6.3 Quantification

corresponds to 2.5.6 NCS

Forests are greenhouse gas reservoirs (carbon reservoirs). They can be both sources and sinks of greenhouse gases.

Relevant greenhouse gas reservoirs in the forest:

• Above-ground living biomass (trees, shrubs, ground vegetation)

• Below-ground living biomass (roots of trees, shrubs, ground vegetation)

• Dead wood (from trees and shrubs, standing and lying) 10-30% of total biomass

• Litter layer (partially decomposed biomass lying on the ground)

• Soil carbon (mineralised C-part in the soil)

In principle, all greenhouse gas reservoirs can be taken into account by measuring or estimating them using reliable models. For reasons of practicality, non-tree biomass, dead wood, litter layer and soil carbon can be omitted. This is conservative, as these reservoirs are aligned with the wood stock or negligible in quantity (above-ground non-tree biomass, ground vegetation).

Greenhouse gas emissions e.g. from burning of slash, soil cultivation, artificial fertilisers, and emissions from the decomposition of nitrogen-fixing species cannot be identified as caused by the project. These emissions, which are linked to wood utilisation and stand establishment, tend to decrease due to project activities (reduced wood utilisation). Therefore, it is conservative that such emissions are not considered as reference or project emissions for the method.

The reservoir (wood stock) is influenced by the following dynamic parameters:

• Utilisation (Source)

• Growth (Sink)

• Mortality / Risk (source)

6.3.1 Carbon Sources, Sinks and Reservoirs Controlled by the Project Owner

The main C-reservoir is the living tree biomass, directly influenced by the project owner through wood utilisation. The wood inventory is determined by conventional recognised methods of forest inventory or stock estimation. It is then inferred to the biomass of the entire tree using the relevant conversion factors.

Yield and stock models always refer to the living wood stock (above-ground). There are corresponding conversion factors (Root to shoot ratio, Biomass Expansion Factors BEF, e.g. Ref. 06) for converting from living standing wood stock to whole tree biomass. The wood stock and the wood utilisation are recorded using conventional inventories and conventional measurement methods. Both data sources are converted to living tree biomass.

Project emissions are emissions of greenhouse gases generated by the project, such as harvesting or planting operations, construction and maintenance of roads, transportation, planning and control trips by the forester as well as biodiversity measures. These emissions are lower or at most equal to those of conventional management with adjusted cultivation.

Therefore, the project emissions in this methodology are conservatively assumed to be zero.

6.3.2 Carbon Sources, Sinks and Reservoirs Related to the Climate Protection Project

The non-tree biomass (shrubs, ground vegetation, litter) can be credited if recognised methods are applied for determination. The non-tree biomass can also be omitted. This is conservative because the amount is negligible compared to the tree biomass.

Dead wood can account for a significant proportion of the biomass in near-natural forest stands. The proportion of dead wood increases with the age and timber stock of the forest stands, often due to prolonged non-utilisation. The stock of dead wood is aligned with the standing living wood stock. The decomposition is very slow. Thick trunks do not completely decompose over the project duration. If recognised methods for measuring or estimating the volume of dead wood are applied, this C-reservoir can be credited in the project. It is conservative not to consider dead wood in the project.

Soil Carbon

In temperate zone forests, soil carbon accounts for half to two-thirds of the total carbon (Ref. 27, 40, 54, 65 cited in Ref. 64). There is a certain underestimation due to the fact that more C is stored under large trees than between the trees (Ref. 59). Soil C is usually measured between the trees. In natural forests, carbon continues to accumulate in the soil over centuries Ref. 28. A literature review on this can be found in Ref. 66 taking into account Ref. 58, 59, 60, 61, 67.

In the soil of normal sites, there is about the same amount of carbon as in the living biomass (Ref. 10, 40). For every tonne of CO₂ sequestered in the trees, another tonne is expected in the soil. The reservoir is aligned with the living biomass. Soil carbon is, however, only measurable in the laboratory with an effort hardly justifiable at an operational level. Furthermore, soil carbon responds slowly to management measures (Ref. 27, 35). Soil carbon can be fully credited if recognised methods for recording and monitoring are used. It is conservative not to consider soil carbon in the project.

6.3.3 Determination of the Living Tree Biomass from the Wood Stock (Reservoir)

Recognised methods of wood stock inventory are applied, generally on a sample basis with defined accuracy for tree species and/or species groups. The inventory procedures at different times must be identical or conservative towards each other to avoid overestimations of the sink performance. For sample inventories, a maximum standard error of 5% with a 95% confidence interval is permissible. If the error is higher, the difference to 5% must be considered in the project assumptions. This inventory error can be calculated using permanent sample inventories, two-phase inventories, and inventories with synthetic estimators. Other inventory methods must be able to provide a comparable, traceable accuracy statement. If no inventory data is available and estimation methods are used, the assumptions must be made conservatively to exclude an overestimation of the sink performance. The standing wood stock is measured in cubic meters of merchantable wood, distinguished by tree species or species groups. The standing wood stock in m3 is converted into tCO₂e of the living tree biomass using recognised conversion procedures.

Other relevant reservoirs can be credited, provided they are quantified using recognised methods and conservatively converted to tCO₂e.

Schematic conversion of harvested wood into CO2e according to Ref. 6 (adapted)

In general, national conversion factors are used (cf. country modules). If such fundamentals are not available, alternative relevant conversion factors are used, such as REF Guidelines2006V4_04_Ch4_Forest_Land.pdf

6.3.4 Determination of Utilisation (Source)

The utilisation can be determined in one of the following two ways:

1. Wood utilisation is measured standing in m3. The same conversion procedures from m3 to tCO₂e as for the stock can be used. Recognised procedures are used (Grouping at 1.3 Metres height, using a recognised volume tariff). Supplementary estimates are to be handled conservatively.

2. Wood utilisation is measured after harvesting (harvest volume in laid measure, harvester measure, mill measurement, estimates): the volume is fully recorded. Estimates are to be assumed conservatively. Harvest losses are additionally taken into account.

In general, national conversion factors are used (cf. country modules). Recognised estimation and calculation methods are applied to deduce from the harvested volumes in m3 to the standing harvest volume in m3 and from there to tCO₂e. The conversions should be conducted conservatively. Harvested wood enters the calculation as a CO₂ source.

6.3.5 Determination of Growth (Sink)

The growth can be determined in two ways:

1. The growth is derived from subsequent inventories.

2. The growth is estimated.

To 1. The growth is derived from successive inventories (stock change method): (Two stocks are summarised and compared. Utilisation and mortality are taken into account. The difference directly results in the sink performance.

To 2. growth is derived from models: Yield table models or other growth models provide the site quality for tree species based on the natural site assuming certain management concepts. Yield table models indicate growth in cubic meters of inventory (Vfm) or harvest cubic meters (Efm). Back-calculation to tCO₂e is done conservatively using recognised factors.

6.3.6 Quantitative Determination of Sink Capacity

The method basically follows the formulas of the AR CDM Method AR-AMS0001. IPCC 2006, GL for AFOLU (Ref. 12)

The formulas of the CDM methodology are used as follows:

• Reference scenario (Baseline): Equation 1

• Baseline Sink: Equation 10

• Recognised conversion factors BEF are used for converting wood stock into biomass of living trees. Equations 2-9, 15 and 16 are therefore not applied. The national biomass expansion factors BEF take into account the total tree biomass and not just the above-ground. The variable for the (root to shoot ratio) is therefore not applied.

• Equations 11-14 are used for the ex-ante calculation of the sink performance. Equations 17 and 18 are used.

• Leakage is assumed to be zero, therefore Equation 19 is applied. The conditions for this should be noted in Chap. 6.5.

• The total net sink performance is calculated according to Equation 21.

• The VER are time-limited to the monitoring period, equations 22 and 23 are not applied.

• Equations 24, 29, 35 and 36 are applied for ex-post calculations. The remaining equations are not relevant due to the use of recognised conversion factors.

6.3.6.1 Determination of the Reference Scenario (Baseline)

Carbon Reserves in the Reference Scenario

In Equation 1 according to Tool, above-ground and below-ground biomass are added together. Using the BEF makes this unnecessary.

Equation 1: $\Delta C_{\mathit{BSL},t} = (B_{(t)} - B_{(t-1)}) \cdot \frac{44}{12}$

corresponds to Equation 10 in AR CDM Method AR-AMS0001, where

$\Delta C_{\mathit{BSL},t}$ = C - Stock change in the baseline scenario (without project) in year t (tCO₂/a) = Net greenhouse gas sink or source in the baseline scenario in year t (tCO₂/a)

$B_{(t)}$ = C - stock in the reference scenario (without project) in year t (tC)

$B_{(t-1)}$ = C - stock in the reference scenario (without project) in year t-1 (tC)

$\frac{44}{12}$ = $\frac{CO_{2}}{C}$

Example: Duration 30 years,\nStock of the reference scenario at the start of the project (Baseline): $B_{(t0)}$ = current stock

Target stock of the reference scenario (Baseline): $B_{(t30)}$ = Normal stock from ET or other literature

Normal stock: Derived in detail or summarily from tree species, or species group and site quality, or conservatively estimated.

Assumed Sink Performance of the Reference Scenario

The target stock and thus the intended sink performance can be chosen within the silvicultural and legal framework. This is a decision of the owner, which must be coordinated with other operational objectives. Starting from the stock at the beginning of the project, it is adjusted linearly over the project duration to the target stock at the end of the project.

6.3.6.2 Determination of the Project Scenario in the Managed Forest (ex-ante)

Equation 2 states that the C-stocks of the project scenario at the start of the project ($t=0$) must be as high as the C-stocks of the reference scenario ($t=0$).

Equation 2: $N_{(t=0)} = B_{(t=0)}$

corresponds to Equation 11 in AR CDM Method AR-AMS0001, where

$N_{(t=0)}$ = C-stock at time t=0 in the project scenario (tC/ha)

$B_{(t=0)}$ = C-stock at time t=0 in the baseline scenario (tC/ha)

Equation 3: $N_{(t)} = \sum\limits_{i=1}^{l} (N_{A(t)i} + N_{B(t)i}) \cdot Ai$

corresponds to Equation 12 in AR CDM Method AR-AMS0001, where

$N_{(t)}$ = C-stock at time t in the project scenario (tC)

$A_{i}$ = Area of stratum (i) (ha)

$N_{(A(t)i)}$ = Aboveground C-stock (tC)

$N_{(B(t)i)}$ = Belowground C-stock (tC)

Biomass expansion factors (BEF) are used instead of $N_{(A)}$ and $N_{(B)}$.

Assumed Gross Sink Performance of the Project $\Delta C_{\mathit{PROJ},t}$

Equation 4: $\Delta C_{\mathit{PROJ},t} = (N_{(t)}-N_{(t-1)}) \cdot \frac{44}{12} \Delta {t}$

corresponds to Equation 17 in AR CDM Method AR-AMS0001, where

$\Delta C_{\mathit{PROJ},t}$ = Project Gross Greenhouse Gas Sink (tCO₂/a)

$N_{(t)}$ = C-stock at time t in the project scenario (tC)

Estimated project emissions $\text{GHG}_{\mathit{PROJ},t}$

Project emissions are assumed to be zero. The conditions for this are mentioned in Chap. Mentioned and to be observed in 6.3.1.

Equation 5: $\text{GHG}_{\mathit{PROJ},t} = 0$

where

$\text{GHG}_{\mathit{PROJ},t}$ = Project emissions in year t (t CO₂/a)

Estimated External Effects (Leakage)

Leakage is assumed to be zero. The conditions for this are in Chap. Chap. 6.5 and should be noted.

Equation 6: $L_{t} = 0$

where

$L_{t}$ = Leakage in year t (tCO₂/a)

Actual sink performance in the project scenario (ex-ante)

The difference between the reference scenario and the project scenario gives the actual sink performance:

Equation 7: $\text{ER}_{t} = \Delta C_{\mathit{PROJ},t} - \Delta C_{\mathit{BSL},t} - \text{GHG}_{\mathit{PROJ},t} - L_{t}$

corresponds to Equation 21 in AR CDM Method AR-AMS0001, where

$\text{ER}_{t}$ = Net creditable sink performance in (tCO₂/a)

$\Delta C_{\mathit{PROJ},t}$ = Gross greenhouse gas sink in the project scenario in year t (tCO₂/a)

$\Delta C_{\mathit{BSL},t}$ = Net greenhouse gas sink or source in the reference scenario in year t (tCO₂/a)

$\text{GHG}_{\mathit{PROJ},t}$ = Project emissions in year t (tCO₂/a)

$L_{t}$ = Leakage in year t (t CO₂/a)

6.3.6.3 Determination of sink performance in managed forest (ex-post)

In managed forests, the sink performance (emissions reduction) is determined ex-post. The validation method focuses on the wood stock, which is converted into living tree biomass. Omitting other carbon reservoirs (soil, etc.) is conservative.&#x20

Calculation of sink performance ex-post

Equation 8: $ER_{total,t} = V_{t} - B_{t} - L$

The sink performance $ER_{total}$ is divided into the sink performance "removal" $ER_{removal}$ and "conservation" $ER_{conservation}$. For this, $ER_{total,t} = ER_{removal,t} + ER_{conservation,t}$

The sink performance $ER_{removal}$ can be determined in two ways:

1. Stock change method (Stock Change):

&#x20Equation 9: $ER_{removal,t} = V_{t} - V_{t0} - L$

1. Growth/Loss method (Gain - Loss):

Equation 10: $ER_{removal,t} = \sum\limits_{t=1}^{n}(\frac{n}{t}) z - \sum\limits_{t=1}^{n}(\frac{n}{t}) N- \sum\limits_{t=1}^{n}(\frac{n}{t})M-L$

The following baseline applies to Equations 9 and 10: $B_{removal,t} = V_{t0}$

The sink performance $ER_{conservation}$ is determined as follows. For this: $V_{t} <= V_{t0}$

Equation 11: $ER_{conservation,t} = V_{t} - B_{conservation,t} - L$

Here are:

$ER_{t}$ = C-sink performance at time t (tC) of type removal, or conservation

$V_{t}$ = C-stock at time t (tC)

$V_{t0}$ = C-stock at time 0 (tC)

$B_{removal,t}$ = C-stock in baseline scenario removal at time t (tC)

$B_{conservation,t}$ = C-stock in baseline scenario conservation at time t (tC)

$z$ = Growth (tC)

$N$ = Utilisation (tC)

$M$ = Mortality (tC)

$L$ = Leakage = 0 (tC)