Enter the selected criterion as stated in the source document in this space:

Extant Biomass - Biomass represents the mass of living organisms inherent in an ecosystem and is considered a measure of forest ecosystem condition.

The mean annual increment (MAI) is the average net annual increase in the yield (expressed in terms of volume per unit area) of living trees to a given age, and is calculated by dividing the yield of a stand of trees by its mean age. The MAI is dependent on a number of factors, including climate and elevation, soil conditions and forest management practices. MAI is a measure of the net biomass production of the forest and can be used to indicate its productivity. However, production loss due to mortality, insects and diseases is not included; therefore, total growth before losses generally is considerably larger than net growth.

Justify your selection of the Criterion in Box A. Please ensure you discuss its relationship to theory:

This criterion is defined as: "Forest condition over time is a measure of relative freedom from stress (health) and a relative level of physical/biological energy (vitality) within the forest ecosystem. Such an objective is imprecise and the links to ecological theory are not clear. There is confusion in terms, using words like health and vitality, which have no precise meaning. The next sentence defines the criterion as "Biomass represents the mass of living organisms inherent in an ecosystem and is considered a measure of forest ecosystem condition". Surely any particular amount of biomass is not an inherent condition of an ecosystem. The amount of biomass in a forest is a function of many factors. For a given site, if one considers a disturbance such as fire, biomass level will be a function of time since fire, and the intensity of the fire. If the disturbance on the same site were an epidemic insect outbreak instead of fire, the amount of biomass would again be different. Thus the suggested measure of biomass is not an inherent value, but rather a highly variable one.

The indicator suggested for this criterion uses mean annual increment (MAI) as a measure of biomass. MAI is a useful measure of tree growth. As such, it has value for forest volume and future yield assessments and may be a useful economic criterion. However MAI is not an ecosystem based measure as it concentrated on only one element. MAI varies within a site by tree stem density, competition from understory species. MAI is also impacted by fertilization, thinning and other management interventions. Extant biomass of a given area can be very different that tree growth rates. In northern or high altitude forests, extant biomass may be more a function of the depth of soil organic layers or amounts of coarse woody debris.

In non-forest terrestrial ecosystems, there are similar difficulties in using forest biomass as an indicator of forest condition. Above ground biomass in grassland and steppe ecosystems varies by season, herbivore density and other factors. Such variation is very difficult to account for in an assessment program.

The final issue is the relation of extant biomass to sustainability. The data example used for this indicator points illustrates is weakness as a criteria for assessing ecological condition. The only conclusion possible form the data is that softwood trees are long lived (MAI= generally long lived and slow growing (MAI =1.69 m³/ha/yr) and slow growing and popular and birch are short lived and faster growing (MAI = 1.92 m ³/ha/yr). While such basic information is useful in many contexts, it utility as a criterion for assessing sustainability is unclear.

If there is no inherent relationship between ecosystem function and extant biomass, or ecosystem structure and extant biomass, then there is no inherent relationship with ecological integrity or sustainability. Given the tenuous relation to theory and the difficulty of measuring extant biomass, this criterion of sustainability is rejected.

Provide bibliographic references (if any) which support your selection of this Criterion for evaluation:

N/A

Please name (give the reference of) the Criterion that overlap (come closest) to the Criterion that has been selected for evaluation:

CIFOR: -

CIFOR – BAG: -

CCFM: -

Idaho: -

GFE: -

Please record your notes on evaluating the Criterion (Box A) here:

N/A

Identify linkages between Criterion, to ensure that the same or similar information is not collected twice and to ascertain whether the necessary feedback loops exist between Criterion.

Ecological /

Biophysical: -

Social: -

Economic: -

Forest Mngt: -

Yield & harvest: -

Does not fit: -

Final version of Criterion, state only if different to definition in Box A: