerning the greenhouse gases, with the GIEC methodology.

CITEPA is annually audited by international experts (UNFCCC and UNECE) in order to control these methods are properly applied.