Net Carbon Storage Research Articles

Effect of understory on a natural secondary forest ecosystem carbon budget

Lacking of detail data, forest carbon stock estimation with forest inventory data usually excludes or underestimates understory carbon storage. To quantify the effects of understory on carbon sequestration in a natural secondary Pinus tabulaeformis forest, organ biomass models for arbor, shrub to their growth indices were regressed. Biomass of herbage was estimated in a stratified sampling method. Soil respiration in forest land was measured. Based on above data, carbon budget of Pinus tabulaeformis forest was assessed as 1.882 CO2 Mghm−2year−1, 37.04% of the entire vegetation’s yearly net carbon storage belonging to understory.

Differential response of carbon fluxes to climate in three peatland ecosystems that vary in the presence and stability of permafrost

Changes in vegetation and soil properties following permafrost degradation and thermokarst development in peatlands may cause changes in net carbon storage. To better understand these dynamics, we established three sites in Alaska that vary in permafrost regime, including a black spruce peat plateau forest with stable permafrost, an internal collapse scar bog formed as a result of thermokarst, and a rich fen without permafrost. Measurements include year-round eddy covariance estimates of carbon dioxide (CO2), water, and energy fluxes, associated environmental variables, and methane (CH4) fluxes at the collapse scar bog. The ecosystems all acted as net sinks of CO2 in 2011 and 2012, when air temperature and precipitation remained near long-term means. In 2013, under a late snowmelt and late leaf out followed by a hot, dry summer, the permafrost forest and collapse scar bog were sources of CO2. In this same year, CO2 uptake in the fen increased, largely because summer inundation from groundwater inputs suppressed ecosystem respiration. CO2 exchange in the permafrost forest and collapse scar bog was sensitive to warm air temperatures, with 0.5 g C m−2 lost each day when maximum air temperature was very warm (≥29°C). The bog lost 4981 ± 300 mg CH4 m−2 between April and September 2013, indicating that this ecosystem acted as a significant source of both CO2 and CH4 to the atmosphere in 2013. These results suggest that boreal peatland responses to warming and drying, both of which are expected to occur in a changing climate, will depend on permafrost regime.

Determining suitable selection cutting intensities based on long-term observations on aboveground forest carbon, growth, and stand structure in Changbai Mountain, Northeast China

We studied the effects of different cutting intensities (0%, 5–10%, 15%, and 20% basal area removal) on stand growth, structure, and net carbon storage in spruce–fir (Picea jezoensis (Sieb. et Zucc.) Carr.–Abies nephrolepis (Trautv.) Maxim.) and broadleaf mixed forests on Changbai Mountain (Northeast China) over 19 years. At this site, inventory-based low-intensity selection cutting was used to maintain a continuous forest canopy. After two cutting events, results showed significant differences in growth, structure, and carbon storage among cutting intensities. When increasing cutting intensity, the growth rate of average diameter, basal area, and volume significantly increased, with the highest increment rates found in the plots with 20% basal area removal. Tree diameters for all plots showed a roughly inverse J-shaped distribution before cutting and a left-skewed unimodal distribution after two cuttings. Volume ratio (the relative amount of volume contained in different diameter classes) for small (6–14 cm), medium (14–26 cm), large (26–36 cm), and very large (>38 cm) diameters remained unchanged in the plots with 5 and 10% basal area removal, but the volume ratio of large and very large diameters increased in the plots with 15 and 20% basal area removal, reaching approximately a 1:2:3:4 ratio in the plots with 20% basal area removal after two selection cuttings. Net carbon storage increased when increasing cutting intensity, reaching maximum storage in the plots with 20% basal area removal (cutting intensity and net C storage increase: 0%, 7.21 Mg C ha−1, 5–10%: 11.68 Mg C ha−1, 15%: 21.41 Mg C ha−1, 20%: 26.47 Mg C ha−1). Therefore, our results show the potential of low-intensity selection cutting to meet demands of both timber production and maintenance of forest cover for biodiversity values.

Net carbon storage measured in a mowed and grazed temperate sown grassland shows potential for carbon sequestration under grazed system

Background: Managed temperate grassland has the potential to sequester carbon if management practices are improved. In this study, CO2 flux was measured by the eddy covariance technique in two identical temperate sown grasslands under different managements, viz. mowing and grazing, to estimate and compare net carbon storage under both the management systems.Results: In both mowing and grazing systems, the averaged annual gross plant productivity, ecosystem respiration and net ecosystem exchange were –1720 and –1741, 1244 and 1510, and –476 and –231 g C m–2 year–1, respectively. Although the management practices did not significantly influence gross plant productivity (p > 0.05), grazing system increased Reco significantly by 21% (p < 0.05) but reduced net ecosystem exchange by 52% (p < 0.05) compared to mowing system. However, averaged annual net carbon storage were 23 and 141 g C m–2 year–1 under mowing and grazing, respectively.Conclusion: The results indicate that temperate sown grassland has the potential to sequester carbon under grazing.

Agricultural conversion without external water and nutrient inputs reduces terrestrial vegetation productivity

AbstractDriven by global population and standard of living increases, humanity co‐opts a growing share of the planet's natural resources resulting in many well‐known environmental trade‐offs. In this study, we explored the impact of agriculture on a resource fundamental to life on Earth: terrestrial vegetation growth (net primary production; NPP). We demonstrate that agricultural conversion has reduced terrestrial NPP by ~7.0%. Increases in NPP due to agricultural conversion were observed only in areas receiving external inputs (i.e., irrigation and/or fertilization). NPP reductions were found for ~88% of agricultural lands, with the largest reductions observed in areas formerly occupied by tropical forests and savannas (~71% and ~66% reductions, respectively). Without policies that explicitly consider the impact of agricultural conversion on primary production, future demand‐driven increases in agricultural output will likely continue to drive net declines in global terrestrial productivity, with potential detrimental consequences for net ecosystem carbon storage and subsequent climate warming.

Rate of tree carbon accumulation increases continuously with tree size

Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

Toward full economic valuation of forest fuels-reduction treatments

Our goal was to move toward full economic valuation of fuels-reduction treatments applied to ponderosa pine (Pinus ponderosa) forests. For each of five fuels-reduction projects in northern Arizona, we calculated the economic value of carbon storage and carbon releases over one century produced by two fuels-reduction treatments of thinning following by prescribed burning every one (Rx10) or two (Rx20) decades and for no treatment followed by intense wildfire once in the first 50 years (HF50) or once in the first 100 years (HF100). Our estimates include two uses of harvested wood, the current use as pallets, and multiproduct use as paper, pallets, and construction materials. Additionally, we included the economic value of damage and loss from wildfire. Results indicate that treatments increase carbon stock in live trees over time; however, the inclusion of carbon emissions from treatments reduces net carbon storage and thereby carbon credits and revenue. The economic valuation shows that the highest net benefit of $5029.74 ha−1 occurs for the Rx20 treatment with the HF50 baseline and the high estimated treatment benefits of avoided losses, regional economic benefits, and community value of fire risk reduction. The lowest net benefit of −$3458.02 ha−1 occurs for the Rx10 treatment with the HF100 baseline and the low estimated treatment benefits. We conclude that current nonmarket values such as avoided wildfire damage should be included with values of traditional wood products and emerging values of carbon storage to more appropriately estimate long-term benefits and costs of forest fuels-reduction treatments.

Liana Impacts on Carbon Cycling, Storage and Sequestration in Tropical Forests

AbstractMature tropical forests sequester large quantities of atmospheric CO2, which they store as plant biomass. These forests are changing however, including an increase in liana abundance and biomass over recent decades in Neotropical forests. We ask here how this increase in lianas might impact the tropical forest carbon cycle and their capacity for carbon storage and sequestration. Lianas reduce tree growth, survival, and leaf productivity; however, lianas also invest significantly in leaf production, and the increase in lianas could conceivably offset liana‐induced reductions in tree canopy productivity with no adverse effects to the forest‐level canopy productivity. By contrast, lianas decrease the total ecosystem uptake of carbon by reducing tree biomass productivity. Lianas themselves invest little in woody biomass, and store and sequester only a small proportion of the biomass in tropical forests. As lianas increase they may effectively displace trees, but the greater liana carbon stocks are unlikely to compensate for liana‐induced losses in net carbon sequestration and storage by trees. A potentially important additional consideration is the impact of lianas on the tree community. By competing more intensely with shade‐tolerant, more densely wooded trees than with fast‐growing, light‐wooded trees, lianas may shift tree composition toward faster‐growing species, which store relatively little carbon, and thereby further reduce the carbon storage capacity of tropical forests. Overall, current evidence indicates that the increase in lianas will negatively impact the carbon balance of tropical forests, with potentially far‐reaching consequences for global atmospheric CO2 levels and associated climate change.

Sensitivity of the oceanic carbon reservoir to tropical surface wind stress variations

The impact of variations of the Walker cell on the ocean carbon cycle is assessed using a coupled climate model. Idealized wind perturbations are investigated, with the trade winds increased/decreased by 10%, 20%, and 30%. A global‐mean reduction in oceanic carbon storage is found for increased equatorial easterlies, while moderately decreased trade winds give increased uptake. There is a nonlinear response to weakened tropical winds due to Pacific Ocean biological pump changes; with reduced nutrient upwelling resulting in decreased biological activity and remineralization in the deep ocean. This partially offsets the increased carbon uptake due to weaker trade winds. The overall change in net carbon storage reaches −26.2 PgC (12 ppm) in the 30% increase case and 4.2 PgC (−2 ppm) in the 20% decrease cases. Regional dissolved inorganic carbon (DIC) changes reach −3.3 mmol m−3 (2.1 mmol m−3) in the 10% decrease (increase) case. Gradually increasing wind perturbations give a similar pattern of DIC response to the full equilibrated solution.

Long-term warming restructures Arctic tundra without changing net soil carbon storage

High latitudes contain nearly half of global soil carbon, prompting interest in understanding how the Arctic terrestrial carbon balance will respond to rising temperatures. Low temperatures suppress the activity of soil biota, retarding decomposition and nitrogen release, which limits plant and microbial growth. Warming initially accelerates decomposition, increasing nitrogen availability, productivity and woody-plant dominance. However, these responses may be transitory, because coupled abiotic-biotic feedback loops that alter soil-temperature dynamics and change the structure and activity of soil communities, can develop. Here we report the results of a two-decade summer warming experiment in an Alaskan tundra ecosystem. Warming increased plant biomass and woody dominance, indirectly increased winter soil temperature, homogenized the soil trophic structure across horizons and suppressed surface-soil-decomposer activity, but did not change total soil carbon or nitrogen stocks, thereby increasing net ecosystem carbon storage. Notably, the strongest effects were in the mineral horizon, where warming increased decomposer activity and carbon stock: a 'biotic awakening' at depth.

Response of plant biomass and soil respiration to experimental warming and precipitation manipulation in a Northern Great Plains grassland

The interacting effects of altered temperature and precipitation are expected to have significant consequences for ecosystem net carbon storage. Here we report the results of an experiment that evaluated the effects of elevated temperature and altered precipitation, alone and in combination, on plant biomass production and soil respiration rates in a northern Great Plains grassland, near Lethbridge, Alberta Canada. Open-top chambers and rain shelters were used to establish an experiment in 2011 with two temperature treatments (warmed and control), each combined with three precipitation treatments (minus 50%, ambient (no manipulation), and plus 50%). A smaller experiment with only the two temperature treatments was conducted in 2012, a year with less rain than 2011. Our objectives were to determine the sensitivity of plant biomass production and soil respiration to temperature and moisture manipulations, and to test for direct and indirect effects of the environmental changes on soil respiration rates. The experimental manipulations resulted primarily in a significant increase in air temperature in the warmed treatment. There were no significant temperature or precipitation treatment effects on soil moisture content. Aboveground biomass was not significantly affected by the experimental manipulations, but the warmed plots of the ambient precipitation treatment showed an increase in root biomass relative to the control plots in 2011. The warmed treatment increased the cumulative loss of carbon in soil respiration (July–September) compared to the control by 497gCm−2 during 2011, and by 185gCm−2 during 2012. This higher soil respiration rate in both years was not directly caused by significant differences among treatments in soil temperature or soil moisture, but was likely an indirect result of increased carbon substrate availability in the warmed relative to the control treatment.

Effects of organic matter amendments on net primary productivity and greenhouse gas emissions in annual grasslands

Most of the world's grasslands are managed for livestock production. A critical component of the long-term sustainability and profitability of rangelands (e.g., grazed grassland ecosystems) is the maintenance of plant production. Amending grassland soils with organic waste has been proposed as a means to increase net primary productivity (NPP) and ecosystem carbon (C) storage, while mitigating greenhouse gas emissions from waste management. Few studies have evaluated the effects of amendments on the C balance and greenhouse gas dynamics of grasslands. We used field manipulations replicated within and across two rangelands (a valley grassland and a coastal grassland) to determine the effects of a single application of composted green waste amendments on NPP and greenhouse gas emissions over three years. Amendments elevated total soil respiration by 18% +/- 4% at both sites but had no effect on nitrous oxide or methane emissions. Carbon losses were significantly offset by greater and sustained plant production. Amendments stimulated both above- and belowground NPP by 2.1 +/- 0.8 Mg C/ha to 4.7 +/- 0.7 Mg C/ha (mean +/- SE) over the three-year study period. Net ecosystem C storage increased by 25-70% without including the direct addition of compost C. The estimated magnitude of net ecosystem C storage was sensitive to estimates of heterotrophic soil respiration but was greater than controls in five out of six fields that received amendments. The sixth plot was the only one that exhibited lower soil moisture than the control, suggesting an important role of water limitation in these seasonally dry ecosystems. Treatment effects persisted over the course of the study, which were likely derived from increased water-holding capacity in most plots, and slow-release fertilization from compost decomposition. We conclude that a single application of composted organic matter can significantly increase grassland C storage, and that effects of a single application are likely to carry over in time.

Nouvelles connaissances sur la dynamique globale de la biomasse après exploitation en forêt nord amazonienne

L'article présente les effets de l'exploitation forestière sur la dynamique de la biomasse aérienne à partir des résultats issus de l'exploitation commerciale au sein de deux forêts : Cikel dans l'Est du Pará au Brésil et Paracou en Guyane française. L'objectif principal a été de comparer l'impact de ce type d'exploitation sur la régénération de la biomasse aérienne dans ces deux forêts dont les caractéristiques sont différentes en termes de structure et de croissance. Dans les deux sites, l'intensité de l'exploitation s'avère être un facteur essentiel déterminant de la perte de biomasse et le temps nécessaire à sa régénération. À Paracou, la régénération de la biomasse aérienne perdue lors des coupes d'abattage de 10 arbres par hectare prendra 45 ans et plus de 100 ans en cas d'exploitation à plus forte intensité (21 arbres par hectare). À la Cikel, la biomasse aérienne se régénérera au bout de 49 ans après exploitation à raison de 6 arbres par hectare et au bout de 87 ans après prélèvement de 8 arbres par hectare. Cette régénération prendra donc autant de temps sur les deux sites, mais avec un moindre nombre d'arbres exploités à la Cikel, les arbres abattus étant de plus grande taille avec une biomasse aérienne individuelle plus importante qu'à Paracou. Après le passage en coupe, l'étude a établi une corrélation directe de la dynamique de la biomasse aérienne avec la structure initiale de la forêt ainsi qu'avec les paramètres de la dynamique forestière : mortalité, croissance et recrutement. L'accumulation de biomasse aérienne par la croissance globale des peuplements après coupe s'avère être un paramètre clé pour le stockage net du carbone, toutefois la contribution du recrutement ne devient significative à Paracou qu'au bout de 10 ans après exploitation. Il s'agit donc de favoriser la croissance des arbres résiduels après la coupe, grâce aux traitements sylvicoles tels que l'éclaircie sélective ou l'élimination de lianes. Alors que les deux forêts sont géographiquement assez proches, leurs capacités de régénération ne sont pas identiques et, en raison de la différence significative de taille des arbres, la forêt guyanaise pourrait tolérer une plus forte intensité d'exploitation.

Is biochar or straw-bale construction a better carbon storage from a life cycle perspective?

Biochar has been presented as a key technology for avoiding dangerous climate change. Pyrolysis converts part of the biomass feedstock into a gaseous fraction, which can be used for energy production. The remaining fraction is char, which is highly stable and resistant to biodegradation. When char is added to soil it increases carbon storage, reduces emissions and improves soil quality. Agricultural residues such as straw, stover and hulls are seen as the most accessible raw material. These residues could also be used as insulation in passive energy housing. Straw bale construction is a relatively simple technology, which has been applied for decades. It can store the carbon of the straw material into walls structures and in the process provides energy efficient housing. The climate benefits from improved energy efficiency depend on local conditions and energy production forms. In this study life cycle assessment was used to compare the climate impacts of biochar production and straw bale construction. On a life cycle perspective, straw bale construction results in higher net carbon storage than biochar production (3.3tCO2eq vs. 0.9tCO2eq/t of straw). However the result was found to be highly dependent on the assumptions on the overall energy efficiency of the replaced building stock.

Home-field advantage of litter decomposition and nitrogen release in forest ecosystems

Litter decomposition is a major fundamental ecological process that regulates nutrient cycling, thereby affecting net ecosystem carbon (C) storage as well as primary productivity in forest ecosystems. Litter decomposes in its home environment faster than in any other environment. However, evidence for this phenomenon, which is called the home-field advantage (HFA), has not been universal. We provide the first HFA quantification of litter decomposition and nutrient release through meta-analysis of published data in global forest ecosystems. Litter mass loss was 4.2 % faster on average, whereas nitrogen (N) release was 1.7 % lower at the home environment than in another environment. However, no HFA of phosphorus (P) release was observed. Broadleaf litter (4.4 %) had a higher litter mass loss HFA than coniferous litter (1.0 %). The positive HFA of N release was found in the coniferous litter. Mass loss HFA was significantly and negatively correlated with the initial lignin:N litter ratio. The litter decomposition and N release HFAs were obtained when mesh size ranged from 0.15 mm to 2.0 mm. The HFA of litter decomposition increased with decomposition duration during the early decomposition stage. The HFA of N release was well correlated with mass loss, and the greatest HFA was at mass loss less than 20 %. Our results suggest that the litter decomposition and N release HFAs are widespread in forest ecosystems. Furthermore, soil mesofauna is significantly involved in the HFA of litter decomposition.

Carbon sequestration potential of post-mining reforestation activities on the KwaZulu-Natal coast, South Africa

Restoration of former mined land can potentially capture large quantities of atmospheric carbon dioxide if appropriate reclamation techniques and post-reclamation management strategies are applied. The objectives of the current study were: to quantify carbon stocks in five pools; to develop empirical relationships between stand age and carbon stocks; to compare the carbon sequestration potential of rehabilitated land under different land uses and to recommend management practices to maximize carbon sequestration. The carbon stocks in five pools (aboveground, belowground, litter, debris and soil), of the rehabilitated vegetation were quantified. For this purpose, 18 sites were selected including both commercial plantations and rehabilitated indigenous forests. The relationship between total, aboveground and belowground carbon stocks in the Casuarina equisetifolia plantation and stand age was sigmoidal, whereas the relationship was linear for the rehabilitating indigenous forest. The rehabilitated indigenous forest exceeded the mean net carbon storage of C. equisetifolia plantations after �19 years. Maximum carbon accumulation in the rehabilitated indigenous forest compared well with values reported for reclaimed ecosystems in the USA and Europe. Carbon sequestration potential of the mined land could be optimized and natural capital restored through reforestation of harvested C. equisetifolia plantations with indigenous forest.

Carbon storage, timber production, and biodiversity: comparing ecosystem services with multi‐criteria decision analysis

Increasingly, land managers seek ways to manage forests for multiple ecosystem services and functions, yet considerable challenges exist in comparing disparate services and balancing trade-offs among them. We applied multi-criteria decision analysis (MCDA) and forest simulation models to simultaneously consider three objectives: (1) storing carbon, (2) producing timber and wood products, and (3) sustaining biodiversity. We used the Forest Vegetation Simulator (FVS) applied to 42 northern hardwood sites to simulate forest development over 100 years and to estimate carbon storage and timber production. We estimated biodiversity implications with occupancy models for 51 terrestrial bird species that were linked to FVS outputs. We simulated four alternative management prescriptions that spanned a range of harvesting intensities and forest structure retention. We found that silvicultural approaches emphasizing less frequent harvesting and greater structural retention could be expected to achieve the greatest net carbon storage but also produce less timber. More intensive prescriptions would enhance biodiversity because positive responses of early successional species exceeded negative responses of late successional species within the heavily forested study area. The combinations of weights assigned to objectives had a large influence on which prescriptions were scored as optimal. Overall, we found that a diversity of silvicultural approaches is likely to be preferable to any single approach, emphasizing the need for landscape-scale management to provide a full range of ecosystem goods and services. Our analytical framework that combined MCDA with forest simulation modeling was a powerful tool in understanding trade-offs among management objectives and how they can be simultaneously accommodated.

China's crop productivity and soil carbon storage as influenced by multifactor global change

Much concern has been raised about how multifactor global change has affected food security and carbon sequestration capacity in China. By using a process-based ecosystem model, the Dynamic Land Ecosystem Model (DLEM), in conjunction with the newly developed driving information on multiple environmental factors (climate, atmospheric CO2 , tropospheric ozone, nitrogen deposition, and land cover/land use change), we quantified spatial and temporal patterns of net primary production (NPP) and soil organic carbon storage (SOC) across China's croplands during 1980-2005 and investigated the underlying mechanisms. Simulated results showed that both crop NPP and SOC increased from 1980 to 2005, and the highest annual NPP occurred in the Southeast (SE) region (0.32 Pg C yr(-1) , 35.4% of the total NPP) whereas the largest annual SOC (2.29 Pg C yr(-1) , 35.4% of the total SOC) was found in the Northeast (NE) region. Land management practices, particularly nitrogen fertilizer application, appear to be the most important factor in stimulating increase in NPP and SOC. However, tropospheric ozone pollution and climate change led to NPP reduction and SOC loss. Our results suggest that China's crop productivity and soil carbon storage could be enhanced through minimizing tropospheric ozone pollution and improving nitrogen fertilizer use efficiency.

시공간 정보기반 산림 생태계의 기후변화 취약성 평가

The purpose of this study was to assess the vulnerability of forest ecosystem to climate change in South Korea using socio-environmental indicators and the results of two vegetation models named as Hydrological and Thermal Analogy Group(HyTAG), and MAPSS-Century 1(MC1). The changing frequency and direction of biome types estimated by HyTAG model was used for quantifying sensitivity and adaptive capacity of forest distribution. Similarly, the variation and changing tendency of net primary production and soil carbon storage estimated by MC1 model was used for quantifying sensitivity and adaptive capacity of forest function. As socio-environmental indicators, many statistical data such as financial autonomy rate and the number of forestry officer was prepared. All indicators were standardized, and then calculated using the vulnerability assessment equation. The period of vulnerability assessment was divided into the past(1971-2000) and the future(2021-2050). To understand what policy has a priority to climate change, distribution maps of each indicators was depicted and the vulnerability results were compared among administrative districts. Evident differences could be found in entire study area. These differences were mostly derived from regionalspecific adaptive capacity. The result and methodology of this study would be helpful for the development of decision-making supporting system and policy making in forest management with respect to climate change.

南亚热带米老排人工林碳贮量及其分配特征

Measurements of carbon stock and carbon distribution of Mytilaria laosensis plantation are useful for assessing its carbon sink capacity and developing appropriate multi-purpose forest management model in subtropical area.In this paper,the concentration,storage and allocation of carbon for the Mytilaria laosensis plantation were investigated through biomass harvesting.Two dominant,three intermediate and two suppressed trees were destructively sampled.Stems were cut at the soil surface.Total tree height(from ground to the terminal bud,H),length of live crown,diameter at breast height(DBH),diameter at the base of live crown were measured and recorded immediately.The live crown was marked as three sections(top,middle and bottom),and all new leaves,old leaves,new branches,old branches from each canopy position were cut and weighted separately.Stem were cut into 2 m sections and weighted.At the end of each stem section,a 5cm thick disk was cut,weighted and taken into lab for moisture content determination.The root system were divided into stump,coarse root and fine root(5mm in diameter) and weighted at the field.From each component approximately 500—1000g of fresh mass were randomly sampled and placed in a labeled bag for moisture content determination.Three standard plots were sampled in the 20-year-old Mytilaria laosensis plantation and three 1 m×1 m subplots were sampled along the diagonal.The litter layer was divided into fresh layer and humus layer.The fresh mass of the litter layer in the three 1m×1m subplots were determined,and about 500—1000g were taken into lab for moisture and carbon content determination.Three soil sampling profiles were set in each standard plot.The soil profile were divided into six layers: 0—10cm,10—20cm,20—40cm,40—60cm,60—80cm and 80—100cm.Soil bulk density were measured and the soil samples(500—1000g) in each soil profile were sampled and mixed into one sample for soil moisture and carbon concentration determination for each plot.The results showed that carbon concentration in different organs of Mytilaria laosensis ranged from 51.73% to 55.75%,which in the order as follows: new foliagenew branchold foliagestemolder branchstumpcoarse rootfine root.The carbon concentration of the fresh litter layer was higher compared to the decomposing litter layer.Carbon concentration in the 0—100cm soil decreased with the increasing of soil depth from 4.10% to 0.62%.The total carbon storage in the 20-year-old Mytilaria laosensis plantation was 331.61 t/hm2.The carbon stocks of tree,litter,and soil layer were 154.07,2.74,and 174.80 t/hm2,respectively.The annual net carbon storage of the Mytilaria laosensis plantation was 14.77 t/hm2,which equals to a mitigation of 54.16t CO2,where the tree,litter,and soil layer accounted for 60.73%,6.16%,and 33.11%,respectively.