6.2.1    Forest environmental services

Forest accounts include three environmental services that do not correspond directly to an economic activity or product as defined in SNA: carbon storage, biodiversity preservation and protective services for water, soil and other ecosystem functions. Other services may be included where relevant.

Carbon storage is compiled in almost all forest accounts because it can be fairly easily estimated and there is reasonable consensus about valuation. Carbon storage is measured using standard conversions of biomass to carbon content. Table 6.5 shows a standard table for carbon content of total woody biomass. This table, like that for standing timber, may be further disaggregated by tree species and other forest characteristics. Additional tables may be constructed for forest ecosystems that include carbon contained in forest soils and other biomass in forests such as ground vegetation and leaf litter.

The natural changes to carbon storage are usually calculated by modelling based on stocks of timber, age and species of tree and other biological parameters. Because of climatic variations, actual change in carbon may vary from one year to the next, so Eurostat has recommended that averages over several years be used. In the Eurostat pilot programme, five countries reported on their experience with carbon accounting using time intervals from opening to closing stock that ranged from four years (Sweden) to nine years (Finland) (Eurostat, 2002b). Countries reported that carbon estimates for standing timber are fairly reliable, but estimates for carbon in other woody biomass (small branches, stumps, etc.) were not as accurate. Given the importance of climate change, it is likely that scientific information and methods for estimation will improve in the future. This will be especially important for developing countries where there has been less research into parameters for forest carbon storage other than standing timber.

Table 6.5:        Carbon balance accounts for woody biomass, Finland (million tons of carbon)

Note: date not given in source document

Definitions of entries in the table are the same as those in the accounts for standing timber.

Source: Adapted from UN et al., 2003, Table 8.20, p. 357

In addition to carbon storage, forests are widely believed to provide other important ecological services:

There is a great deal of debate about the nature and value of these services and very few forest accounts include environmental services other than carbon storage. The impact of land use change on soil and water can only be verified at relatively small scales (tens of kilometres) (FAO, 2002). At larger scales it may be difficult to distinguish the impact of land use change from other processes because of the complexity of the processes at the watershed level and the time lags between change and its impact. The extent of watershed protection services can vary enormously due to site-specific characteristics such as catchment size, topology and the state of land use (Chomitz and Kumari, 1998; FAO, 2002).

The links between forest services to agriculture, hydroelectric power, domestic water supply, etc. are difficult to measure in physical terms and services can vary enormously by site making it difficult to extrapolate from case studies. A recent joint study by the World Bank and WWF International examined the water supply of the world’s 105 largest cities, measured by population (Dudley and Stolton, 2003). The study identified the conditions under which forests may increase or decrease water supply and downstream soil erosion. With respect to regulating water quantity, the role of forests is mixed. However, there was consistent, strong evidence to support the claim that forests make a major contribution to maintaining water quality. Many urban areas rely on watershed protection for at least part of their water supply, especially water quality.

In the Eurostat pilot programme, several countries compiled physical accounts that identify the land area providing protection services, as shown in Table 6.6.

Table 6.6:        Wooded land providing environmental protective services in France, 1990‑1999 (1000 hectares)

Na: Not applied

Source: Eurostat, 2002b, Table 26, p.38

It is not possible to measure biodiversity conservation services directly, so indicators are derived based on species counts and protection status of wooded land, as shown in Tables 6.7 and 6.8. The species categories are usually further disaggregated, and a table is compiled for a reference year and one for the most recent year.

Table 6.7:       Indicator of biodiversity: forest-occurring species at risk or endangered in Sweden, 2000

Note: The IUCN categories of species facing a high risk of extinction in the wild in the near future are defined as CR= critically endangered, EN= endangered, VU = vulnerable.

Source: Adapted from Eurostat 2002b, Table 16, p. 29

Table 6.8:        Protection status of wooded land in Sweden, 1993-1998 (1000 hectares)

Note: IUCN categories are:

I.      Strict nature reserve, wilderness area
II.      National park
III.     Natural monument
IV.    Habitat/species management area

Source:  Based on Eurostat 2002b, Table 14, p. 27

6.3 Supply and use table for forest products

The most detailed account for flows of goods and services is provided by the supply and use table (SUT). SUT shows the origin of different forest products, the processing of raw forest products into other products such as sawnwood and firewood, and the use of each product by every sector of the economy as well as final users (households, government, capital formation and exports). National accounts provide monetary SUTs for forest products. The forest accounts of SEEA provide the corresponding physical SUTs and, in principle, extend SUTs for non-timber forest products as well. The two tables are linked to each other and the rest of the economy through the use of a common classification for industries and commodities. From these tables, commodity balances for forest products may be constructed, as well as an input‑output (IO) table or SAM in which the production of forest products is represented in physical terms.

Table 6.9 shows the framework for the supply and use of nine different wood products, including two waste products, NTFP and forest services in physical units. Wood products are measured in thousands of cubic metres, NTFP in tons and forest services in various physical units, as described in the previous section. The supply table shows the main forest products and the industries that provide them. Standing timber is provided only by the forestry and logging industry; all other products can be supplied by a number of industries, or imported. Total supply equals domestic output plus imports.

The use table shows the use of forest products as intermediate inputs to industry and use by final users, households, government, exports and capital formation. The intermediate use of wood products is concentrated in several related industries: forestry, manufacture of wood products, pulp, paper, printing and recycling. Final consumption is generally restricted to three products: firewood, manufactured wood and wood products such as furniture or construction timber, and paper. Any product except standing timber may be exported. Only standing timber and certain manufactured wood products are treated as capital goods.

In principle, these detailed supply and use tables may be extended to include other, non-timber forest products. In practice, however, such extensive tables are often created only for wood products because of limited data about the use and transformation of non-timber forest goods and services. The forestry SUT for France shown in Table 6.9 includes only wood and wood products.

Table 6.9:    Physical supply and use table for wood products, France, 1999

(timber, logs and wood in 1000 cubic metres; pulp, paper and waste in 1000 tons)

Source: Eurostat 2002a, Table 61, p. 65