Jack K. Winjum

Estimating the global potential of forest and agroforest management practices to sequester carbon

Forests play a prominent role in the global C cycle. Occupying one-third of the earths land area, forest vegetation and soils contain about 60% of the total terrestrial C. Forest biomass productivity can be enhanced by management practices, which suggests that, by this means, forests could store more C globally and thereby slow the increase in atmospheric CO2. The question is how much C can be sequestered by forest and agroforest management practices. To address the question, a global database of information was compiled to assess quantitatively the potential of forestry practices to sequester C. The database presently has information for 94 forested nations that represent the boreal, temperate and tropical latitudes. Results indicate that the most promising management practices are reforestation in the temperate and tropical latitudes, afforestation in the temperate regions, and agroforestry and natural reforestation in the tropics. Across all practices, the median of the mean C storage values for the boreal latitudes is 16 tCha[−1 (n=46) while in the temperate and tropical latitudes the median values are 71 tCha−1 (n=401) and 66 tCha−1 (n=170), respectively. Preliminary projections are that if these practices were implemented on 0.6 to 1.2×109 ha of available land over a 50-yr period, approximately 50 to 100 GtC could be sequestered.

Integrated Land-Use Systems: Assessment of Promising Agroforest and Alternative Land-Use Practices to Enhance Carbon Conservation and Sequestration

Degraded or sub-standard soils and marginal lands occupy a significant proportion of boreal, temperate and tropical biomes. Management of these lands with a wide range of existing, site-specific, integrated, agroforest systems represents a significant global opportunity to reduce the accumulation of greenhouse gases in the atmosphere. Establishment of extensive agricultural, agroforest, and alternative land-use systems on marginal or degraded lands could sequester 0.82–2.2 Pg carbon (C) per year, globally, over a 50-year time-frame. Moreover, slowing soil degradation by alternative grassland management and by impeding desertification could conserve up to 0.5–1.5 Pg C annually. A global analysis of biologic and economic data from 94 nations representing diverse climatic and edaphic conditions reveals a range of integrated land-use systems which could be used to establish and manage vegetation on marginal or degraded lands. Promising land-use systems and practices identified to conserve and temporarily store C include agroforestry systems, fuelwood and fiber plantations, bioreserves, intercropping systems, and shelterbelts/windbreaks. For example, successful establishment of low-intensity agroforestry systems can store up to 70 Mg C/ha in boreal, temperate and tropical ecoregions. The mean initial cost of soil rehabilitation and revegetation ranges from

Forest plantations of the world: their extent, ecological attributes, and carbon storage

500–3,000/ha for the 94 nations surveyed. Natural regeneration of woody vegetation or agro-afforestation establishment costs were less than

Forest Management and Carbon Storage: An Analysis of 12 Key Forest Nations

1000/ha in temperate and tropical regions. The costs of C sequestration in soil and vegetation systems range from

Conservation and sequestration of carbon: The potential of forest and agroforest management practices☆

1-69/Mg C, which compares favorably with other options to reduce greenhouse gas emissions to the atmosphere. Although agroforestry system projects were recently established to conserve and sequester C in Guatemala and Malaysia, constraints to wide-spread implementation include social conditions (demographic factors, land tenure issues, market conditions, lack of infrastructure), economic obstacles (difficulty of demonstrating benefits of alternative systems, capital requirements, lack of financial incentives) and, ecologic considerations (limited knowledge of impacts and sustainability of some systems).

Biomass management and energy

Abstract Forest plantations in the world total approximately 130 X 106 ha, and annual rates of establishment are about 10.5 X 106 ha. A total of 124 countries throughout the high, middle, and low latitudes of the world establish new plantations each year. In addition to supplying an array of goods and services, plantations contribute to carbon (C) storage. This analysis integrates information across latitudes to evaluate the potential of forest plantations to achieve these goals. For example, mean carbon storage (MCS) in above- and below-ground phytomass of artificially established plantations generally increases from high to low latitudes ranging from 47 to 81 t C ha−1. Over a 50-year period, harvests from these plantations are credited with storing C at 10, 34, 15, and 37 t C ha−1 in wood products in the high, middle, low-dry, and low-moist latitudes, respectively. Using todays distribution of plantations among the four zones of latitude and C storage values from this analysis, the worlds plantations can be credited with storing an area-weighted average of 91 t C ha−1 including MCS and durable-wood products. Based upon these estimates, the world total C storage in forest plantations today is approximately 11.8 Pg C with an annual increase of 0.178 Pg C year−1.

Assessing Brazil's carbon budget: I. Biotic carbon pools

Forests of the world sequester and conserve more C than all other terrestrial ecosystems and account for 90% of the annual C flux between the atmosphere and the Earths land surface. Preliminary estimates indicate that forest and agroforest management practices throughout the world can enhance the capability of forests to sequester C and reduce accumulation of greenhouse gases in the atmosphere. Yet of the 3600 × 106 ha of forests in the world today, only about 10% (350×106 ha) are actively managed. The impetus to expand lands managed for forestry or agroforestry purposes lies primarily with nations having forest resources. In late 1990, an assessment was initiated to evaluate the biological potential and initial site costs of managed forest and agroforest systems to sequester C. Within the assessment, 12 key forested nations were the focus of a special analysis: Argentina, Australia, Brazil, Canada, China, Germany, India, Malaysia, Mexico, South Africa, former USSR, and USA. These nations contain 59% of the worlds natural forests and are representative of the worlds boreal, temperate, and tropical forest biomes. Assessment results indicate that though the worlds forests are contained in 138 nations, a subset of key nations, such as the 12 selected for this analysis, can significantly contribute to the global capability to sequester C through managed tree crops. Collectively, the 12 nations are estimated to have the potential to store 25.7 Pg C, once expanded levels of practices such as reforestation, afforestation, natural regeneration and agroforestry are implemented and maintained. Initial site costs based upon establishment costs for management practices are less than US

Assessing Brazil's carbon budget: II. Biotic fluxes and net carbon balance☆

33/Mg C.

An inventory-based procedure to estimate economic costs of forest management on a regional scale to conserve and sequester atmospheric carbon

Abstract Forests play a major role In Earths carbon cycle through assimilation, storage, and emission of CO 2 . Establishment and management of boreal, temperate, and tropical forest and agroforest systems could potentially enhance sequestration of carbon in the terrestrial biosphere. A biological and economic analysis of forest establishment and management options from 94 nations revealed that forestation, agroforestry, and silviculture could be employed to conserve and sequester one Petagram (Pg) of carbon annually over a 50-year period. The marginal cost of implementing these options to sequester 55 Pg of carbon would be approximately

Terrestrial Carbon Dynamics: Case Studies in the Former Soviet Union, the Conterminous United States, Mexico and Brazil

10/Mg.