Forest: growing stock, increment and fellings

Indicator definition

Growing stock in forest and other wooded land, classified by forest type and by availability for wood supply, and balance between net annual increment and annual fellings of wood on forest available for wood supply.

Units

ratio fellings to increment (5)
utilisation rate (%)

Policy context and targets

Context description

Growing stock is one of the basic statistics of any forest inventory and useful for various purposes. The standing volume of growing stock can by applying biomass expansion factors be converted into estimates of above and below-ground woody biomass. Data on growing stock, increment and fellings are crucial for the calculation of carbon budgets in the forest sector.

Relation of the indicator to the focal area

The balance between increment and fellings highlights the sustainability of timber production over time as well as the current availability and the potential for future availability of timber. For a long-run sustainability the annual fellings must not exceed the net annual increment.

An increase in the growing stock, relative to forest area, is an indication of maturing forests. The balance between the growth and felling in production forests is the best indicator to understand both potential for wood production possibilites, and conditions of biodiversity, health, recreation and other functions of forests. The quality of this indicator with regard to biodiversity would improve considerably if suggestions for improvements (see below) would be implemented.

Targets

EU 2020 biodiversity target 3

Related policy documents

• EU 2020 Biodiversity Strategy
  in the Communication: Our life insurance, our natural capital: an EU biodiversity strategy to 2020 (COM(2011) 244) the European Commission has adopted a new strategy to halt the loss of biodiversity and ecosystem services in the EU by 2020. There are six main targets, and 20 actions to help Europe reach its goal. The six targets cover: - Full implementation of EU nature legislation to protect biodiversity - Better protection for ecosystems, and more use of green infrastructure - More sustainable agriculture and forestry - Better management of fish stocks - Tighter controls on invasive alien species - A bigger EU contribution to averting global biodiversity loss

Methodology

Methodology for indicator calculation

Definition of terms:

Growing stock:

The living tree component of the standing volume.
The standing volume refers to the volume of standing trees, living or dead, above-stump measured overbark to top (0 cm). Includes all trees with diameter over 0 cm diameter breast height (d.b.h. -- typically at 130 cm above stump). Includes: tops of stems, large branches, dead trees lying on the ground which can still be used for fibre or fuel. Excludes: Small branches, twigs and foliage. (UNECE/FAO (2000)).

Gross annual increment:

Average annual volume of increment over the reference period of all trees, measured to a minimum d.b.h. of 0 cm. Includes: the increment on trees which have been felled or die during the reference period (UNECE/FAO (2000)).

Net annual increment:

Average annual volume over the given reference period of gross increment less that of natural losses on all trees to a minimum diameter of 0 cm (d.b.h.) (UNECE/FAO (2000)).

Annual fellings:

Average annual standing volume of all trees, living or dead, measured overbark to a minimum diameter of 0 cm (d.b.h.) that are felled during the given reference period, including the volume of trees or parts of trees that are not removed from the forest, other wooded land or other felling site. Includes: silvicultural and pre-commercial thinnings and cleanings left in the forest; and natural losses that are recovered (harvested) (UNECE/FAO (2000)).
Various methods exist in countries to estimate fellings. Fellings are measured from the standing trees, already felled trees, at factory gates, or a combination of techniques. Typically a problem is posed by estimates of fellings for energy and especially the fraction of fellings for domestic firewood. Another issue in some countries is illegal logging and ranges for the volume of illegally felled wood is difficult to assess and with a large error margin.
Combined with forest scenario modelling, it is also possible to create cautious outlooks into the future development of this indicator. Such data are developed under auspices of UN-ECE/FAO as part of its European Forest Sector Outlook Studies (formerly: European Timber Trends Studies).

Measurement units for growing stock:

Status: m³.
Changes: m³/yr.
Status: m³/ha.
Changes: m³/ha/yr.

Measurement units for increment and fellings:

Status: m³.
Changes: m³/yr.

Methodology for gap filling

N/A

Methodology references

• status based on national forest inventories FBI 2003 (Forest biodiversity indicators in the Nordic countries)
• Terms and definitions (Final version) FRA 2005 (Global forest resources assessment update) (2005). FAO Forestry Department. Rome, 2004
• Terminology of Forest Management. Terms and Definitions in English IUFRO (2000). IUFRO World Series Vol. 9-en. IUFRO Secretariat Vienna. SilvaTerm Database.
• Forest resources in Europe 1950-1990 Kuusela, K. 1994. Cambridge University Press.
• TBFRA Supplementary Enquiry for Data on Protected and Protective Forests and Other Wooded Land MCPFE (2000). MCPFE and UNECE, Geneva.
• MCPFE Assessment Guidelines for Protected and Protective Forest and Other Wooded Land in Europe as adopted by the MCPFE Expert Level Meeting MCPFE (2002). 10-11 June 2002, Vienna, Austria.
• Communication from Mr. Almunia to the members of the Commission SEC(2005) 161 final. Sustainable Development Indicators to monitor the implementation of the EU Sustainable Development Strategy.
• Forest Resources of Europe, CIS, North America, Australia, Japan and New Zealand (TBFRA 2000) UNECE/FAO (2000). Main report. UNECE/FAO Contribution to the Global Forest Resources Assessment 2000. United Nations, New York and Geneva.
• Global Forest Resources Assessment 2005 UNECE/FAO (2005). Data for Europe, United Nations, New York and Geneva.
• State of Europe's Forests 2003 MCPFE (2003). The MCPFE Report on Sustainable Forest Management in Europe. Jointly prepared by MCPFE Liaison Unit Vienna and UNECE/FAO. Vienna.

Uncertainties

Methodology uncertainty

No uncertainty has been specified

Data sets uncertainty

No uncertainty has been specified

Rationale uncertainty

MAIN DISADVANTAGES OF THE INDICATOR

• Growing stock, increment and fellings have only indirect linkages to biodiversity, but these linkages are strong especially when considered relative to the forest area. The balance between fellings and increment is primarily an indicator for long-term sustainability of use of woody forest resources and of forest cover. If fellings are lower than increment - which at present generally is the case in Europe - this indicates that forest volume is increasing and probably also that forests are getting older before felling, both indications to be interpreted as beneficial to forest species adapted to more mature forest stages.
• The indicator should be interpreted carefully, for example fast-growing non native species, fertilisation etc. may contribute to increase in growing stock, but may also be detrimental to biodiversity.

ANALYSIS OF OPTIONS

The 35 MCPFE quantitative indicators (http://www.mcpfe.org/documents/r_2007/ici) all relate to sustainable forestry management. From this set, those with most direct relevance to biodiversity were selected.

Forest certification was discussed as a possible indicator for sustainable forest management. Although there is a close connection between criteria and indicators and forest certification, i.e. both are promoting sustainable forest management, forest certification was not selected as indicator of area of sustainable managed forest. Certification is a voluntary, market driven tool, an assurance of conformity with a set of agreed standards, and does not suit long-term monitoring of changes in the forest. Moreover, it is restricted to multipurpose and plantation forests. Even non-certified forests could be sustainable managed.