Belowground Carbon Sequestration Research Articles

Intensive silvopastoral systems with <i>Leucaena leucocephala</i> in Latin America

Plenary paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.Leucaena leucocephala has played a key role in the development of sustainable cattle ranching in Latin America. This species is the backbone of the so-called Intensive Silvopastoral Systems (ISPS) that combine high-density cultivation of leucaena as fodder shrubs (4,000–40,000 plants/ha) with grasses and trees. The layers of vegetation added by shrubs and trees increase the system’s capacity for transforming solar energy into biomass and enhance habitat complexity. Although part of the biomass is transformed into livestock products, a significant amount is deposited as litter on the soil and, along with the nitrogen fixed by leucaena and other trees, has positive effects on soil properties and grass production. The increased complexity of the system has measurable effects on biodiversity. ISPS with leucaena support more species of birds, ants, dung beetles and woody plants than conventional pasture monocultures, contribute to landscape-scale connectivity and provide environmental services. They also enhance animal welfare through reduced heat stress and improved availability and quality of fodder resources. ISPS contribute to climate change mitigation by improving above- and below-ground carbon sequestration and by cutting down greenhouse gas emissions per units of dry matter consumed and cattle product. Although these systems have been successfully implemented in Colombia, Mexico and other countries, their adoption is still limited in relation to the area suitable for their introduction.

Habitat evolution of a peat swamp forest and belowground carbon sequestration during the Holocene along the coastal lowland in Central Sumatra, Indonesia

Habitat evolution of a peat swamp forest and belowground carbon storage was examined in a coastal lowland along the eastern coast of Central Sumatra, Indonesia. Boring surveys using a hand-operated peat sampler for 32 sites and radiocarbon dating for 29 samples revealed that the peat swamp forest had begun formation by 6500 cal BP and expanded rapidly between 6500 and 5000 cal BP and between 4000 and 2000 cal BP to nearly the present distribution area. The thickness of the peat layer formed under the peat swamp forest reached approximately 4 m, even in the margin of the peat dome, and more than 9 m in the center. Stored carbon per unit volume of the peat layer was estimated to be between 30 and 44 kg C m−3 in the margin of the peat dome and approximately 26 kg C m−3 in the center, which was less than the general carbon values of the mangrove peat. The relatively higher amount of stored carbon per unit volume in the margin was possibly caused by an inflow of allochthonous carbon from flood deposits. Belowground carbon burial rate of the peat layer was calculated as between 31 and 105 g C m−2 years−1 in the peat dome margin and between 27 and 76 g C m−2 years−1 in the center, which were identical to mangrove peat. These data suggest that peat swamp forests have played a significant role as places for carbon sequestration belowground as well as mangrove forest with mangrove peat.

Evaluation of Carbon Sequestration and Global Warming Potential of Wheat in Khorasan-Razavi province

In order to determine soil characteristics and above-ground and below-ground carbon sequestration potential of wheat, a systematic random sampling method was employed to select 5 samples from 50 fields situated in Khorasan-Razavi Province, Iran during 2015. The experimental design was a completely randomized design with three replications. The ash method was used to determine the carbon sequestration conversion coefficients in spikes, stems, leaves and roots. Then, greenhouse gases (such as CO2, N2O and CH4) emission were calculated using emission coefficients. The average organic carbon, total nitrogen, available phosphorus, available potassium, soil bulk density, pH and electrical conductivity were found to be 0.98%, 0.02%, 27.07 ppm, 341.32 ppm, 1.37 g.cm-3, 7.81 and 1.42 dS.m-1, respectively. The maximum (52.0%) and minimum (31.99%) conversion coefficients were related to spikes (seeds included) and roots, respectively. In addition, the total carbon sequestration was 8.25 t.ha-1 so that the maximum (4.28 t.ha-1) and minimum (0.35 t.ha-1) values were found in stems and roots, respectively. The total global warming potential (GWP) of wheat was recorded as 2377.86 kg CO2 –equiv. per ton of seed. The first contributing factor was nitrogen fertilizers, accounting for 1331.30 kg CO2 –equiv. per ton of seed.

Accumulation of soil organic C and N in planted forests fostered by tree species mixture

Abstract. With the increasing trend of converting monocultures into mixed forests, more and more studies have been carried out to investigate the admixing effects on tree growth and aboveground carbon storage. However, few studies have considered the impact of mixed forests on belowground carbon sequestration, particularly changes in soil carbon and nitrogen stocks as a forest grows. In this study, paired pure Pinus massoniana plantations, Cinnamomum camphora plantations and mixed Pinus massoniana–Cinnamomum camphora plantations at ages of 10, 24 and 45 years were selected to test whether the mixed plantations sequestrate more organic carbon (OC) and nitrogen (N) in soils and whether this admixing effect becomes more pronounced with stand ages. The results showed that tree species identification, composition and stand age significantly affected soil OC and N stocks. The soil OC and N stocks were the highest in mixed Pinus–Cinnamomum stands compared to those in counterpart monocultures with the same age in the whole soil profile or specific soil depth layers (0–10, 10–20 and 20–30 cm) for most cases, followed by Cinnamomum stands and Pinus stands with the lowest. These positive admixing effects were mostly nonadditive. Along the chronosequence, the soil OC stock peaked in the 24-year-old stand and was maintained as relatively stable thereafter. The admixing effects were also the highest at this stage. However, in the topsoil layer, the admixing effects increased with stand ages in terms of soil OC stocks. When comparing mixed Pinus–Cinnamomum plantations with corresponding monocultures within the same age, the soil N stock in mixed stands was 8.30, 11.17 and 31.45 % higher than the predicted mean value estimated from counterpart pure species plantations in 10-, 24- and 45-year-old stands, respectively. This suggests that these admixing effects were more pronounced along the chronosequence.

Positive interactions between Pinus massoniana and Castanopsis hystrix species in the uneven-aged mixed plantations can produce more ecosystem carbon in subtropical China

Abstract Silvicultural practices are an important determinant of tree growth and stand structure. However, the potential advantages of long-term forest management, i.e., mixing valuable non-N 2 -fixing broadleaf tree species, such as Castanopsis hystrix Miq., with Masson pine ( Pinus massoniana Lamb.) to increase stand growth and ecosystem carbon storage, remain poorly understood. In this study, we assessed tree growth, aboveground carbon accumulation, and belowground carbon sequestration in 26-year-old monocultures of C . hystrix ( 100 C 26 ), 26-year-old monocultures of P . massoniana ( 100 P 26 ), 50-year-old monocultures of P . massoniana ( 100 P 50 ), and even- and uneven-aged ( 50 C 26 + 50 P 26 and 50 C 26 + 50 P 50 , respectively) mixed plantations. Carbon storage within the total ecosystem and in the tree and soil layers of 50 C 26 + 50 P 50 mixed plantations was significantly greater than values predicted based on the means of the 100 C 26 and 100 P 50 monoculture plantations ( p 50 C 26 + 50 P 26 mixed plantation soils. These results indicate that plantations of uneven-aged mixtures of P . massoniana and C . hystrix promote carbon sequestration via positive interactions.

Belowground carbon sequestration in a mature planted mangroves (Northern Viet Nam)

Abstract Mangroves play a key role in carbon sequestration along tropical and subtropical coastlines, mainly as a result of their high primary productivity and the anoxic character of their soils, in which organic matter decay processes are slow. Unfortunately, these forests are disappearing worldwide, notably due to aquaculture and the need for space on the shoreline. The mangrove area in Viet Nam decreased substantially until late 90’s, which was a concern for the Vietnamese government. Then, replantation programs were developed in order to protect the shoreline against the erosion; like in northern Viet Nam, where monospecific stands were planted from the mid 90’s. Within this context, our objectives were to determine carbon stocks and carbon burial rates in the soil of a 18 years old Kandelia obovata (Sheue, Lui & Yong) mangrove forest. Three plots were set up in the planted mangroves and three in adjacent bare land (without any mangrove) at the mouth of Red River. Three geo-slicers up to 100 cm depth were taken in each plot; and in each core, ten soil samples were collected with a 10 cm depth interval. Later on, dead and live roots were sorted. Carbon contents in soils and in roots were determined using the Walkley-Black method and loss on ignition (LOI) method, respectively. Then, the total belowground carbon sequestration was estimated. There was a depth related distribution of organic carbon in soil with the highest concentrations measured between 20 and 60 cm depth. Accumulated carbon up to depth of 100 cm in soil and roots of the planted K. obovata were 146.78 ± 3.87 Mg OC ha −1 and 12.67 ± 0.14 Mg OC ha −1 , respectively. The value was 87.59 ± 1.08 Mg OC ha −1 for the adjacent bare land. Consequently, the mean carbon burial rate for this system was approximately 6.94 Mg OC ha −1 yr −1 , which is higher than most of the mangroves and may be related to a low export of the net primary productivity or most likely to a high sedimentation rate. These results were compared with previously published results on carbon stocks in younger planted forests of the same species in the same region, a positive and linear relationship was determined between the age of the planted stand and the belowground carbon stocks.

The contrasting effects of nutrient enrichment on growth, biomass allocation and decomposition of plant tissue in coastal wetlands

Eutrophication of coastal waters can have consequences for the growth, function and soil processes of coastal wetlands. Our aims were to assess how nutrient enrichment affects growth, biomass allocation and decomposition of plant tissues of a common and widespread mangrove, Avicennia marina, and how eutrophication drives changes in below-ground carbon sequestration. We assessed this through the measurement of above- and belowground growth and decomposition rates of plants and plant tissue in unenriched or nutrient enriched treatments. Nutrient enrichment increased biomass allocation above-ground compared to below-ground in seedlings but not in fully developed, mature trees where we observed the opposite pattern. Experiments to assess root decomposition found that 40–50% of biomass was lost within six months with little change between 12 and 18 months, indicating a high potential for accumulation of organic matter over time. We estimate root-derived carbon sequestration rates of 53, 250 and 94 g C m−2 year−1 for unenriched control, N and P enriched treatments, respectively. These results show coastal eutrophication can be beneficial and detrimental to ecosystem function of coastal plants. Eutrophication stimulates root growth in fully developed trees, increasing organic matter input to soils. Our data suggests that organic matter accumulation will increase in areas with high nutrient availability where root growth is increased and rates of decomposition are low.

Electrical capacitance as a predictor of root dry weight in shrub willow (Salix; Salicaceae) parents and progeny.

Premise of the study:Root biomass is an important trait often disregarded in woody perennial selection due to the challenge and expense of accurately and efficiently measuring large populations. In this study, we aim to develop a simple method that can predict root dry weight within a diverse shrub willow (Salix) breeding population representing species hybrids and their parents using root electrical capacitance (REC).Methods:The REC method was tested on plants started from cuttings and grown in pots with potting mix in the greenhouse for 11 wk to assess the relationship of REC with 24 biomass traits and its usefulness in allometric models for root and stem dry biomass.Results:Strong linear and positive correlations were found between REC and root dry biomass (r = 0.88). The total proportion of variance of root and stem dry biomass explained by predictors in multiple regression was 85% and 69%, respectively. The relative importance of predictor variables in allometric models was dominated by the contribution of REC.Discussion:This work provides an efficient and nondestructive technique to indirectly quantify root biomass of genetically diverse shrub willow progeny, which has great promise for selection of genotypes with varying root biomass and for the accurate estimation of belowground carbon sequestration.

Marginal effects on biodiversity, carbon sequestration and nutrient cycling of transitions from tropical forests to cacao farming systems

Cacao (Theobroma cacao), a perennial crop predominantly cultivated as a multi-product and multi-strata agroforestry system, has been identified as one of an array of factors behind land use changes in the tropics. Concerns have also been raised about the gradual shift from traditional cacao growing systems under diverse and dense tree canopy to lower or no-shade cover, leading to further loss of direct and functional forest ecosystem values such as protective and regulatory environmental services. This paper surveys existing literature and focuses on changes to biodiversity, carbon sequestration and nutrient cycling conditions due to a transition from natural forests to traditional lower-density agroforestry and high-density hybrid monoculture cacao systems. We derive marginal effects on selected ecosystem functions expressed as a percentage unit change in corresponding ecosystem values from a natural forest baseline scenario. Data from 16 studies conducted in Africa and the Americas show a negative trend in marginal changes in above-and below-ground carbon sequestration potential for the two cacao farming systems. The extent of marginal losses in carbon storage was comparatively higher for the monoculture than cacao agroforestry system. A general trend denoting positive marginal changes has been reported for mean species richness in soil and litter and some essential chemical and physical soil properties (Calcium, Magnesium, sand and silt) of cacao agroforestry systems compared with a natural forest baseline. The balance between negative and positive changes show that traditional cacao agroforestry systems have greater potential for conservation of ecosystem services closer to a natural forest state than monocultures.

Ecosystem-Service Tradeoffs Associated with Switching from Annual to Perennial Energy Crops in Riparian Zones of the US Midwest

Integration of energy crops into agricultural landscapes could promote sustainability if they are placed in ways that foster multiple ecosystem services and mitigate ecosystem disservices from existing crops. We conducted a modeling study to investigate how replacing annual energy crops with perennial energy crops along Wisconsin waterways could affect a variety of provisioning and regulating ecosystem services. We found that a switch from continuous corn production to perennial-grass production decreased annual income provisioning by 75%, although it increased annual energy provisioning by 33%, decreased annual phosphorous loading to surface water by 29%, increased below-ground carbon sequestration by 30%, decreased annual nitrous oxide emissions by 84%, increased an index of pollinator abundance by an average of 11%, and increased an index of biocontrol potential by an average of 6%. We expressed the tradeoffs between income provisioning and other ecosystem services as benefit-cost ratios. Benefit-cost ratios averaged 12.06 GJ of additional net energy, 0.84 kg of avoided phosphorus pollution, 18.97 Mg of sequestered carbon, and 1.99 kg of avoided nitrous oxide emissions for every $1,000 reduction in income. These ratios varied spatially, from 2- to 70-fold depending on the ecosystem service. Benefit-cost ratios for different ecosystem services were generally correlated within watersheds, suggesting the presence of hotspots – watersheds where increases in multiple ecosystem services would come at lower-than-average opportunity costs. When assessing the monetary value of ecosystem services relative to existing conservation programs and environmental markets, the overall value of enhanced services associated with adoption of perennial energy crops was far lower than the opportunity cost. However, when we monitized services using estimates for the social costs of pollution, the value of enhanced services far exceeded the opportunity cost. This disparity between recoverable costs and social value represents a fundamental challenge to expansion of perennial energy crops and sustainable agricultural landscapes.

Comparing fast- and slow-growing provenances of Picea koraiensis in biomass, carbon parameters and their relationships with growth

Tree genetic selection programs are primarily focused on improving stem volume plantation productivity. Due to changes in climate and emergence of carbon (C) market, plantations are also being credited for total biomass productivity and C sequestration. Does growth selection adversely affect total above- and belowground biomass and C sequestration? We investigated this by comparing two fast-growing provenances (LS and CH) to a slow-growing provenance (KT) from a 31-year-old Picea koraiensis experiment. Results showed that (1) the fast-growing provenances could enhance both above- and belowground biomass productivity and carbon sequestration. On average, trees of LS and CH provenances produced 16.1% and 31.8% more biomass and had 17.2% and 31.8% more C stock, respectively, than KT provenance, although these differences were statistically non-significant (P<0.10). The fast-growing provenances displayed a comparable to or even slightly higher C concentration than KT provenance; (2) growth selection influenced biomass and C partitioning. Compared to KT, the CH and LS allocated relatively more to stem wood but less to the needles and branches aboveground and partitioned more to the stump and coarse roots but less to the fine and medium size roots belowground. The fast-growing provenances had a very similar or lower above- to belowground biomass partitioning slope. Thus, the superiority of the aboveground growth of LS and CH was not achieved at the expense of belowground compartments; and (3) the best function to predict biomass and C content was ‘a(DBH2H)b’. Fitting provenance-specific relationship parameter (a or b) improved prediction precision. This was particularly true for b and for the biomass of branches, aboveground and whole tree. Overall our results suggest the possibility of improving biomass productivity and C sequestration via planting growth-improved seed sources. Implications to tree improvement are discussed.

Species mixing boosts root yield in mangrove trees

Enhanced species richness can stimulate the productivity of plant communities; however, its effect on the belowground production of forests has scarcely been tested, despite the role of tree roots in carbon storage and ecosystem processes. Therefore, we tested for the effects of tree species richness on mangrove root biomass: thirty-two 6 m by 6 m plots were planted with zero (control), one, two or three species treatments of six-month-old Avicennia marina (A), Bruguiera gymnorrhiza (B) and Ceriops tagal (C). A monoculture of each species and the four possible combinations of the three species were used, with four replicate plots per treatment. Above- and belowground biomass was measured after three and four years' growth. In both years, the all-species mix (ABC) had significant overyielding of roots, suggesting complementarity mediated by differences in rhizosphere use amongst species. In year four, there was higher belowground than aboveground biomass in all but one treatment. Belowground biomass was strongly influenced by the presence of the most vigorously growing species, A. marina. These results demonstrate the potential for complementarity between fast- and slow-growing species to enhance belowground growth in mangrove forests, with implications for forest productivity and the potential for belowground carbon sequestration.

氮沉降对森林生态系统碳吸存的影响

工业化带来的大气氮沉降增加是影响森林生态系统碳吸存的重要因素。将森林碳库分为地上和地下两部分,从3个方面综述了国内外氮沉降对森林生态系统碳吸存影响的研究现状。(1)地上部分:氮限制的温带森林,氮沉降增加了地上部分碳吸存。氮丰富的热带森林,氮沉降对地上部分碳吸存没有影响。过量的氮输入会造成森林死亡率的上升,从而降低地上部分碳吸存。(2)地下部分:相比地上部分研究得少,表现为增加、降低和没有影响3种效果。(3)目前的结论趋向于认为氮沉降促进森林生态系统碳吸存,然而氮沉降所带来的森林生态系统碳吸存能力到底有多大依然无法确定,这也将成为未来氮碳循环研究的重点问题。分析了氮沉降影响森林生态系统碳吸存的机理,介绍了氮沉降对森林生态系统碳吸存影响的4种研究方法。探讨了该领域研究的不足及未来的研究方向。;Human activities such as combustion of fossil fuels, intensive agriculture and stockbreeding, have significantly altered the global nitrogen (N) cycle in the last several decades, resulting in increasing the concentrations of nitrogenous compounds in the atmosphere and elevating N deposition to the terrestrial ecosystems. Greater N deposition may change the carbon sequestration on forest ecosystems through affecting the plant growth, litter production, fine root turnover, recalcitrance of N-enriched litter, microbial growth and the DOC dynamic, and has been increasingly concerned worldwide. Based on the available literature, we divided forest carbon pool into aboveground and belowground carbon pool, reviewed the impacts of N deposition on forest carbon sequestration, emphasizing three aspects: (1) Aboveground carbon sequestration. N deposition increase carbon sequestration in N-limited temperate forests or have no effects on N-Saturation tropical forest, but high N deposition may have negative effects by rising forest mortality. (2) Belowground carbon sequestration. The results of reports are different, ranging from positive to negative depending on forest type, and have few regulation because of its limited researches compared with the researches in aboveground carbon sequestration. (3) The dispute. A range of studies have showed positive carbon increase under N deposition, but the degree of the effects is highly uncertain and may vary by two orders of magnitude. We also reviewed the mechanisms and research methods about the effects of N deposition on forest carbon sequestration in this paper. Finally, the present and future research needs about the effects of N deposition are also discussed.

Effects of increased forest productivity and warmer climates on carbon sequestration, run-off water quality and accumulation of dead wood in a boreal landscape: A modelling study

Forest productivity is expected to increase in the future owing to the use of genetically improved plant material and climate warming. Increased productivity will lead to shorter optimum rotation lengths and larger annual clear-cut areas. This study explored the likely effects of increased forest production and a warmer climate in 15 scenarios (five productivity levels and three climate conditions) on: (1) wood production, (2) carbon sequestration, (3) water quality, and (4) amounts of coarse woody debris (CWD). The effects were simulated using a set of ecosystem models incorporating the same climate and management scenarios in a hypothetical managed boreal forest landscape. Under the assumption that increased productivity is coupled to a proportional decrease in rotation length, the outputs at the landscape-level scale were briefly as follows. In each simulated climate scenario, increased productivity resulted in increases in above- and below-ground carbon sequestration, and reduced CWD accumulation, but did not have significant effects on dissolved total nitrogen (DTN) loads in run-off water. In addition, at every simulated productivity level, a warmer climate led to reductions in carbon sequestration below ground and amounts of CWD, but increases in DTN contents in run-off water. Reasons for these trends are identified and explained.

Wheat root dynamics as affected by landscape position

The effects of landscape position on root production and mortality were assessed in a 90-cm-deep soil profile at a shoulder and footslope landscape position seeded to spring wheat (Triticum aestivum L.). Root length was measured over eight sampling dates using a minirhizotron system, and soil water content and temperature were recorded at various depths at each landscape position. The shoulder position was drier than the footslope position in the upper 30 cm due to a greater frequency and duration of soil temperatures &gt; 20°C, and at depth (&gt; 75 cm). Mean root length was greatest at the footslope position and was concentrated in the upper 20 cm of the profile, while the shoulder position had the greatest root length at the 40- to 60-cm depth. Mean daily root production peaked at 5.0 to 6.0 m m-2 d-1 at the 43rd day after planting (DAP) for both landscape positions, which corresponded to the time of booting. Daily rates for root mortality ranged from 0.5 to 2.5 m m-2 d-1. Soil water content and daily root production at the 10-cm depth were positively correlated at both landscape positions. Information on landscape position differences in root productivity and mortality could help to improve placement of inorganic fertilizers, and estimation of below-ground carbon sequestration. Key words: Wheat, roots, minirhizotron, landscape position

Forest production responses to irrigation and fertilization are not explained by shifts in allocation

Production increases in intensively managed forests have been obtained by improving resource availability through water and nutrient amendments. Increased stem production has been attributed to shifts in growth from roots to shoot, and such shifts would have important implications for belowground carbon sequestration. We examined above and belowground growth and biomass accumulation and distribution in two eastern cottonwood clones and American sycamore receiving irrigation (I), fertilization (F), or irrigation + fertilization (IF) and compared with non-treated controls (C). Aboveground growth and biomass accumulation responded positively to both I and F in all genotypes. After three growing seasons, the largest trees were sycamore receiving the IF treatment, with a total mean annual biomass production of 9.4 Mg ha −1 yr −1. Total cottonwood mean annual biomass production in both clones was >5.0 Mg ha −1 yr −1 in the IF treatment. Aboveground biomass production was 6.3 and >3.1 Mg ha −1 yr −1 for sycamore and cottonwoods, respectively. Total root mass fraction was lower in high resource treatments and declined as stands aged. To compare allocation in trees of equal size, we used allometric relationships between above and belowground tissue. Allometric relationships between woody perennial tissues rarely differed among treatments. Improved resource availability caused large increases in growth and consequently accelerated development, but it had little effect on belowground allocation that was not explained by development. Reports of shifting belowground allocation due to soil resource availability must account for developmental effects if they are to accurately evaluate direct impacts of soil resources.

Moss and lichen cover mapping at local and regional scales in the boreal forest ecosystem of central Canada

Mosses and lichens are important components of boreal landscapes [Vitt et al., 1994; Bubier et al., 1997]. They affect plant productivity and belowground carbon sequestration and alter the surface runoff and energy balance. We report the use of multiresolution satellite data to map moss and lichens over the BOREAS region at a 10 m, 30 m, and 1 km scales. Our moss and lichen classification at the 10 m scale is based on ground observations of associations among soil drainage classes, overstory composition, and cover type among four broad classes of ground cover (feather, sphagnum, and brown mosses and lichens). For our 30 m map, we used field observations of ground cover‐overstory associations to map mosses and lichens in the BOREAS southern study area (SSA). To scale up to a 1 km (AVHRR) moss map of the BOREAS region, we used the TM SSA mosaics plus regional field data to identify AVHRR overstory‐ground cover associations. We found that: 1) ground cover, overstory composition and density are highly correlated, permitting inference of moss and lichen cover from satellite‐based land cover classifications; 2) our 1 km moss map reveals that mosses dominate the boreal landscape of central Canada, thereby a significant factor for water, energy, and carbon modeling; 3) TM and AVHRR moss cover maps are comparable; 4) satellite data resolution is important, particularly in detecting the smaller wetland features, lakes, and upland jack pine sites; and 5) distinct regional patterns of moss and lichen cover correspond to latitudinal and elevational gradients.

The Potential for Carbon Sequestration Through Reforestation of Abandoned Tropical Agricultural and Pasture Lands

AbstractApproximately half of the tropical biome is in some stage of recovery from past human disturbance, most of which is in secondary forests growing on abandoned agricultural lands and pastures. Reforestation of these abandoned lands, both natural and managed, has been proposed as a means to help offset increasing carbon emissions to the atmosphere. In this paper we discuss the potential of these forests to serve as sinks for atmospheric carbon dioxide in aboveground biomass and soils. A review of literature data shows that aboveground biomass increases at a rate of 6.2 Mg ha−1 yr−1 during the first 20 years of succession, and at a rate of 2.9 Mg ha−1 yr−1 over the first 80 years of regrowth. During the first 20 years of regrowth, forests in wet life zones have the fastest rate of aboveground carbon accumulation with reforestation, followed by dry and moist forests. Soil carbon accumulated at a rate of 0.41 Mg ha−1yr−1 over a 100‐year period, and at faster rates during the first 20 years (1.30 Mg carbon ha−1 yr−1). Past land use affects the rate of both above‐ and belowground carbon sequestration. Forests growing on abandoned agricultural land accumulate biomass faster than other past land uses, while soil carbon accumulates faster on sites that were cleared but not developed, and on pasture sites. Our results indicate that tropical reforestation has the potential to serve as a carbon offset mechanism both above‐ and belowground for at least 40 to 80 years, and possibly much longer. More research is needed to determine the potential for longer‐term carbon sequestration for mitigation of atmospheric CO2 emissions.