APPENDIX 7 - DETAILS OF EMPIRICAL STUDIES REVIEWED IN THIS REPORT
This appendix provides summary descriptions of the forestry accounting studies reviewed in Chapter 4. It presents the studies in chronological order. It focuses on studies that attempt to link forestry accounts explicitly to national income accounts.
Although we attempted to identify and review all existing studies, in the end we were unable to obtain copies of several that we identified, including da Motta (1993) for Brazil, Kong and Naihui (1993) for China, Solberg and Svendsrud (1992) for Norway, and Adger (1993) for Zimbabwe. Undoubtedly, we did not identify all studies, given the tendency of the studies to be published in the gray literature.
Unless otherwise indicated, net accumulation estimates mentioned in the descriptions were negative, indicating a decline in asset value.
Global
Reference: World Bank (1997).
Period: 1970-93 (net accumulation), 1994 (valuation of stocks).
Scope: Subsoil assets, cropland, and pasture land, in addition to forest resources.
Forest resources: Roundwood, nontimber benefits, protected areas.
Links to national accounts: (i) Current accounts—Added net accumulation of roundwood resources to net domestic savings (gross domestic investment minus net foreign borrowing minus depreciation of human-made capital). (ii) Asset accounts—Calculated asset value of forests for timber and nontimber benefits, and also asset value of protected areas, and compared them to values for other natural capital, human-made capital, and human capital.
Physical accounts: For net accumulation, compiled data on roundwood harvest and natural growth, and set net depletion equal to the difference between harvest and growth. For asset valuation, used preceding data as well as data on forest area and protected area.
Valuation: (i) Calculated net accumulation of roundwood by net price method: multiplied net depletion times average stumpage value (weighted average price of logs and fuelwood minus average logging cost). Set net accumulation equal to zero if net depletion was negative (growth exceeded harvest). (ii) Calculated asset values by present value method. For roundwood, if growth exceeded harvest (which implies that harvest can be sustained indefinitely), multiplied harvest times average stumpage value and divided by the discount rate (4 percent). If harvest exceeded growth, treated forest as a mine and capitalized the product of roundwood harvest and average stumpage only up until the projected date of exhaustion. For nontimber benefits, divided forest area by ten (on the assumption that one-tenth of forest generated significant nontimber benefits), multiplied by $112 per hectare in developing countries and $145 per hectare in developed countries, and divided by 4-percent discount rate. For protected areas, multiplied area times asset value of one hectare of pasture land, the assumed minimal opportunity cost of protection.
Official status: Study conducted by the Indicators and Environmental Valuation Unit of the World Bank’s Environment Department, for the Rio + 5 process.
Additional comments: Heavily revised update of World Bank (1995). Covered nearly 100 countries. Concluded that the asset value of forests (for timber, nontimber benefits, protected areas) was smaller than the asset values of both cropland and subsoil assets in most cases. Asset value of timber production was, on average, 3-10 percent of the total value of natural capital (depending on country income class); corresponding figures were 2-5 percent for nontimber benefits and 2-11 percent for protected areas. In general, forest values as a percentage of natural capital were higher in countries in higher income classes.
Asia
Reference: Vincent and Castaneda (1996).
Period: 1970-92.
Scope: Subsoil assets and agricultural soils, in addition to forest resources.
Forest resources: Roundwood in natural forests and plantations.
Links to national accounts: (i) Current accounts—Added net accumulation of roundwood resources to gross domestic savings. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Pertained to growing stock, not forest area. Compiled data on roundwood growing stock (gross volume in all living trees with DBH ≥ 10 cm) and roundwood harvest. Defined "timber depletion coefficient" as ratio of change in stock between 1980 and 1990 (years of FAO forest inventories) to cumulative harvest during that interval. Used this coefficient to account implicitly for growth, defect, etc. in estimating net accumulation (see next section).
Valuation: Followed Vincent (1997) and Vincent, Rozali, and Associates (1997) in calculating net accumulation of roundwood by applying a generalized version of El Serafy’s method, which relaxed the assumption of an infinitely large marginal cost elasticity. Assumed the elasticity equaled 1. Estimated the number of years until exhaustion by dividing roundwood stock by the product of harvest and the timber depletion coefficient. Used a 10-percent discount rate.
Official status: Study conducted for the Asian Development Bank.
Additional comments: Covered 14 countries in Asia. One of the few studies to apply the generalized El Serafy method. Concluded that net accumulation was greater for soils than for roundwood or subsoil assets in most countries, and that net accumulation summed across all resources was small relative to gross domestic savings. The ratio of net accumulation to total resource rent rose sharply during the period, however.
Australia (I)
Reference: Young (1993).
Period: 1980-89.
Scope: Subsoil assets, soil erosion, and salinization, in addition to forest resources.
Forest resources: Natural habitat.
Links to national accounts: (i) Current accounts—Added net accumulation of habitat, due to conversion of native forests, to GDP. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Estimated annual rate of conversion of native forests at 230,000 hectares per year.
Valuation: Multiplied annual area of converted native forests times $1,000 per hectare, their assumed asset value as natural habitat.
Official status: Academic study.
Additional comments: Concluded that net accumulation of habitat was equivalent to about 0.1 percent of GDP, was much smaller than net accumulation of subsoil assets (by a factor of about 1,000), and was also smaller than agricultural land degradation, though not by nearly as much.
Australia (II)
Reference: Skinner (1995), Joisce (1996).
Period: 1989-92.
Scope: Subsoil assets, land, and livestock, in addition to forests.
Forest resources: Timber in native forests (including broadleaved plantations) and coniferous plantations.
Links to national accounts: (i) Current accounts—Made no adjustments. (ii) Asset accounts—Calculated asset value of forests for timber production and linked it to asset accounts. Treated native forests as non-cultivated, tangible, non-produced, non-financial assets, and plantations as inventories of produced, non-financial assets.
Physical accounts: Classified forest areas and associated growing stocks by state, ownership (public/private), legal availability for timber production, type (species), management system (even-aged/uneven-aged), and age class.
Valuation: For mature native forests, set asset value equal to total stumpage value: multiplied standing commercial volume times applicable official stumpage fees. For immature native forests, set asset value equal to projected harvest volume, times applicable stumpage fees (current levels), discounted by the number of years until maturity. Used a range of discount rates (5, 7.5, and 10 percent), though Skinner (1995) showed value estimates for just one (7.5 percent). Ignored value of thinnings. For coniferous plantations, used insured values, which were regarded as providing good estimates of market values.
Official status: Pilot project conducted by Australian Bureau of Statistics, to investigate implementation of SNA93 recommendations.
Additional comments: Provides probably the most sound estimates of asset values of timber stocks. Incorporated uneven-aged forests as well as even-aged forests, by using data on tree diameters to estimate years until harvest in the former case. Intend to estimate stumpage values, rather than using stumpage fees as a proxy, when data become available (expected "very shortly"). Found that native forests accounted for 1.3 percent of the value of non-produced, non-financial assets in 1992, while coniferous plantations accounted for 0.5 percent of produced, non-financial assets. In absolute terms, the value of native forests was about a third higher than the value of plantations.
Austria
Reference: Sekot, Gerhold, and Knieling (1996).
Period: Early 1990s (?).
Scope: Forest resources only.
Forest resources: Timber in high forests.
Links to national accounts: (i) Current accounts—Made no adjustments. (ii) Asset accounts—Calculated asset value of forests for timber production, with the eventual intention of linking it to asset accounts.
Physical accounts: Drew data from Austria’s national forest inventory, which (with some additional work) provided information on growing stock by age class and species group.
Valuation: For mature forests, set asset value equal to total stumpage value: multiplied standing timber volume times stumpage value (average log price for species group minus country-wide average logging cost). For immature forests, multiplied area times per-hectare total stumpage value of mature forests times an "age constant," an implicit discount factor based on age class and rotation length.
Official status: Study sponsored by Austrian Central Statistical Office, to investigate implementation of ESA95.
Additional comments: Only study to use the "age constant" approach.
Canada (I)
Reference: Anielski (1992a, 1992b, 1994, 1996).
Period: 1979-91.
Scope: Forest resources only, for just the province of Alberta.
Forest resources: Timber and carbon sequestration in natural forests and plantations.
Links to national accounts: (i) Current accounts—Anielski (1992) added net accumulation of timber to provincial value added in forestry (1979-90). Anielski (1994) did this too and also added net accumulation to provincial GDP (1979-91). Made no adjustment for carbon sequestration, though calculated value. (ii) Asset accounts—Calculated asset value of forest for timber production, but did not link it to asset accounts.
Physical accounts: For growing stock, modeled after Repetto et al. (1989; see Indonesia), with additional detail on forest areas. Additions to growing stock included growth, with mature and immature stocks distinguished, and reforestation (treated as immature stock). Subtractions included harvest, fire, insect infestations, energy development, and agricultural land-use conversion. For carbon, Anielski (1992a) estimated gross annual carbon sequestration by multiplying forest area times annual wood increment (cubic meters per hectare) times a factor converting wood volume to tons of carbon.
Valuation: (i) Calculated net accumulation of timber by net price method: multiplied net depletion (defined as including only mature timber in commercial forests) times average stumpage value. For carbon, calculated value by multiplying quantity sequestered times estimated carbon values (taken from previous studies) ranging from $20/ton to $300/ton. (ii) Set asset value for timber equal to total stumpage value: multiplied volume of mature timber in commercial forests times average stumpage value.
Official status: Study conducted as part of a joint initiative by Statistics Canada and the provincial governments of Alberta and Ontario, to develop pilot renewable and nonrenewable resource accounts for Canada (see Canada (II), below). Author is an official in the Alberta Treasury.
Additional comments: Anielski (1992b) presented the first timber account in Canada, and Anielski (1992a) presented one of the first forest accounts to include carbon values. According to Anielski (1994), net accumulation of timber ranged from -27.2 percent to 34.3 percent of provincial forestry value added, but only -0.29 percent to 0.50 percent of provincial GDP.
Canada (II)
Reference: Statistics Canada (1997), Baumgarten (1996).
Period: 1961-91.
Scope: Forest resources only, for just the province of Ontario.
Forest resources: Timber in natural forests and plantations.
Links to national accounts: According to reports cited above, eventually intend to implement recommendations in SNA93, in particular to include timber in asset accounts. Had not done so at the time of those reports.
Physical accounts: Based on Canada’s Forest Inventory 1991, with values for earlier years constructed using an internally consistent model that simulated the impacts of growth, harvest, natural losses, and other factors. Contained information on both forest areas and growing stocks, for three forest types and 180 single-year age-classes. Categories in the area accounts included: productive and unproductive forests for commercial timber production; reserved (protected), nonreserved but inaccessible, and nonreserved and accessible forests; stocked and nonstocked forests; age class; and hardwood, softwood, or mixed wood. Timber accounts showed opening and closing stocks, growth, and four causes of depletion: harvest, fire, mortality, and roads.
Valuation: Used both the present value method and the net price method to calculate asset value of timber. For the present value method, first calculated the total annual stumpage value of timber harvested and utilized in the province, by subtracting the costs of felling, transporting, and processing timber from the annual production value of forest products industries. In estimating costs, set the return on capital equal to the borrowing rate on corporate bonds. Second, subtracted total annual forest management expenditures (capital expenditures as well as current expenditures) incurred by the government from total stumpage value. Third, used a 5-year moving average to smooth the resulting estimates of net total stumpage values. Fourth, divided the smoothed estimates by 2 percent and 4 percent to calculate asset values. For the net price method, first divided the smoothed estimates from the present value method by annual timber harvest to calculate average net stumpage value per cubic meter. Then, multiplied average net stumpage value times standing timber volume.
Official status: Pilot project conducted by Statistics Canada.
Additional comments: Presented the longest time series of any study, and had access to some of the best data. One of the few studies to compare the asset value and net price methods and to use smoothed values. Found that the latter generated larger estimates, though only slightly larger toward the end of the period than those from the capitalized-value method for a 2-percent discount rate. According to all methods, the value of Ontario’s timber stocks was larger in 1991 than in 1961.
Chile
Reference: Claude and Pizarro (n.d.).
Period: 1985-93 (plantations), 1985-94 (native forests).
Scope: Subsoil assets and fisheries, in addition to forest resources.
Forest resources: Timber in native forests and plantations (pine and eucalyptus).
Links to national accounts: According to report cited above, eventually intend to add estimates of net accumulation to NDP. Had not done so at the time of that report.
Physical accounts: Pertained to forest areas, not growing stocks. Classified native forests into protected and unprotected areas, site quality (for unprotected forests only), causes of deforestation (fire, agriculture, timber plantations), and managed logging vs. unmanaged logging ("creaming"). Prepared similar accounts for plantations, recording source of land for new plantations (native forests vs. other land).
Valuation: Not completed at the time the report was written. The report did not describe the methods to be employed.
Official status: Study initiated by National Accounts Department of the Central Bank of Chile, to investigate implementation of SNA93 and SEEA recommendations.
Additional comments: The physical accounts for native forests attracted world-wide attention when preliminary results were leaked to the press, as they indicated a sharp decrease in remaining area. The Central Bank has reportedly terminated the project.
Costa Rica (I)
Reference: Repetto et al. (1991).
Period: 1970-89.
Scope: Agricultural soils and fisheries, in addition to forest resources.
Forest resources: Timber in natural forests. Focused on two processes: deforestation of old-growth forests and reestablishment of second-growth forests. Second-growth forests referred to forests that had naturally reestablished themselves in abandoned pastures and farms, not to residual forests left by logging.
Links to national accounts: (i) Current accounts—Added net accumulation of timber to NDP, net domestic investment, and value added in agriculture. (ii) Asset accounts—Calculated asset value of second-growth forests for timber production, but did not link it to asset accounts.
Physical accounts: Used a geographic information system (GIS) to construct estimates of forest areas over time, and ecological relationships to construct estimates of growing stocks in those areas. Regarding areas, began by using spatial data on ecological life zones, soil groups, slope, and geology to define land units. Then overlay land-use maps for 1960 and 1984 on the land units to identify forested areas. Interpolated and extrapolated those areas to other years, using supplemental data from agricultural censuses conducted in 1963 and 1973. Regarding growing stocks, used ecological relationships (based on data from permanent plots) to estimate potential standing biomass and potential biomass growth rates in all trees with DBH ≥ 10 cm. Converted those estimates to expected values net of defect and biomass in tree parts other than the bole and main br anches.
Valuation: Calculated net accumulation by the present value method. For deforestation, set net accumulation equal to the sum of two components: loss of standing timber value and loss of future harvest value. Set the former equal to total stumpage value (average stumpage value times net commercial standing timber volume), and the latter equal to the asset value of total stumpage values from an infinite series of future timber harvests. For reestablishment of second-growth forests, estimated the asset value of total stumpage value from future timber harvests, and then set net accumulation equal to the difference between these values from one year to the next. For both deforestation and reestablishment of second-growth forests, excluded forests in inaccessible areas or on slopes too steep for logging, and excluded timber volumes in trees below 50 cm dbh or in noncommercial species. Calculated site-specific stumpage values by adjusting for composition of standing volume by density class and by varying hauling costs according to distance from mill.
Official status: Study conducted by the World Resources Institute and the Tropical Science Center in Costa Rica at the invitation of the Costa Rican Minister of Natural Resources, Energy, and Mines.
Additional comments: After the World Resources Institute study in Indonesia, the second-most widely cited study on natural resource depletion and national income accounts. Pioneered the use of a GIS and asset values for estimating net accumulation of natural resources. Found that net accumulation of forests was substantially larger than net accumulation of soils and fisheries, due primarily to the loss of standing timber value due to deforestation. Net accumulation of second-growth forests was positive in most years, indicating an increase in asset value. Net accumulation of forests was equivalent to approximately 4 percent of GDP and 20 percent of gross domestic investment.
China
Reference: Li (1993).
Period: 1980-88.
Scope: Forest resources only.
Forest resources: Timber.
Links to national accounts: (i) Current accounts—Added value of growth of timber to GDP, and added net accumulation of timber to NDP. (ii) Asset accounts—Calculated asset value of forests for timber production, but did not link it to asset accounts.
Physical accounts: Based on physical accounts in Repetto et al. (1989; see Indonesia). Included six categories of subtractions from timber stocks: harvest, "construction in forest area," "consumption in culture operation," "consumption of energy" (fuelwood?), "calamities and other losses," and "other consumption."
Valuation: (i) Valued timber growth by multiplying annual volume of growth times accumulated forest management costs expressed on a unit basis. Accumulated costs with interest, from the year of forest regeneration up to the current age. Calculated net accumulation by a variant on the net price method: multiplied net depletion times the unit accumulated cost. (ii) Calculated asset value of timber by multiplying timber stock at beginning or end of year times unit accumulated cost. Did not separate out a capital gains ("revaluation") entry.
Official status: Study sponsored by the World Resources Institute and the Ford Foundation, and conducted by Chinese experts from numerous government agencies.
Additional comments: Kong et al. (1994) describe subsequent work, which included case studies on how to value particular forest functions. They did not calculate the values at the national level.
Costa Rica (II)
Reference: Aguirre (1996).
Period: 1993.
Scope: Forest resources only.
Forest resources: Timber in natural forests and plantations, carbon sequestration, watershed protection, ecotourism.
Links to national accounts: (i) Current accounts—Added net accumulation of timber, carbon stocks (a function of timber volume), and watershed and ecotourism services (a function of forest area) to net value added in forestry. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: For growing stock, similar to those in Repetto et al. (1989; see Indonesia). Defined stock as standing volume in commercial timber trees with DBH ≥ 10 cm. Included two additions to stocks (growth, reforestation) and five subtractions (harvest, logging damage, deforestation, fire damage, and stand mortality). Assumed net amount of carbon sequestered was proportional to net depletion of timber stock. For watershed and ecotourism services, constructed accounts showing forest areas.
Valuation: Calculated net accumulation by the net price method and variants thereof. For timber, multiplied net depletion times average stumpage value. For carbon, converted net depletion of timber from cubic meters to tons of carbon, and then multiplied by US$10 per ton of CO2. For watershed services, multiplied change in forest area times 9000 cubic meters per hectare per year times average water rate paid by Costa Rican water consumers. For ecotourism, multiplied change in forest area times US$74.04 per hectare, the estimated net expenditure by international ecotourists.
Official status: Academic study, to investigate how SEEA can be adapted to Costa Rican forest resources.
Additional comments: Concluded that actual net value added in forestry was only 4.3 percent of the official value. Net accumulation of timber accounted for most of the discrepancy (more than half), followed by net accumulation of watershed services.
Ecuador
Reference: Kellenberg (1995).
Period: 1971-90.
Scope: Subsoil assets (petroleum), in addition to forest resources.
Forest resources: Timber in natural forests and plantations.
Links to national accounts: (i) Current accounts—Added net accumulation of timber to NDP and net domestic investment. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Reportedly similar to accounts constructed for Indonesia by Repetto et al. (1989; see Indonesia), although this is not entirely evident from the report cited above.
Valuation: Calculated net accumulation by variations on the two methods in Sadoff (1993; see Thailand), i.e. the net price method (called the "depreciation method") and the replacement cost method (called the "user cost method"). For the former, multiplied an adjusted measure of net depletion of timber stocks times average stumpage value. Adjusted net depletion downward to include only the potential "volume actually commercialized." Differentiated stumpage values according to 9 timber-producing regions and 3 potential export sites. For the second method, estimated the replacement cost of timber plantations required to offset the value of the net depletion of natural timber stocks. Did this in three steps. First, divided the net accumulation estimate from the net price method by the net present value of one hectare of a representative timber plantation, to estimate the number of hectares of new plantations required to offset the reduction in timber value of the natural forest. Then, reduced this number by the actual area of new plantations. Finally, multiplied the resulting amount times the capitalized cost of establishing and maintaining one hectare of a representative plantation.
Official status: Academic study (Ph.D. dissertation).
Additional comments: One of two studies to compare net accumulation estimates from the net price and replacement cost methods. Found that the two methods yielded estimates differing by about a third, with estimates of the net price method being larger. Net accumulation of timber was much smaller than net accumulation of petroleum and was equivalent to about 0.6 percent of GDP and about 5 percent of depreciation of human-made capital.
Finland (I)
Reference: Koltolla and Mukkonen (1996).
Period: 1990-94.
Scope: Forest resources only.
Forest resources: Timber in natural forests and plantations.
Links to national accounts: (i) Current accounts—Added value of net growth of timber to GDP and value added in forestry and logging. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Similar to Repetto et al. (1989; see Indonesia), with more detail on species composition. Included estimates of opening and closing stocks, annual growth, and "total drain," comprised of net removals (sawlogs, pulpwood, fuelwood), silvicultural waste, and natural losses. Presented this information for three forest types: pine, spruce, broadleaved.
Valuation: Multiplied net growth (growth minus total drain) in each forest type times corresponding average stumpage value.
Official status: Study conducted by Statistics Finland, to investigate implementation of recommendations for forest resources in SNA93 and ESA95 (European System of Accounts). Did not consider recommendations in SEEA.
Additional comments: Critiqued the SNA93/ESA95 recommendation that net growth in cultivated forests be treated as "work-in-progress," arguing that it is "in contradiction with the aim of avoiding imputed concepts of income in national accounts" (p. 185) and that it creates an inconsistency with the treatment of net growth in "controlled but uncultivated" forests and non-controlled forests, which may differ little from cultivated forests. Concluded that the adjustment (for all forests, not just cultivated ones) would be equivalent to only 0.3-0.6 percent of GDP as currently calculated, but up to 30 percent of value added in forestry and logging.
Finland (II)
Reference: Hoffrén (1996).
Period: 1990-95.
Scope: Forest resources only.
Forest resources: Timber; Christmas trees and game; berries, mushrooms, reindeer farming, and lichen; peat; carbon sequestration, biodiversity protection, and recreation; acid deposition and defoliation.
Links to national accounts: Similar to Hulkrantz (1992; see Sweden (I)), but did not distinguish between values of stocks and flows. (i) Current accounts—Made several adjustments to value added in forestry: subtracted depreciation of silvicultural investments and added net accumulation of timber; reallocated the value of production of berries, mushrooms, reindeer farming, and lichen from agriculture; reallocated the production of peat from mining and quarrying; added the nonmarket value of carbon sequestration, biodiversity protection, and recreation; and subtracted damage to timber production caused by acid deposition and defoliation. Made no adjustment for game and Christmas trees, which were already included in forestry value added. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Apparently drew information on growing stocks from existing physical balance sheets for timber resources maintained by Statistics Finland. Structure of accounts for other forest resources varied considerably.
Valuation: Used various methods. Did not need to estimate values for game, Christmas trees, berries, mushrooms, reindeer farming, lichen, peat, and depreciation of investments in timber cultivation, as used existing values in the national accounts. Calculated net accumulation of timber by the net price method: multiplied net depletion (harvest minus growth) times average stumpage value. For carbon, converted net depletion of timber volume to net change in tons of sequestered carbon, and multiplied the latter times the Finnish carbon tax. For biodiversity, calculated cost of complying with forestry regulations intended to protect biodiversity (e.g., forgone stumpage value associated with more selective harvesting). For recreation, multiplied number of visitors times value estimates for a visitor-day from willingness-to-pay studies. For acid deposition, multiplied tons of nitrogen oxides and sulfur dioxide deposited in forests times unit abatement costs to polluting industries. For defoliation, multiplied estimated forgone timber growth times average stumpage value.
Official status: Study initiated by Statistics Finland, to investigate implementation of SEEA recommendations. Objective is to integrate forest resource accounts and Finland’s national accounts.
Additional comments: Most ambitious study in terms of addressing nontimber values. Found that gross and net values associated with timber production differed little, and that the net value of timber production accounted for two-thirds of total net value in forestry. Recreation and carbon sequestration provided next largest values.
Indonesia
Reference: Repetto et al. (1989).
Period: 1970-84.
Scope: Subsoil assets (petroleum) and agricultural soils, in addition to forest resources.
Forest resources: Timber in natural forests and plantations.
Links to national accounts: (i) Current accounts—Added net accumulation of timber to GDP and gross domestic investment. (ii) Asset accounts—Calculated asset value of forests for timber production, but did not link it to asset accounts.
Physical accounts: Pertained to growing stock, not area, although data on area underlay some of the volume estimates (e.g., for additions to timber stocks due to plantation establishment, and subtractions due to deforestation). Applied the annual accounting identity,
Closing stock = Opening stock + Additions - Subtractions.
Additions included growth and reforestation; subtractions included harvest, logging damage, fire damage, and losses due to deforestation. Defined growing stock as gross wood volume in the boles of all living trees with DBH ≥ 10 cm. For growth in natural forests, assumed constant area of logged-over forests, growing at 1.5 m3/ha/yr (net commercial volume). Assumed harvests occurred only in old-growth forests. For deforestation and fire damage, multiplied area estimates times estimates of gross standing volumes for all trees with DBH ≥ 10 cm.
Valuation: (i) Calculated net investment (value of the change) for timber by a variation on the net price method. For natural forests, multiplied net depletion of timber stock (subtractions minus additions) times average stumpage value (average price minus average logging cost). But valued additions due to growth, and subtractions due to logging damage, fire damage, and deforestation, at half the average stumpage value, as a proxy for the average asset value of eventual harvests in logged-over forests. Set net accumulation of plantations equal to zero, because they generated only an ordinary rate of return on invested capital. (ii) Calculated asset value of timber by multiplying timber stock at beginning or end of year times corresponding average stumpage value. Separated out a capital gains ("revaluation") entry, defined as the difference between change in value of the stock and net investment.
Official status: Study conducted by the World Resources Institute, independent of the Indonesian government. The "Acknowledgments" section of the report notes interest by the Minister of Environment and Population.
Additional comments: The most widely cited study on natural resource depletion and national income accounts. Popularized the net price approach for estimating net investment and valuing the timber stock. Found that net investment in timber was substantially smaller than for petroleum and substantially larger than for agricultural soils, and was equivalent to approximately 5 percent of GDP and 25 percent of gross domestic investment.
Malaysia (I)
Reference: Vincent et al. (1993).
Period: 1971-89.
Scope: Subsoil assets and agricultural soils, in addition to forest resources.
Forest resources: Timber, carbon sequestration, biodiversity, and game in natural forests.
Links to national accounts: (i) Current accounts—Added net accumulation of timber to NDP and net domestic investment. Calculated net accumulation of carbon and biodiversity stocks, and value of nonmarket production of game, but did not link them to the national accounts. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: For timber, similar to the physical accounts in Repetto et al. (1989; see Indonesia), with more explicit attention paid to forest areas and the distinction between old-growth and second-growth forests. Constructed accounts to be internally consistent in terms of transfers of areas from old-growth to second-growth forests due to logging, and accounted for harvesting and deforestation in both old-growth and second-growth forests. Defined growing stock as including only trees of commercial size. Created separate regional accounts for Peninsular Malaysia, Sabah, and Sarawak. For carbon, converted timber volumes to tons of carbon equivalents. For biodiversity, used forest areas to calculate a habitat index (based on island biogeography theory), which predicted percentage of original species that had been driven to local extinction. For game, assumed game harvest was proportional to forest area.
Valuation: Calculated net accumulation of timber by net price method: multiplied net depletion of timber (subtractions from timber stock minus additions) times smoothed value of average stumpage value (smoothed by using fitted values from regression on time trend). Calculated net accumulation of carbon by converting net depletion of timber from cubic meters to tons of carbon, and then multiplying by range of estimates of carbon taxes for U.S. Calculated net accumulation of biodiversity by multiplying number of new extinctions times unit value of a species. Used various methods to estimate the latter: expenditure to relocate a locally endangered species (the Asian elephant) to protected areas, expenditure to reintroduce a locally extinct species (the milky stork), and net present value of genetic improvements due to wild genes from a local fruit tree (durian). Calculated value of nonmarket production of game by multiplying hectares of forest in Sarawak times $10.28 per hectare, the assumed value of annual game production (based on reported values in the literature).
Official status: Study sponsored by the Economic Planning Unit in the Prime Minister’s Department, as part of the Malaysian National Conservation Strategy.
Additional comments: One of the first studies to include a range of nontimber benefits as well as timber, although it did not link the former to the national accounts. Concluded th at net accumulation of timber exceeded net accumulation of subsoil assets.
Malaysia (II)
Reference: Vincent (1997), Vincent et al. (1997).
Period: 1970-90.
Scope: Subsoil assets, in addition to forest resources.
Forest resources: Timber in natural forests.
Links to national accounts: (i) Current accounts—Added net accumulation of timber from NDP and net domestic investment at both the national and subnational (Peninsular Malaysia, Sabah, Sarawak) levels. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Same as in Vincent et al. (1993; see Malaysia(I)).
Valuation: Calculated net accumulation of timber by applying a generalized version of El Serafy’s (1989) formula, which relaxed the assumption of an infinitely large marginal cost elasticity. Applied the formula to just timber depletion in old-growth forests, on the assumption that second-growth forests would be managed for sustained-yield timber production. Excluded defect and logging damage from calculation of net depletion. Used a marginal cost elasticity of 3 and a 10-percent discount rate.
Official status: Academic study, conducted in collaboration with Institute of Strategic and International Studies Malaysia. Updated and revised Vincent et al. (1993), which was sponsored by the Malaysian government.
Additional comments: One of the few studies to modify subnational accounts, to exclude defect and logging damage from the calculation of net depletion, and to apply the generalized version of El Serafy’s formula. Unlike Vincent et al. (1993), concluded that net accumulation of subsoil assets exceeded net accumulation of timber toward the end of the period. Concluded that net accumulation of timber was very large relative to NDP and net domestic investment in Sabah and Sarawak, but not at the national level.
México
Reference: van Tongeren et al. (1993).
Period: 1985
Scope: Subsoil assets (petroleum) and environmental degradation (air and water pollution, solid waste, soil erosion, and groundwater depletion), in addition to forest resources.
Forest resources: Timber, apparently in both natural forests and plantations, and soil erosion in forestland.
Links to national accounts: (i) Current accounts—Added net accumulation of timber, forestland, forest soils, and developed land (land used in agriculture, pasturing, and urban areas) to NDP and value added in pertinent industries (e.g., ones using converted forestland as an input). (ii) Asset accounts—Did not calculate asset value of forests, as viewed them as "nonproduced environmental assets."
Physical accounts: Details not clear. Drew data on forest resources (area and growing stock, without detail on species composition) from the national forest inventory, data on changes in land use from an inventory prepared by the Secretaria de Agricultura and Recursos Hidraulicos, and data on soil erosion in different land uses from a report prepared by the Comision Nacional de Ecologia.
Valuation: Calculated net accumulation of timber by both the net price method (multiplied net change in timber stock times the national average stumpage value) and El Serafy’s method. Calculated net accumulation of forestland and developed land by the present value method. Estimated that asset values equaled 38.15 million pesos/ha for forestland (timber production only), 2.64 million pesos/ha for agriculture, 1.99 million pesos/ha for pastureland, 75.50 million pesos/ha for urban land, and zero for abandoned shifting cultivation. Calculated net accumulation of forest soils by the replacement cost method: estimated cost of fertilizer required to offset productivity decline caused by erosion.
Official status: Study conducted by the U.N. Statistical Division, the World Bank, and the Mexican Instituto Nacional de Estadistica, Geografia, e Informatica (INEGI), with partial funding from UNDP. Intended to test and illustrate key features of the SEEA. INEGI is the government agency responsible for compiling the Mexican system of national accounts.
Additional comments: The only study to compare net accumulation estimates from the net price and El Serafy methods, and one of the few to treat deforestation as a process that not only reduced the stock of forestland but increased the stock of developed land. Found that the net price method yielded much higher (factor of 15) estimates of net accumulation of timber, and that deforestation decreased the total value of land. Net accumulation of timber was equivalent to 2.3 percent of NDP, net accumulation of forestland 52 percent, and net accumulation of forest soils 0.2 percent. All these values were much lower than values associated with petroleum depletion.
Nepal
Reference: Katila (1995).
Period: 1991.
Scope: Forest resources only.
Forest resources: Timber, fuelwood, fodder.
Links to national accounts: (i) Current accounts—Added the value of nonmarket production of timber, fuelwood, and fodder to GDP, and the net accumulation of timber and fuelwood to GDP thus modified and to modified value added in forestry. Did not calculate net accumulation of fodder, citing rising stocks. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Assumed nonmarket production of timber, fuelwood, and fodder equaled consumption, with a 5-percent adjustment to account for logs smuggled to India. Constructed consumption estimates using data from various sources. For timber and fuelwood, set net depletion equal to the difference between estimated production and "sustainable supplies" as reported in the Master Plan for the Forestry Sector of Nepal. Did not calculate net depletion of fodder.
Valuation: a. For adjustments to GDP for nonmarket production, used different methods for the three nonmarket goods. For timber, multiplied production times proxy for national average stumpage value (log price of one species, sissoo, minus manual harvesting costs and risk margin). For fuelwood, multiplied production times shadow price estimated by three methods: opportunity cost of time spent collecting fuelwood (weighted average of shadow wage rate during slack season and market wage during peak season), price of fuelwood sold in local markets, and price of a substitute fuel (cattle dung). Preferred the first method, which yielded median estimate. For fodder, multiplied production times shadow price estimated by two methods: opportunity cost of time spent collecting fodder, and the implicit value of fodder as an input in producing milk (roughly speaking, the input-output coefficient times milk price). Preferred the latter method, which yielded slightly lower estimate (conservative approach).
b. For net accumulation, intended to multiply net depletion times net price, and add the "revaluation" term as defined by Repetto et al. (1989; see Indonesia). Due to lack of data on price changes, did not calculate "revaluation" term. For timber, set net price equal to proxy for stumpage value described above. For fuelwood, used shadow price described above instead of net price.
Official status: Academic study.
Additional comments: Report cited above presents main findings of a study funded by the Finnish International Development Agency, Modified GDP Accounts for Nepal: Case Study of Accounting for Market and Non-Market Production of Timber, Fuelwood, and Fodder (1993). We were unable to obtain the full report of the study. One of the few studies to adjust GDP for production of nonmarket forest-related goods; in some ways, modeled after Peskin (1989; see Tanzania). Found that the addition of the three nonmarket goods increased forestry’s GDP share from 4.9 percent to 14.6 percent, with timber being responsible for more than half of the increase. Net accumulation was equivalent to 18 percent of modified value added in forestry.
New Zealand
Reference: Bigsby (1995).
Period: 1978-present.
Scope: Forest resources only.
Forest resources: Timber in plantations. Clough (1992) proposed a framework for natural forests but did not implement it.
Links to national accounts: (i) Current accounts—The New Zealand System of National Accounts (NZSNA) treats growth of plantations as "work in progress" (change in inventories) and adds the associated value to GDP. (ii) Asset accounts—NZSNA records changes in value of plantations in asset accounts.
Physical accounts: NZSNA obtains growing stock estimates for plantations from annual updates of the National Exotic Forest Description (NEFD).
Valuation: NZSNA multiplies aggregate standing timber volume times national average stumpage value for plantation species.
Official status: NZSNA is implementing the procedures summarized above.
Additional comments: Changes in value of plantations accounted for about 1.5 percent of GDP during 1989-93. Bigsby (1995) argued that asset values would provide more accurate estimates of plantation values, and that the NEFD contains sufficient data to calculate them (e.g., regionalized data on areas planted by species, age, silvicultural treatment, and yield tables).
Papua New Guinea
References: Bartelmus et al. (1992, 1993), Bartelmus (1994).
Period: 1986-90.
Scope: Subsoil assets and energy, in addition to forest resources.
Forest resources: Nontimber values ("ecological, social, and spiritual values") in natural forests.
Links to national accounts: (i) Current accounts—Subtracted value of nontimber values lost due to deforestation and logging from NDP and from net value added in agriculture. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Divided forests into two categories: potential economic use (forests where logging is financially viable) and environmental use (forests where logging is not viable, due to inaccessibility or low timber quality). Assumed that the area of each remained constant over time. Subdivided the first category into virgin and logged-over forests, and the second into shifting agriculture, shrubs, forest plantations, and natural forest. Estimated changes in areas in these subcategories over time.
Valuation: Calculated net loss of nontimber values due to logging and deforestation by multiplying areas logged and converted to shifting cultivation, respectively, by per-hectare values. After considering several possible valuation approaches (restoration costs, avoidance costs, defensive expenditures), decided to use compensation awards as an indicator of per-hectare values, as tribal groupings and clans, who own land and water resources in Papua New Guinea, are legally entitled to receive compensation when forests are degraded. For deforestation, used 7 kina/m3, converted to a hectare basis, which is the amount of compensation paid by logging companies to landowners. For logging, added 2 kina/m3 (the "forest management levy") to this compensation rate. The authors noted that conventional national accounts should already reflect these payments, but only if the payments are actually made, which is not always the case.
Official status: Study sponsored by the U.N. Statistical Office and the World Bank to test and illustrate key features of the SEEA. The study team consulted with, among others, the National Statistical Office, Department of Finance and Planning, and the Office of the Prime Minister in Papua New Guinea.
Additional comments: Found that value of forest degradation was smaller in most years than the value of environmental degradation associated with mining, and was equivalent to 0.7-6.7 percent of NDP and 7.6-57.3 percent of value added in agriculture. The authors originally intended to estimate net accumulation of timber, but they were unable to translate their estimates of changes in forest areas into estimates of changes in timber stocks. They commented that the large variety of forest types prevented them from simply multiplying areas times a simple conversion factor (cubic meters of timber per hectare of forest), that reported timber harvests were probably understated, and that reliable data were not available on forest regeneration. They suggested that if they had been able to estimate net depletion of the timber stock, they would have calculated net accumulation by an approach similar to the one in Repetto et al. (1989); (see Indonesia).
Philippines (I)
References: IRG et al. (1991, 1992).
Period: 1970-89.
Scope: Forest resources only. Phase II of the project planned to cover additional resources.
Forest resources: Roundwood (timber, fuelwood, charcoal) in natural forests (dipterocarp forests, pine forests, mangroves) and plantations; rattan.
Links to national accounts: (i) Current accounts—Added net accumulation of roundwood and rattan to NNP. (ii) Asset accounts—Calculated asset value of dipterocarp forests for timber production, but did not link it to asset accounts.
Physical accounts: Essentially identical to the physical accounts in Repetto et al. (1989; see Indonesia), with more explicit attention paid to the distinction between old-growth and second-growth forests.
Valuation: (i) Calculated net accumulation by both the net price method and the present value method. For the former, set net accumulation equal to not just the product of net depletion of roundwood or rattan stocks and the corresponding average stumpage value (as in Repetto et al. 1989; see Indonesia), but to the sum of that product and the "revaluation" term as defined by Repetto et al. (1989). For the second method, calculated the asset value of dipterocarp forest by assuming a 15-percent discount rate, a 20-year time horizon for liquidating timber stocks in old-growth forests (i.e., 1990 = depletion date), and sustained-yield timber production from second-growth forests under a 40-year cutting cycle. Set net accumulation equal to the difference between successive annual values. (ii) Calculated asset value of dipterocarp forest by procedure described above.
Official status: Study conducted by International Resources Group, Ltd., in association with Mandala Agricultural Development Corporation and Edgevale Associates, for the Philippines Department of Environment and Natural Resources (DENR), with technical support from the DENR and the National Statistical Coordination Board.
Additional comments: Apparently the first study to compare alternative methods for estimating net accumulation of timber. Found that the net price and present value methods yielded very different estimates, with the net price method yielding estimates approximately 30 times larger than those from the present value method. Concluded that the latter method was the more sound. Estimates of net accumulation from that method were equivalent to only 0.2 percent of NNP. Net accumulation of plantations, pine forests, mangroves, and rattan resources was tiny compared to net accumulation of dipterocarp forests.
Philippines (II)
Reference: Cruz and Repetto (1992).
Period: 1970-87.
Scope: Agricultural soils and fisheries, in addition to forest resources.
Forest resources: Timber in natural forests.
Links to national accounts: (i) Current accounts—Added net accumulation of timber to GDP and to gross investment in agriculture, which includes forestry and fisheries. (ii) Asset accounts—Calculated asset value of forests for timber production, but did not link it to asset accounts.
Physical accounts: Essentially identical to the physical accounts in Repetto et al. (1989; see Indonesia).
Valuation: Essentially identical to valuation in Repetto et al. (1989; see Indonesia).
Official status: Study conducted by the World Resources Institute, independent of the Philippines government. The "Acknowledgments" section of the report notes "encouragement" provided by several government officials, for example for Director-General of the National Economic and Development Authority and the Secretary of the Department of Environment and Natural Resources.
Additional comments: The third in a series of studies by the World Resources Institute (see Costa Rica (I) and Indonesia). Unlike the other two, placed the net accumulation of natural resources in the context of structural adjustment programs. Found that net accumulation of timber was substantially larger than for agricultural soils and fisheries, was equivalent to approximately 3 percent of GDP, and was larger than gross investment in agriculture in most years.
Sweden(I)
Reference: Hulkrantz (1992).
Period: 1987.
Scope: Forest resources only.
Forest resources: Timber; fuelwood, berries, mushrooms, and game; reindeer forage; carbon sequestration; biological diversity; and forest soils.
Links to national accounts: (i) Current accounts—Added the value of nonmarket production of several nontimber benefits (fuelwood, berries, mushrooms, and game), and the net accumulation of timber stocks, reindeer forage, sequestered carbon, biological diversity, and forest soils, to net value added in forestry. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: None.
Valuation: a. Used a variety of methods to value nonmarket production. For fuelwood and berries, scaled official estimates upward using the ratio of estimated actual physical production to official production. For mushrooms and game, used survey estimates of physical production and market prices. b. Also used a variety of methods for net accumulation. For timber, used a variant on the net price method: multiplied net depletion times average stumpage value, and added silvicultural expenditures. For reindeer forage, used the present value method: valued a unit of forage by the price of its substitute, hay, and applied a 5 percent discount rate. For carbon, converted net depletion of timber volume to net change in tons of sequestered carbon, and multiplied the latter times the Swedish carbon tax. For biological diversity, used the opportunity costmethod: stumpage value of forests that needed to be taken out of timber production to increase protected area to 10 percent of total forest area. For forest soils, used the replacement cost method: calculated cost of limestone and magnesium needed to offset acid deposition and maintain stocks of base cations.
Official status: Academic study. Consulted officials in the Central Bureau of Statistics.
Additional comments: One of first studies to address nonm arket values, and still one of the most ambitious (surpassed only by Hoffrén 1996; see Finland). Concluded that net value added in forestry was 34 percent larger than gross value added reported in official income accounts. Discrepancy was due mainly to appreciation of timber stock and sequestration of carbon. Values associated with timber far exceeded nonmarket values: the former accounted for 81 percent of net value added.
Sweden (II)
Reference: Eliasson (1996).
Period: 1987, 1991. Estimates for 1987 are minor revisions of Hulkrantz’s (1992) estimates. See Sweden (I).
Scope: Same as Hulkrantz (1992).
Forest resources: Same as Hulkrantz (1992).
Links to national accounts: Same as Hulkrantz (1992).
Physical accounts: Same as Hulkrantz (1992).
Valuation: Same as Hulkrantz (1992).
Official status: Same as Hulkrantz (1992).
Additional comments: Replication of Hulkrantz (1992) study. Obtained very similar results for both 1987 and 1991.
Tanzania
Reference: Peskin (1989).
Period: 1980.
Scope: Forest resources only.
Forest resources: Fuelwood.
Links to national accounts: (i) Current accounts—Added the value of nonmarket production of fuelwood to GDP and NDP, and the net accumulation of fuelwood to NDP. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: None.
Valuation: a. Adjusted GDP for value of nonmarket fuelwood production by the opportunity costmethod. First, multiplied estimated person-days per year spent by households collecting fuelwood times the opportunity cost of time (assumed to equal the Tanzanian minimum wage). Then, deducted from this amount the value of household fuelwood collection already included in the national accounts. Finally, added the remaining amount to GDP. b. Calculated net accumulation of fuelwood by a method equivalent to the net price method. First, estimated annual volume of regenerated fuelwood. Then, multiplied this volume times the imputed unit value from the calculations in "a." Next, subtracted this product from the total fuelwood value in "a." Finally, subtracted the remaining amount from NDP.
Official status: Example included in World Bank study covering broader issues of natural resources and national income accounts.
Additional comments: First study to correct GDP for exclusion of nontimber values, and one of the first to correct NDP for net accumulation of forest capital. Concluded that actual production value of fuelwood was more than 10 times greater than official value, and this increased estimated GDP by 6.3 percent. Net accumulation was equivalent to 69 percent of forestry value added and 5.5 percent of adjusted NDP.
Thailand
References: Sadoff (1993, 1995).
Period: 1970-90.
Scope: Forest resources only.
Forest resources: Timber in natural forests. Focused on reductions in timber stocks due to deforestation.
Links to national accounts: (i) Current accounts—Added net accumulation of timber to NDP, net domestic investment, and value added in forestry and agriculture. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Estimated areas and associated densities of standing commercial timber volumes (cubic meters per hectare, for trees with a girth ³ 100 cm at breast height) for four forest types (tropical evergreen, mixed deciduous, dry dipterocarp, pine) in four regions (northern, northeastern, central, southern). Related change in density between forest inventories to change in forest area, and used this relationship to predict densities for years other than inventory years. Multiplied area times density to estimate timber stock, and set net depletion equal to change in stock from one year to the next.
Valuation: Calculated net accumulation of timber by both the net price method (referred to as the "depreciation method") and the replacement cost method (referred to as the "user cost method"). For the former, multiplied an adjusted measure of net depletion times stumpage value. Adjusted net depletion downward to exclude noncommercial species and a "normal" amount of timber damaged during logging. For the second method, multiplied net area deforested times the per-hectare cost of reforestation. Set the latter equal to the discounted sum of establishment and maintenance costs over a single plantation rotation.
Official status: Academic study (Ph.D. dissertation).
Additional comments: First study to compare net accumulation estimates from the net price and replacement cost methods. Found that the two methods yielded similar estimates from the mid-1970s forward. According to both, net value added was negative in forestry in most years (net accumulation, which was negative, exceeded value added), but positive in agriculture in all years. Net accumulation of timber was equivalent to about 2 percent of GDP and about 20 percent of the depreciation of human-made capital.
United States
Reference: Howell (1996).
Period: 1987.
Scope: Subsoil assets, land, and air and water quality, in addition to forest resources.
Forest resources: Timber, forestland.
Links to national accounts: (i) Current accounts—Developed framework for linking changes in forest resources to current accounts, but did not implement it. (ii) Asset accounts—Calculated asset values of timber and forestland stocks and included them in asset accounts. Treated both as "Produced assets" ("Developed natural assets"), with timber being a "Cultivated fixed natural growth asset" (not "Work-in-progress") and forestland being in the "Developed land" category. Also included line items for "Timber and other plants of uncultivated forests" and "Undeveloped land" in the "Nonproduced/environmental assets" section of the asset accounts, but did not completely fill in those lines.
Physical accounts: For timber, compiled data on growing stock of live trees of commercial species with DBH ≥ 5 inches on commercial timberland. Apparently, also compiled data on timber harvest and natural growth. For forestland, compiled data on area of all forestland, excluding land in parks, wildlife areas, and other special land uses.
Valuation: Calculated asset value of timber by the net price method. Calculated value of "Opening stocks" by multiplying timber stocks at beginning of year by average stumpage value at the beginning of the year. Calculated value of "Closing stocks" analogously. Set "Depreciation, depletion, degradation" equal to the negative of the product of harvest times average of stumpage values at beginning and end of year. Similarly, set "Capital formation" equal to product of growth times average of stumpage values. Finally, set "Revaluation and other changes" equal to residual amount after subtracting "Opening stocks," "Depreciation, depletion, degradation," and "Capital formation" from "Closing stocks." Calculated asset value of forestland similarly. Calculated value of "Opening stocks" by multiplying forestland area at beginning of year by corresponding average agricultural land price, the assumed opportunity cost of forestry. Calculated value of "Closing stocks" analogously. Set "Depreciation, depletion, degradation" equal to product of net change in forestland area (which turned out to be negative) times average of average agricultural land prices at beginning and end of year. Did not include "Capital formation" entry. Finally, determined "Revaluation and other changes" as a residual.
Official status: Product of the first phase of a three-phase workplan by the U.S. Bureau of Economic Analysis to develop a framework of Integrated Economic and Environmental Satellite Accounts (IEESAs). Presented the proposed framework in April, 1994. According to Howell (1996, p. 181), "At the request of Congress, the work has been put on hold pending completion of a National Academy of Sciences study of the IEESA’s."
Additional comments: One of the few studies to attempt to value timber stocks and forestland separately. Used "smoothed" stumpage values to remove extreme fluctuations reflecting short-run market rigidities. Concluded that asset values of timber and forestland were similar, with the former being slightly larger than the latter, and that both rose during 1987. In both cases, the increases were due overwhelmingly to the "Revaluation and other changes" entry. Both values were a small proportion (less than 3 percent) of "Produced assets."
Zimbabwe
Reference: Crowards (1996).
Period: 1980-89.
Scope: Subsoil assets (gold) and agricultural soils, in addition to forest resources.
Forest resources: Roundwood (fuelwood, construction timber) in natural forests.
Links to national accounts: (i) Current accounts—Added net accumulation of roundwood to GDP and to value added in agriculture, which includes forestry. (ii) Asset accounts—Did not calculate asset value of forests.
Physical accounts: Estimated roundwood consumption in various end uses (fuelwood for rural and urban households and tobacco curing, construction timber for rural households and mining) and additional roundwood lost during land conversion (burning to clear woodlands for agriculture). Set net depletion equal to the difference between the sum of these estimates and the estimated mean annual increment in accessible woodlands.
Valuation: Calculated net accumulation of roundwood by net price method: multiplied net depletion times average stumpage value. Set stumpage value equal to the difference between consumption-weighted roundwood price and opportunity cost of labor used in collecting roundwood (based on the wage rate for female casual agricultural labor).
Official status: Academic study.
Additional comments: One of the few studies conducted in Africa. Found that net accumulation of roundwood accounted for only 0.1-0.3 percent of GDP and was much smaller than net accumulation of subsoil assets and agricultural soils.
