6.3 Quantification
Last updated
Last updated
corresponds to 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, soil vegetation)
Below-ground living biomass (roots of trees, shrubs, soil vegetation)
Deadwood (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 component in the soil)
In principle, all greenhouse gas reservoirs can be considered by measuring or estimating them through reliable models. For reasons of practicability, the non-tree biomass, deadwood, litter layer, and soil carbon can be omitted. This is conservative because these reservoirs are aligned with the wood stock or negligible in amount (above-ground non-tree biomass, soil vegetation).
Greenhouse gas emissions, for example. from burning of logging residues, tillage, artificial fertilizers, and emissions from the decomposition of N-binding species cannot be identified as caused by the project. These emissions, associated with 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 baseline or project emissions for the method.
The reservoir (wood stock) is influenced by the following dynamic parameters:
Utilisation (source)
Growth (sink)
Mortality / Risk (source)
The main C reservoir is the living tree biomass, which is directly influenced by the project owner through wood utilisation. The wood stock is conservatively assumed to be the normal stock. determined. It is then inferred to the entire tree biomass using the relevant conversion factors.
Yield and stock models always refer to the living wood stock (above ground). For the conversion from the living standing wood stock to the biomass of the entire tree, there are corresponding conversion factors (root to shoot ratio, Biomass Expansion Factors BEF, e.g. Ref. 06).
Project emissions are emissions of greenhouse gases generated by the project, such as harvesting or planting work, construction and maintenance of roads, transport, planning and control trips by the forester as well as biodiversity measures. These emissions are lower or at most equal to those of normal management when adapted management is applied. In forest reserves, most of these emissions are eliminated because no harvesting takes place.
Therefore, project emissions in this methodology are conservatively assumed to be zero.
Non-tree biomass (shrubs, soil vegetation, litter layer) is not accounted for in natural forest reserves. Non-tree biomass is negligible in comparison to tree biomass.
Deadwood can constitute a significant portion of the biomass in natural-like forest stands. The proportion of deadwood increases with the age and wood stock of the forest stands, often due to many years of non-utilisation. The stock of deadwood is aligned with the standing living wood stock. Decomposition is very slow. Over the project duration, thick trunks do not rot completely. It is conservative not to consider deadwood in the project. In natural forest reserves, deadwood is not accounted for.
In forests of the temperate zones, soil carbon accounts for half to two-thirds of the total carbon (Ref. 27, 40, 54, 65 cited in Ref. 64). A certain underestimation results from the fact that more carbon is stored under large trees than between the trees (Ref. 59). Usually, the soil carbon between the trees is measured. In addition, 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 considering Ref. 58, 59, 60, 61, 67.
On normal sites, there is about the same amount of carbon in the soil as in the living biomass (Ref. 10, 40). For every tonne of CO₂ bound in the trees, another tonne is to be expected in the soil. The storage is aligned with the living biomass. The soil carbon is not considered in the project.
Recognised methods of wood stock inventory are applied, usually on a sample basis with defined accuracy for tree species and/or tree species groups. Inventory procedures at different times must be identical or conservative to each other to avoid overestimations of sink capacity. A standard error of no more than 5% is allowed for sample inventories with a confidence interval of 95%. 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 procedures must be able to provide a comparable and traceable accuracy statement. If no inventory data is available and estimation methods are used, the assumptions must be made conservatively so that an overestimation of sink capacity can be ruled out. The standing wood stock is measured in cubic meters of coarse wood, separated by tree species or tree species groups. The standing wood stock in m3 is converted into tCO₂e of living tree biomass using recognised conversion procedures.
Other relevant reservoirs can be accounted for, provided they are recorded with recognised methods and conservatively converted into tCO₂e.
In natural forest reserves, the normal stock is assumed as the initial stock. 
As a rule, national conversion factors are used (see country modules). If no such basis is available, other applicable conversion factors are used, such as REF Guidelines2006V4_04_Ch4_Forest_Land.pdf
Wood utilisation is omitted in natural forest reserves. It is therefore omitted. 
Growth can be determined in two ways:
Growth is derived from successive inventories.
Growth is estimated.
In 1. growth is derived from follow-up inventories (stock change method): summarily, two stocks are compared. Utilisation and mortality are taken into account. The difference directly indicates the sink capacity.
In 2. growth is derived from models: Yield table models, or other growth models indicate the productivity by tree species based on the natural site, assuming certain management concepts. Yield table models indicate growth in cubic meters of stock (Vfm) or cubic meters of harvest (Efm). The conversion back to tCO₂e is performed conservatively with recognised factors. For natural forest reserves, the assumptions according to chap. 6.3.6.3.
The baseline scenario corresponds to the normal stock, which depends on the tree species, productivity, and rotation period. The project scenario can consist of partial scenarios (operational classes, tree species, etc.). 
This project type involves the complete abandonment of wood utilisation on a defined area to promote biodiversity and allow all developmental phases of natural forest evolution (natural forest reserve).
The method applies to areas whose owners commit to protecting them in accordance with MCPFE categories 1.1 or 1.2.
International forest protection area types according to MCPFE (Ministerial Conference on the Protection of Forests in Europe):  
1.1
No active intervention
• Public access restricted • Non-destructive research permitted
Strict nature reserve, etc.
1.2
Minimum intervention
• Game regulation • Forest protection measures • Fire fighting • Non-destructive research • Subsistence use by local population • Safety pruning along roads
Natural forest reserves, process protection areas, refuges, old-growth islands, etc.
1.3
Conservation through active management
Habitat promotion, special forest reserves, etc.
The following assumptions are made for the calculation of reference development (managed forest) and project development in the natural forest reserve:
Assumption 1: The stock doubles from "normally" managed forest to natural forest.
If corresponding data are available, the calculations are performed as in chap. 6.3 (analogous to IIFM project type) applied. Model assumptions can also be used to determine the sink effect in natural forest reserves. In natural forests, at least twice as much carbon is contained as in managed forests (Ref. 66, referring to Ref. 14, 25, 57, 58, 60, 62, 63, 67).
Management removes the stock-rich and long-lasting optimal and decay phases from the forest. The decay phase is particularly rich in biodiversity. A forest reserve is always a carbon sink for a certain period of time. The doubling of the biomass stock is shown by Korpel Ref. 14 as well as Prusa Ref. 25 (Table 96, page 555). In sustainably managed forests, growth and utilisation balance each other, while in natural forests, it is growth and decay. Both are dynamic equilibrium states of biomass stock over larger areas, but at very different levels.
This one-time increase in the average biomass stock is defined as a sink project. This is conservative, because in Central Europe, natural forests in wood stock equilibrium continue to store carbon primarily in the soil (Ref. 28). Recent research suggests that ancient forests of the temperate zones remain sinks, even beyond the supposed equilibrium state (Ref. 28, 55). The further accumulation of carbon takes place mainly in the soil. Recent research also shows that the soil carbon content is higher directly under trees than between them, where it is usually measured. This implies a tendency to underestimate soil carbon. In temperate zones, soil carbon on normal sites (conservatively) is roughly equivalent to that of living biomass. 
Assumption 2: The forest type (natural forest community) determines the site quality and the average normal stock.
Recognised model values of stockholding are applied as a reference scenario, such as the mean timber stock of the normal management class, weighted according to sites and derived from yield tables. The project generates the average stock of the natural forest, which is twice as high. The difference is the sink effect in the project's tree biomass. The application of yield tables is conservative, as the yield level of the growth models from the 1960s and 1970s yield tables has significantly increased (up to 40% in spruce, up to 20% in beech Ref. 09). The stock development typically occurs within 40 years. This stock development is distributed linearly over the 40 years. 
The conversions from the standing stock to the tCO₂e are made according to chap. 6.3.6.
Stock Change Approach for Ex-ante Calculation of Sink Performance The methodology is fundamentally a stock change approach. An average carbon stock without project is compared with an average carbon stock with project (living tree biomass).
The sink performance is calculated as follows: 
according to Korpel applies (Assumption 1): 
For all i = average site quality, it applies:
They are:
= sink performance in tCO₂
= average stock of a natural forest in tCO₂, project case
It applies: =
= average stock of a sustainably managed forest (normal stock) in tCO₂, baseline
It applies: =
= project area in ha
i = site type defined by the site quality and tree species/tree species group
  = Biomass Expansion Factor [tCO₂/m3)
= Project area in ha
=
