Paul E. Schroeder

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

Aboveground biomass distribution of US eastern hardwood forests and the use of large trees as an indicator of forest development

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

Carbon storage potential of short rotation tropical tree plantations

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

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

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).

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

Abstract Past clearing and harvesting of the deciduous hardwood forests of eastern USA released large amounts of carbon dioxide into the atmosphere, but through recovery and regrowth these forests are now accumulating atmospheric carbon (C). This study examined quantities and distribution of aboveground biomass density (AGBD, Mg ha−1) of US eastern hardwood forests and assessed their biological potential for continued biomass accumulation in the future. Studies have shown that the presence of a large proportion of the AGBD of moist tropical forests in large diameter trees (> 70 cm diameter) is indicative of mature and undisturbed conditions. This relationship was tested as a criterion for the eastern US deciduous forests to assess their stage of recovery and maturity, and evaluate their potential for continued C storage. The approach was to compare AGBD and its distribution in large trees for old-growth forests derived from published studies and for oak-hickory and maple-beech-birch forests using the extensive US Forest Service Forest Inventory and Analysis (FIA) data base. Old-growth forests generally had AGBD of 220–260 Mg ha−1 with up to 30% in trees with diameter > 70 cm. In contrast, maximum AGBD for the FIA units was about 175–185 Mg ha−1 with 8%–10% in large trees. Most units, however, were below these maximum values, suggesting that the forests represented by the FIA inventory are in various stages of recovery from past disturbance. Biologically, therefore, they have the potential to accumulate significant quantities of additional biomass, if left unharvested, and thus storing atmospheric C into the future.

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

Abstract Forests are a major sink for carbon and play an important role in the global carbon cycle. Not only do forests contain huge amounts of carbon, they exchange it very actively with the atmosphere. Expanding the worlds forests, therefore, may present an opportunity to increase the terrestrial carbon sink, and slow the increase in atmospheric CO2 concentration. The tropical zones of the world seem particularly attractive for forestation because of the high rates of productivity that can potentially be attained there, and because there appear to be large areas of land that would benefit from tree planting. The analysis described here examines the carbon storage potential of short rotation tropical tree plantations in particular. Mean long-term carbon storage over multiple rotations was calculated for several commonly grown species. Rotation length, and hence the potential to accumulate biomass, is shown to be a key factor in the ability of plantations to remove carbon from the atmosphere over the long-term.

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

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: II. Biotic fluxes and net carbon balance☆

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

Can intensive management increase carbon storage in forests

33/Mg C.