Mitigation Analysis

Carbon Storage in Forestry Projects in Venezuela

Two different forest projects, an industrial plantation (Uverito) and a managed protected area (Ticoporo Reserve), are used here as case studies in order to extrapolate this local experience to a broader context that includes carbon emissions reduction and sequestration. Project selection was based on the following main criteria: a) should be considered successfully or with high implementation potential, b) applicable on larger scale in the country, c) based on sustainable forestry practices, and d) should cover a wide range of possible mitigation options.

The case studies presented here are based on two forest projects that are being implemented in Venezuela for different purposes: an industrial large-scale plantation and a sustainable management project in a forest reserve. We analyze these two ongoing government projects in detail to evaluate their carbon sequestration potential and estimate the associated costs. Our estimates of carbon storage densities based on these two projects are then used to roughly determine the total amount of carbon that might be conserved and sequestered through the implementation of several mitigation options on technically available lands.

The information and data used for developing the case studies were obtained from the Corporacion Venezolana de Guayana (CVG) and the Venezuelan Forest Service (Seforven). The carbon stock accounting method is from Swisher, 1991.

Uverito Plantation

This large plantation project in eastern Venezuela has been under development by a state company (CVG) since 1970. The project was initially designed for pulp and paper production, but due to delay in the construction of the pulp mills, the plantation will also produce sawn wood. By the end of 1993, 400,000 ha of caribbean pine had been planted, with an additional 100,000 ha planned over the subsequent three years (CVG, 1993). The project is located in an area with an average annual temperature of 26¼C and rainfall of 900 mm, classified at the dry end of the dry tropical forest life-zone under the Holdridge system (Holdridge, 1967). The soils are somewhat acidic and sandy, with excess drainage. Thus, potential agricultural productivity is low and the most productive land use is likely to be production forestry.

For the timber plantation project classification, net carbon accumulation is from new accumulated biomass and soil and from harvested biomass that enters long-term storage. The carbon storage density accumulated in plantations by new biomass (CVav) is the long-term average biomass carbon over the period of rotation. CVav depends on CVm, the carbon stored (in tones of carbon/ha) in vegetation planted by the project, upon maturity. The value for CVm depends on the mean annual biomass increment (MABI), the ratio of total-to-stemwood biomass, and the carbon density of wood (Brown et al 1986, Lugo et al 1988). These values that measure growth potential, especially the MABI, vary with species and climate and can be adjusted according to bioclimatic life-zone or land-use capacity (Holdridge, 1967).

The rotation time of the project is 15 years, with a carbon density at maturity (CVm) of 113 tC/ha, based on an annual biomass increment (MABI) of 14.54 cubic meters per hectare per year (m3/ha-yr). This value is based on the goal stated in CVG, 1993, and it is used as the MABI for young forests. The density of wood is 0.52 t/m3, or 0.26 tC/m3, and the stemwood multiplier to convert to total biomass is 1.8.

Assuming the biomass remaining after the harvest is 15% of CVm (about 30% of the biomass before harvest), the average ratio of standing biomass to biomass at maturity (Bav/Bm) for a 15-year rotation is 0.34 and the ratio of standing biomass at harvest to biomass at maturity (Bh/Bm) is 0.5. These values provide an average accumulated biomass carbon (CVav) of 38 tC/ha above that of the reference case (degraded savanna).

Of the biomass harvested at a given time, 50% is useful for timber; based on a mill efficiency of 60% for a well-managed forest industry in Venezuela, 30% becomes timber and the remainder may be used for pulp or fuel. The timber that enters long-term storage is assumed to be used in the tropics and to decay at 2%/yr, making the carbon content of the steady-state value of the harvested biomass (CVh) 34 tC/ha.

For this tropical forest life-zone, the soil carbon storage density in natural forests (CSnat) is 42 tC/ha. Soil carbon accumulation is 15% of CSnat, or 6 tC/ha. The total carbon storage is thus 78 tC/ha. The success rate for this type of project, which is privately managed with considerable investment and participation of local beneficiaries, is assumed to be 80%; this indicates a net carbon storage value of 62 tC/ha.

The total investment cost of the project, including funds for maintenance, administration, training, and research until the plantation begins to yield a positive cash flow, is $1088/ha. This value does not include any opportunity cost for the land on which the project is implemented, because forestry is the highest-value land use available.

These calculations give a net carbon storage of 6.2 MtC for 100,000 ha of new plantations, at a net cost of $17/tC. As a sensitivity analysis, we consider the effects of varying rainfall (by scaling CVm in proportion to the change in CVnat) and find that the results vary from 30 tC/ha (at $36/tC with 750 mm of rain) to 82 tC/ha (at $13/tC with 1050 mm of rain). These estimates could be applied to projects in areas with different climates.

Ticoporo Reserve

The Ticoporo reserve is a large protected forest area of more than 180,000 ha, decreed by the national government in 1955 for sustainable timber production. The reserve, however, has been illegally occupied by agricultural colonists, especially during the last 20 years. Presently, almost 40% of the forest area has been cleared, mainly for pasture activities. Two private concessions for timber production have been given in two lots of more than 105,000 ha that are relatively well protected from illegal occupancy. In 1993, the Forest Service designed a program to reestablish the forest cover and foster sustainable forest practices in the reserve.

The objective of the program is to establish sustainable forestry systems, using both intensive plantations and agroforestry, in order to stabilize the areaâs land use to limit clearing of the remaining forest. In addition, there are plans to use natural forest management to extract marketable products without intensive harvesting. By converting the dominant land use from unsustainable agriculture to sustainable forestry and agroforestry, Seforven intends to provide incomes for the occupants and maintain the natural resource base. The occupants are expected to implement the forestry activities, with assistance from Seforven.

The project is located in an area with an average annual temperature of 27¼C and rainfall of 1900-2400 mm, and is classified at the humid end of the dry tropical forest life-zone under the Holdridge system (Holdridge, 1967). The soils are somewhat heavy, with poor drainage. Thus, potential agricultural productivity is low, and the most productive land use in most areas is likely to be production forestry and mixed agroforestry systems.

For the plantation projects, net carbon accumulation is from new accumulated biomass and soil and from harvested biomass that enters long-term storage; agroforestry projects can store carbon through these mechanisms as well as by protecting existing forests from potential deforestation. Natural forest management provides carbon accumulation from harvested biomass and protection of existing forests, rather than from new accumulated biomass and soil (Swisher, 1991).

The changes in land-use patterns, and corresponding carbon storage densities, that result from the planned projects can be calculated based on the differences between the plans and the reference case. These two cases show large areas of forest that would have been converted to low-productivity farm and pasture, but instead will be developed into agroforestry, intensive plantations, and both managed and protected natural forest areas. The resulting carbon storage is the difference in carbon densities on the land areas with different types of use between the plan and the reference case.

The areas dedicated to each type of land use at Ticoporo include about 24,000 ha to be developed as plantations and 26,000 ha as agroforestry. An additional 22,000 ha will remain as protected forest reserve land; 16,000 of natural savanna will be protected as wildlife refuge; and the remaining 100,000 ha of natural forest land will be managed to extract marketable timber products while maintaining the forest cover without intensive harvesting (Seforven, 1993). Some of the incentives to be provided by Seforven to promote participation of local communities in the sustainable management of the forest reserve include: planting materials, technical assistance, and direct benefits from wood harvests (plantations and agroforestry components).

We estimate that virtually all 50,000 ha of the area planned for plantations and agroforestry, which are already more than 80% occupied, will be completely deforested in the reference case. Of the 100,000 ha of land planned for natural forest management, it is estimated that without the protection of the forest reserve 40% would be converted to pasture, 30% would become logged secondary forest, and the remaining 30% would remain intact. Of the 22,000 ha of forest land and 16,000 ha of savanna planned for protected reserve, we estimate that 40% would be converted to pasture without the protection of the reserve, 30% would become logged secondary forest, and the remaining 30% stays intact.

For the timber plantation project classification, net carbon accumulation is from new accumulated biomass and soil and from harvested biomass that enters long-term storage. The predominant species in these projects are Tectona grandis (teak), Pinus caribeae (caribbean pine), Cordia alliodora (pardillo, or laurel) and, on the poorer soils with insufficient drainage native hardwoods, Tabebuia rosea (apamate, or savanna oak) and pithecellobium saman (sam‡n, or cenicero). It is estimated that equal areas of each species will be used. Species and management parameters are given in Table IV.5.

Values of carbon density at maturity (CVm) are shown in Table 4 and are based on the values in Table 3 for rotation time and mean annual biomass increment (MABI). Assuming that the biomass remaining at harvest is 15% of CVm, the average ratio of standing biomass to biomass at maturity (Bav/Bm) and the ratio of standing biomass at harvest to biomass at maturity (Bh/Bm) are also shown in Table 4. These values are used to estimate the average accumulated biomass carbon (CVav) above that of the reference (degraded pasture).

Of the biomass harvested at a given time, 70% is useful for timber. Based on a mill efficiency of 50% for this type of project, 35% becomes timber and the remainder may be used for pulp or fuel. Based on the above decay rates, the timber that enters long term storage has a carbon content at steady state as indicated in Table IV.6 (see Cooper, 1983). For this dry tropical forest life zone, the soil carbon storage density in natural forests (CSnat) is 85 tC/ha. Based on the above assumptions of carbon accumulation, the soil carbon storage is given in Table IV.6.

The costs of the projects include materials, plantation, maintenance, infrastructure, vehicles, equipment, forest protection, fire protection, research, education and extension. The costs for agroforestry are assumed to be 60% higher per tree than the costs for plantations, because of additional extension and other costs. Total costs are thus $530/ha for plantations and $400/ha for agroforestry. We add an opportunity cost for the land of $375/ha for plantations and $150/ha for agroforestry, giving a total cost of $905/ha for plantations and $550 for agroforestry.

The resulting total carbon storage values are based on a success rate of 60% in plantations and 70% in agroforestry for this type of project, which is managed by Seforven with high investment and participation of local beneficiaries. The significant challenge is to increase the technical ability of the participants to carry out the forestry activities. The costs per ton are based on the above calculation of $905/ha and $550/ha. Based on a plantation area of 24,000 ha and agroforestry area of 26,000 ha, the carbon storage is 1.3 MtC for the plantations and 0.7 MtC for agroforestry. The total carbon storage is 2 MtC at a net cost for carbon storage of $18/tC.

For the protected forests and savanna reserves, net carbon is stored in the standing biomass and soil on land that is protected from degradation. For this dry tropical forest life zone, the biomass carbon storage density in natural forests (CVnat) is 179 tC/ha, and the soil carbon storage density in natural forests (CSnat) is 85 tC/ha (see Brown and Lugo, 1982 and Swisher, 1991). Thus, a large amount of carbon can be saved by protecting native forests from deforestation and by soil carbon accumulation resulting from forest protection and less intensive land uses than farming and pasture. For the savanna reserve, we assume that the carbon storage densities are approximately the same as in the reference case.

We assume that land converted to pasture would lose 25% of soil carbon and all but 5 tC/ha biomass. Forest land converted to logged secondary forest would lose 10% of soil carbon and 25% of biomass carbon (Brown et al, 1989). Based on the assumed reference land conversion rates given above, the net carbon storage for the forest reserve is thus:

0.4[(179 5) + 85(1 0.75)] + 0.3[179(1 0.75) + 85(1 0.9)] = 94 tC/ha

The cost of the forest reserve is assumed to be the opportunity cost of land, $375/ha. Based on a forest reserve area of 22,000 ha and a savanna reserve area of 16,000 ha, the carbon storage is 2.1 MtC for the forest reserve, at a net cost for carbon storage of $4/tC. For natural forest management, the net carbon storage is from standing biomass and soil and from harvested biomass that enters long term storage. Using the same assumptions of carbon savings as for the forest reserves, and the assumed reference land conversion rates given above, the net carbon storage in standing biomass and soil for managed forest is thus:

0.4[(179 5) + 85(1 0.75)] + 0.3[179(1 0.75) + 85(1 0.9)] = 94 tC/ha

From this result, we subtract an average of 4 tC/ha biomass that is removed as a result of harvesting. Thus, our result is 90 tC/ha.

In addition, some timber extracted from the managed forest (mostly the species Bompacopsis quinnata (saquisaqui or pochote)) enters long term storage. If we use a value for MABI of 1.4 m3/ha yr, of which 70% is useful for timber, a wood density of 0.45 t/m3, and stemwood multiplier of 1.5 for saquisaqui, the timber products have a steady state carbon content value of 5 tC/ha, based on a mill efficiency of 50% and a decay rate of 1.5%/year. With 90 tC/ha of standing biomass and soil, plus 5 tC/ha from harvested products in long term storage and an estimated success rate of 80%, the total net carbon storage is thus 75 tC/ha, or 7.5 MtC for 100,000 ha of natural forest management. The costs for this type of project type are uncertain, but we estimate a total cost of about $700/ha, including opportunity cost of land. This gives a cost for carbon storage of $9/tC.

The total net carbon storage for all the project types is thus 11.6 MtC at an average cost of $10/tC. The costs and carbon storage results for each project type are summarized in Table IV.7.

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