Indicator Code: FORGRO
Objective: Ecosystem Vitality
Policy Category: Productive Natural Resources
Subcategory: Forestry
Indicator Short Name: Change in Growing Stock
Indicator Full Name: Change in the Volume of Growing Stock
Indicator Description: Growing stock is defined as the standing tree volume of the forest resources. An increase in growing stock usually means higher quality forests, whereas a decrease in growing stock generally indicates degrading forest conditions. For simplicity in measurement and explanation of the forest resources condition, growing stock is a good choice.
Although growing stock is important, standing tree volume alone is not sufficient for a detailed analysis. For example, future wood supply is highly dependent on the age class distribution, or the stand structures and the management system applied. Further, biodiversity requires diversity, e.g., in tree species and succession stages. Carbon storage is highly dependent on soil carbon, which may not be directly correlated to tree volume. Finally, converting primary forests to forest plantations may increase the tree volume but it generally degrades the condition (related to biodiversity and ecosystems) of the natural habitat.
Units: cubic meters/hectare
Country Coverage: 127 (deforestation data were used to increase country coverage to 230)
Reference Year: 2005:2000
Target: No Decline
Target Source: Expert Judgment
Short Source: Forestry Department, Food and Agricultural Organization of the United Nations
Source: Food and Agricultural Organization of the United Nations. (2005). Global Forests Resources Assessment 2005. Rome, FAO.
Source URL: http://www.fao.org/forestry/site
Methodology: Growing stock is a volumetric measure that measures the cubic meters of wood over bark of all living trees more than X cm in diameter at breast height. It includes the stem from ground level or stump height up to a top diameter of Y cm, and may also include branches to a minimum diameter of W cm. Countries indicate the three thresholds (X, Y, W in cm) and the parts of the tree that are not included in the volume. Countries must also indicate whether the reported figures refer to volume above ground or above stump. The diameter is measured at 30 cm above the end of the buttresses if these are higher than 1 meter. Growing stock includes windfallen living trees but excludes smaller branches, twigs, foliage, flowers, seeds, and roots.
The ratio of growing stock in cubic meters was taken for 2005 and 2000. Ratios greater than 1 indicate that the growing stock increased over the time period, and ratios less than 1 indicate that it decreased. Countries with a growing stock of 1 or greater were taken to be “at target”. Countries with declining growing stock were considered to be below target. For Germany, the ratio of 2000 to 1990 data was used instead.
For countries without growing stock data, data on percent change in forest area were used. The correlation between growing stock and deforestation data is very high (excluding three outliers, Comoros, Indonesia, and Micronesia, the R2 = 0.81, p<.001, ), so thiswas determined to be a robust way to impute the value for change in growing stock.
Additional Citations: not available