Maximize Carbon Sequestration Research Articles

Future carbon sequestration potential in a widespread transcontinental boreal tree species: Standing genetic variation matters!

Climate change (CC) necessitates reforestation/afforestation programs to mitigate its impacts and maximize carbon sequestration. But comprehending how tree growth, a proxy for fitness and resilience, responds to CC is critical to maximize these programs' effectiveness. Variability in tree response to CC across populations can notably be influenced by the standing genetic variation encompassing both neutral and adaptive genetic diversity. Here, a framework is proposed to assess tree growth potential at the population scale while accounting for standing genetic variation. We applied this framework to black spruce (BS, Picea mariana [Mill] B.S.P.), with the objectives to (1) determine the key climate variables having impacted BS growth response from 1974 to 2019, (2) examine the relative roles of local adaptation and the phylogeographic structure in this response, and (3) project BS growth under two Shared Socioeconomic Pathways while taking standing genetic variation into account. We modeled growth using a machine learning algorithm trained with dendroecological and genetic data obtained from over 2600 trees (62 populations divided in three genetic clusters) in four 48-year-old common gardens, and simulated growth until year 2100 at the common garden locations. Our study revealed that high summer and autumn temperatures negatively impacted BS growth. As a consequence of warming, this species is projected to experience a decline in growth by the end of the century, suggesting maladaptation to anticipated CC and a potential threat to its carbon sequestration capacity. This being said, we observed a clear difference in response to CC within and among genetic clusters, with the western cluster being more impacted than the central and eastern clusters. Our results show that intraspecific genetic variation, notably associated with the phylogeographic structure, must be considered when estimating the response of widespread species to CC.

Ecosystem services of irrigated and controlled drainage agricultural systems: A contemporary global perspective

AbstractIrrigated agriculture provides 40% of the world's crop‐based foods but often with a negative impact on the environment. It is important to recognize that in addition to providing food and fibre, irrigation and controlled drainage systems can be optimized to provide additional ecosystem services and mitigate climate change by using resources in a more efficient way. Contemporary case studies were identified from around the world, including flood control by paddy fields in Japan, water quality enhancement and wastewater reuse in South Africa and Taiwan, micro‐/meso‐climate regulation in Ethiopia and Japan, controlled drainage and sub‐irrigation to maximize carbon sequestration and minimize leaching in Finland, and groundwater table management to reduce irrigation water and pumping requirements in Turkey. Irrigation infrastructure, such as rice paddy terraced landscapes (Japan) and large dams and canals (Australia), have also achieved notable additional ecotourism job creation. Case studies were analysed in terms of funding opportunities and compared using the Common International Classification of Ecosystem Services system. It is recommended that planning frameworks be developed that seek to optimize ecosystem services such as the ones discussed above. Policy should be updated to recognize these services and provide incentives to irrigators and water management entities accordingly.

Elevation Changes in Restored Marshes at Poplar Island, Chesapeake Bay, MD: II. Modeling the Importance of Marsh Development Time

AbstractTidal marshes in the Chesapeake Bay are vulnerable to the accelerating rate of sea-level rise (SLR) and subsidence. Restored and created marshes face the same risks as natural marshes, and their resilience to SLR may depend upon appropriate design and implementation. Here, the Coastal Wetland Equilibrium Model (CWEM) was used to assess the resilience of tidal marshes at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island (PI) in mid-Chesapeake Bay, MD, where dredged material from navigation channels is being used to create new tidal marshes planted with Spartina alterniflora in the low marsh and S. patens in the high marsh. The site is microtidal with low inorganic sediment inputs, where the rate of marsh elevation change is dominated by the production of organic matter and, therefore, is proportional to net ecosystem production (NEP). The model demonstrated the importance of marsh development for surface elevation gain. In created marshes, the buildout of belowground biomass adds volume and results in faster growth of marsh elevation, but the gains slow as the marsh matures. Elevation gain is the lessor of the recalcitrant fraction of NEP sequestered in sediment or the rate of increase in accommodation space. Marshes can keep up with and fill accommodation space with sequestered NEP up to a tipping point determined by the rate of SLR. The PI low marsh platform was forecasted to drown in about 43 years after construction at the current rate of SLR. Marsh loss can be mitigated by periodic thin layer placement (TLP) of sediment. CWEM was used to simulate PI marsh responses to different TLP strategies and showed that there is an optimal design that will maximize carbon sequestration and resilience depending on the trajectory of mean sea level.

Maximizing carbon sequestration potential in Chinese forests through optimal management

Forest carbon sequestration capacity in China remains uncertain due to underrepresented tree demographic dynamics and overlooked of harvest impacts. In this study, we employ a process-based biogeochemical model to make projections by using national forest inventories, covering approximately 415,000 permanent plots, revealing an expansion in biomass carbon stock by 13.6 ± 1.5 Pg C from 2020 to 2100, with additional sink through augmentation of wood product pool (0.6-2.0 Pg C) and spatiotemporal optimization of forest management (2.3 ± 0.03 Pg C). We find that statistical model might cause large bias in long-term projection due to underrepresentation or neglect of wood harvest and forest demographic changes. Remarkably, disregarding the repercussions of harvesting on forest age can result in a premature shift in the timing of the carbon sink peak by 1–3 decades. Our findings emphasize the pressing necessity for the swift implementation of optimal forest management strategies for carbon sequestration enhancement.

Carbon stock projection for four major forest plantation species in Japan

Carbon sequestration via afforestation and forest growth is effective for mitigating global warming. Accurate and robust information on forest growth characteristics by tree species, region, and large-scale land-use change is vital and future prediction of forest carbon stocks based on this information is of great significance. These predictions allow exploring forestry practices that maximize carbon sequestration by forests, including wood production. Forest inventories based on field measurements are considered the most accurate method for estimating forest carbon stocks. Japan's national forest inventories (NFIs) provide stand volumes for all Japanese forests, and estimates from direct field observations (m-NFIs) are the most reliable. Therefore, using the m-NFI from 2009 to 2013, we selected four major forest plantation species in Japan: Cryptomeria japonica, Chamaecyparis obtusa, Pinus spp., and Larix kaempferi and presented their forest age–carbon density function. We then estimated changes in forest carbon stocks from the past to the present using the functions. Next, we investigated the differences in the carbon sequestration potential of forests, including wood production, between five forestry practice scenarios with varying harvesting and afforestation rates, until 2061. Our results indicate that, for all four forest types, the estimates of growth rates and past forest carbon stocks in this study were higher than those considered until now. The predicted carbon sequestration from 2011 to 2061, assuming that 100 % of harvested carbon is retained for a long time, twice the rate of harvesting compared to the current rate, and a 100 % afforestation rate in harvested area, was three to four times higher than that in a scenario with no harvesting or replanting. Our results suggest that planted Japanese forests can exhibit a high carbon sequestration potential under the premise of active management, harvesting, afforestation, and prolonging the residence time of stored carbon in wood products with technology development.

Effects of plant community structural characteristics on carbon sequestration in urban green spaces

The structural characteristics of plant communities in urban green spaces have a significant impact on their carbon sequestration function. In this study, comprehensive data were collected from 106 plant communities (each 20 m × 20 m) in Zhengzhou Green Expo Park. We assessed aboveground and soil carbon storage, alongside maintenance carbon emissions, to quantify carbon dynamics. Our primary objective was to establish a statistical model that correlates the structural attributes of plant communities with their total annual carbon sequestration. This model aims to provide a quantitative framework for optimizing community structures to maximize carbon sequestration in urban green spaces. The results showed that density and coverage were significantly and positively correlated with aboveground and soil carbon stocks. Density and mean height were significantly and positively correlated with maintenance carbon emissions. Density played a key structural role in regulating the total carbon sequestration of the plant communities, being 27.24 times more effective than coverage. The total annual carbon sequestration of the plant community reached an optimal value of 327.67 kg CO2-eq/y−1 at a density and cover of 0.15 and 1, respectively. This study provides valuable data for increasing the carbon sink ability of urban green spaces through plant structure regulation and supporting low-carbon development strategies in urban management.

Predicting biochar properties and pyrolysis life-cycle inventories with compositional modeling

Biochar, formed through slow pyrolysis of biomass, has garnered attention as a pathway to bind atmospheric carbon in products. However, life cycle assessment data for biomass pyrolysis have limitations in data quality, particularly for novel processes. Here, a compositional, predictive model of slow pyrolysis is developed, with a focus on CO2 fluxes and energy products, reflecting mass-weighted cellulose, hemicellulose, and lignin pyrolysis products for a given pyrolysis temperature. This model accurately predicts biochar yields and composition within 5 % of experimental values but shows broader distributions for bio-oil and syngas (typically within 20 %). This model is demonstrated on common feedstocks to quantify biochar yield, energy, and CO2 emissions as a function of temperature and produce key life cycle inventory flows (e.g., 0.73 kg CO2/kg poplar biochar bound carbon at 500 °C). This model can be adapted to any lignocellulosic biomass to inform development of pyrolysis processes that maximize carbon sequestration.

Evaluation of microalgae biodiesel for carbon neutrality based on the waste treatment by the autotrophic and heterotrophic combination

Microalgae aid in addressing environmental pollution and climate change by enabling carbon sequestration as part of CCUS, which offers a promising solution to reduce fossil fuel dependence and mitigate emissions. This study uses the combination of autotrophic and heterotrophic methods to enhance the benefits of biodiesel based on waste treatment. The study demonstrates that by integrating autotrophic and heterotrophic biodiesel production, it is feasible to attain substantial economic advantages while maximizing carbon sequestration and reducing emissions. It shows a 62.73 % cost reduction for 1 ton of biodiesel produced using the coupled heterotrophic method over traditional photobioreactors. Additionally, compared with the corresponding heterotrophic proliferation, the carbon emissions of biodiesel under autotrophic coupled heterotrophic proliferation were reduced by 21.16 % and 24.08 %, respectively. The total economic benefits of biodiesel under autotrophic coupled heterotrophic proliferation increased by 2.12 % and 3.10 % compared to heterotrophic proliferation. However, it should be noted that due to the high carbon emissions caused by the heterotrophic proliferation of microalgae, biodiesel does not achieve negative carbon emissions. This study provides a new development strategy for waste resource utilization and microalgae bioenergy production phase. It will provide a theoretical and practical framework for utilizing microalgae biodiesel to achieve worldwide carbon neutrality.

Rewetting increases vegetation cover and net growing season carbon uptake under fen conditions after peat-extraction in Manitoba, Canada

The moss layer transfer technique has been developed to restore the carbon sequestration function and typical vegetation of Sphagnum-dominated peatlands after peat extraction in North America. However, the technique does not lead to successful bryophyte establishment when applied to peatlands with a richer residual fen peat. Therefore, we evaluated an alternative method of active rewetting and passive vegetation establishment using vegetation surveys and carbon dioxide and methane (CH4) flux measurements at a post-extracted fen in southern Manitoba, Canada. After one growing season post-rewetting, wetland vegetation established and the site was a net carbon sink over the growing season. However, high abundance of Carex lasiocarpa 10 years post-treatment led to higher CH4 emissions than the reference ecosystem. Successful establishment of wetland vegetation is attributed to the area being surrounded by undisturbed fens that can provide a local source of plant propagules. Bryophyte expansion was less successful than vascular plants, likely due to episodic flooding and shading from the sedge communities. Therefore, careful management of water levels to just below the peat surface is needed if reference vegetation community recovery is the goal of restoration. Water level management will also play a key role in controlling CH4 emissions to maximize carbon sequestration potential.

Optimizing Carbon Sequestration in Forest Management Plans Using Advanced Algorithms: A Case Study of Greater Khingan Mountains

The Paris Agreement aims to combat climate change by reducing greenhouse gas emissions, with bioenergy identified as a potential solution. However, concerns remain about its impact on carbon stocks and the optimal timing for implementation. To address these challenges, we propose a comprehensive multi-objective optimization model for forest management that maximizes carbon sequestration and economic benefits. Our model integrates three key components: (1) a sophisticated carbon-sequestration model encompassing living plants, wood forest products, and soil and microbial carbon uptake, (2) dynamic factors such as forest fires and extreme weather events, and (3) an economic benefits model focused on wood-processing products. We optimized the forest-management strategy over ten years by leveraging the simulated annealing and Karush–Kuhn–Tucker (KKT) algorithms. Through simulations using data from China’s Greater Khingan Mountains region, we explored the optimal logging plans for maximizing carbon sequestration without external factors. Our results revealed that the optimized logging plans significantly enhance carbon sequestration compared to proportionally averaged logging plans. Next, we investigated the impact of external factors on forest management, specifically wildfires and extreme weather events. Our findings demonstrate that wildfires have a more-substantial detrimental effect on the absolute value of carbon sequestration and the extent of improvement achieved through model optimization. At the same time, extreme cold primarily affects the growth rate of carbon sequestration. We employed a linear-weighting approach and the Analytic Hierarchy Process (AHP) to address the trade-offs between carbon sequestration and economic benefits to transform the multi-objective optimization function into a single objective. The results showed that the optimized harvesting schedule can lead to improved economic benefits compared to uniformly harvesting trees. Moreover, the joint optimization approach enabled us to identify optimal solutions that balance carbon sequestration and economic benefits, offering sustainable forest management strategies. Our study provides valuable quantitative insights into forest management strategies that balance carbon sequestration and economic benefits, making it highly relevant for real-world applications.

Carbon dioxide emissions in relation to water table in a restored fen

AbstractMany peatlands have been drained for anthropogenic purposes, and there is high interest in restoring them for their carbon storage ability and critical habitat. Peatlands hold a disproportionate amount of global soil carbon, making peatland restoration a promising approach for mitigating carbon emissions. In this study, site factors were investigated that affect peat carbon dioxide flux at Cold Spring fen in Minnesota, which is undergoing restoration. Peat carbon dioxide flux and water table depth were monitored throughout the growing season at two locations previously disturbed to different degrees by row‐crop agriculture. Flux ranged from 0.55 to 12.71 µmol m−2 s−1 and was highest during peak growing season. Lower flux corresponded to elevated water table conditions. The more disturbed location often had lower flux, indicating success in hydrological restoration. The water table is an important factor in peatland restoration, and water table management should be considered to maximize carbon sequestration.

Identifying Optimal Forest Management Maximizing Carbon Sequestration in Mountain Forests Impacted by Natural Disturbances: A Case Study in the Alps

The role of forests in mitigating climate change by acting as a carbon sink is becoming increasingly important. Forest management practices can either positively or negatively affect the ability of forests to mitigate climate change. The objectives of our study were to: (a) investigate the effects of natural disturbances on long-term carbon sequestration dynamics in forests and (b) identify opportunities to adapt current forest management practices to increase carbon sequestration in forests. The study focused on mixed mountain forests in the Slovenian Alps, dominated by Norway spruce, and used the SLOMATRIX model to simulate forest development. Three forest management scenarios were simulated: (1) no management, (2) business-as-usual and (3) an optimized scenario maximizing carbon sequestration in forests while achieving the required harvest. Our results indicate that both forest management practices and natural disturbances have an impact on carbon sequestration dynamics. Optimizing harvests resulted in changes in the diameter structure and species composition of the harvested trees. Although natural disturbances can hinder the mitigation of climate change impacts, they can also catalyze forest adaptation to climate change and reduce the time required to reach carbon equilibrium.

Controls on organic carbon stocks among restored wetland soils in the Long Point region of southern Ontario, Canada

Freshwater marsh restoration can be a viable natural climate solution; however, the extent to which marsh soils bury and preserve organic carbon within policy‐relevant timescales remains highly uncertain. Here, we compare organic carbon masses and accumulation rates from an undrained reference marsh, a passively restored freshwater marsh (reflooded after 1954) and a chronosequence of actively restored freshwater marshes (<10 years in age) situated in Lake Erie watersheds in the Long Point Biosphere Reserve of Ontario, Canada. The reference site has sustained the highest rates of short‐term organic carbon accumulation (235 g C m−2 yr−1) over the last four decades and has the highest mass of soil organic carbon (122 tC/ha) at 0–30 cm depth. Organic carbon masses are highly variable among all restored wetlands (16–115 tC/ha) at 0–30 cm depth and are not strongly related to time since restoration at least over the last 10 years. Nonetheless, we show that passive wetland restoration generates high rates of organic carbon accumulation (144 g m−2 yr−1) on a multidecadal scale where sites are low‐lying, underlain by alluvial deposits and connected to larger ground and surface water networks. Active restoration measures (e.g. excavation, installation of berms) may promote organic carbon preservation, particularly where fine‐grained soil texture promotes waterlogging. We demonstrate the importance of substrate, topographic gradient, and hydrology in selecting sites for marsh restoration to maximize carbon sequestration, and argue that the presettlement context and reference paleorecords provide necessary baselines for directing successful wetland restoration.

Differences in ecosystem organic carbon stocks due to species selection and site elevation of restored mangrove forests

Mangrove forests are important blue carbon ecosystems. Site elevation and species selection are very important for successful restoration of mangrove forests. It is vital for calculating carbon sequestration of mangrove forests to know the combined influences of species selection and site elevation on the ecosystem organic carbon stock (EOCS). In this study, the combined effects of site elevation (above or below local mean sea level) and species selection (Kandelia obovata vs Avicennia marina) on the EOCS including vegetation organic carbon stock (VOCS) and soil organic carbon stock (SOCS) were quantified through an in situ planting experiment. The total vegetation biomass decreased approximately 48.79% in the K. obovata forest and 19.71% in the A. marina forest because of changes in each component (leaf, stem, branch and root) biomass with the decreases in site elevation. Due to changes in SOCS and VOCS with the decreases in site elevation, EOCS of the A. marina forest decreased approximately 12.3% and EOCS of the K. obovata forest decreased approximately 40.3%. At the site below local mean sea level, the A. marina forest had higher EOCS than the K. obovata forest. These indicated that in order to maximize carbon sequestration in restored mangrove forests, A. marina should be selected for the projects with site elevation below local mean sea level, while K. obovata should be selected for those with site elevation above local mean sea level.

Assessing the co-benefits of urban greening coupled with rainwater harvesting management under current and future climates across USA cities

Globally, urban areas face multiple challenges owing to climate change. Urban greening (UG) is an excellent option for mitigating flood risk and excess urban heat. Rainwater harvesting (RWH) systems can cope with plant irrigation needs and urban water management. In this study, we investigated how UG and RWH work together to mitigate environmental risks. By incorporating a new RWH module into the urban ecohydrological model Urban Tethys-Chloris (UT&C), we tested different uses of intervention approaches for 28 cities in the USA, spanning a variety of climates, population densities, and urban landscapes. UT&C was forced by the latest generation convection-permitting climate model simulations of the current (2001–2011) and end-of-century (RCP8.5) climate. Our results showed that neither UG nor RWH, through the irrigation of vegetation, could significantly contribute to mitigating the expected strong increase in 2 m urban canyon temperatures under a high-emission scenario. RWH alone can sufficiently offset the intensifying surface flood risk, effectively enhance water saving, and support UG to sustain a strong urban carbon sink, especially in dry regions. However, in these regions, RWH cannot fully fulfill plant water needs, and additional measures to meet irrigation demand are required to maximize carbon sequestration by urban vegetation.

Improving a Process-Based Model to Simulate Forest Carbon Allocation under Varied Stand Density

Carbon allocation is an important mechanism through which plants respond to environmental changes. To enhance our understanding of maximizing carbon uptake by controlling planting densities, the carbon allocation module of a process-based model, TRIPLEX-Management, was modified and improved by introducing light, soil water, and soil nitrogen availability factors to quantify the allocation coefficients for different plant organs. The modified TRIPLEX-Management model simulation results were verified against observations from northern Jiangsu Province, China, and then the model was used to simulate dynamic changes in forest carbon under six density scenarios (200, 400, 600, 800, 1000, and 1200 stems ha−1). The mean absolute errors between the predicted and observed variables of the mean diameter at breast height, mean height, and estimated aboveground biomass ranged from 15.0% to 26.6%, and were lower compared with the original model simulated results, which ranged from 24.4% to 60.5%. The normalized root mean square errors ranged from 0.2 to 0.3, and were lower compared with the original model simulated results, which ranged from 0.3 to 0.6. The Willmott index between the predicted and observed variables also varied from 0.5 to 0.8, indicating that the modified TRIPLEX-Management model could accurately simulate the dynamic changes in poplar (Populus spp.) plantations with different densities in northern Jiangsu Province. The density scenario results showed that the leaf and fine root allocation coefficients decreased with the increase in stand density, while the stem allocation increased. Overall, our study showed that the optimum stand density (approximately 400 stems ha−1) could reach the highest aboveground biomass for poplar stands and soil organic carbon storage, leading to higher ecological functions related to carbon sequestration without sacrificing wood production in an economical way in northern Jiangsu Province. Therefore, reasonable density control with different soil and climate conditions should be recommended to maximize carbon sequestration.

Dissolved Iron from Steel Slag with Its Chelating Agent Promotes Seaweed Growth

Blue carbon ecosystems are crucial for carbon sequestration on a global scale. However, it is unclear how we could promote and maximize carbon sequestration. Here, we demonstrate that providing an iron source to seaweed fostered its growth through increased photosynthetic efficiency and transformed the carbon into a biomass. Firstly, we revealed that the mixture of the steel slag and DTPA eluted iron dramatically in seawater. Next, we applied the eluate of the slag-DTPA pellet to the seaweed. The results for the eluate treatment showed a 25.8% increase in the photosynthetic pigment level and a 44.9% increase in the seaweed weight. Furthermore, we confirmed no elution of potential toxic substances from the steel slag and DTPA pellet. Finally, we applied the pellet at a depth of 15 m near seaweeds and observed a 52.0% increase of carbon weight in the pellet treated group, while the non-treated group showed only a 10.3% increase for five months. This study indicated that steel slag-DTPA pellet treatment induced seaweed growth and efficiently transformed its carbon into a seaweed biomass. Thus, steel slag and its chelating agent may contribute to the promotion of sea forestation and a subsequent increase in carbon sequestration known as blue carbon.

Potential for Return on Investment in Rehabilitation-Oriented Blue Carbon Projects: Accounting Methodologies and Project Strategies

Opportunities to boost climate change mitigation and adaptation (CCMA) and sustainable conservation financing may lie in enhancing blue carbon sequestration, particularly in developing nations where coastal ecosystems are extensive and international carbon markets offer comparatively attractive payments for environmental stewardship. While blue carbon is receiving increased global attention, few credit-generating projects are operational, due to low credit-buyer incentives with uncertainty in creditable emissions reductions and high project costs. Little empirical guidance exists for practitioners to quantify return-on-investment (ROI) and viability of potential projects, particularly for rehabilitation where multiple implementation options exist with diverse associated costs. We map and model drivers of mangrove natural regeneration (NR) using remote sensing (high-resolution satellite imagery segmentation and time-series modeling), and subsequent carbon sequestration using field- and literature-derived data, across abandoned aquaculture ponds in the Philippines. Using project-specific cost data, we then assess ROI for a hypothetical rehabilitation-focused mangrove blue carbon project at a 9.68 ha abandoned pond over a 10-year timeframe, under varied rehabilitation scenarios [NR vs. assisted natural regeneration (ANR) with planting], potential emissions reduction accreditation methodologies, carbon prices and discount rates. NR was faster in lower-lying ponds with lower tidal exposure (greater pond dike retention). Forecasted carbon sequestration was 3.7- to 5.2-fold and areal “greenbelt” regeneration 2.5- to 3.4-fold greater in our case study under ANR than NR. Variability in modeled sequestration rates drove high uncertainty and credit deductions in NR strategies. ROI with biomass-only accreditation was low and negative under NR and ANR, respectively. ROI was greater under ANR with inclusion of biomass and autochthonous soil carbon; however, neither strategy was highly profitable at current voluntary market carbon prices. ANR was the only scenario that fulfilled coastal protection greenbelt potential, with full mangrove cover within 10 years. Our findings highlight the benefits of ANR and soils inclusion in rehabilitation-oriented blue carbon projects, to maximize carbon sequestration and greenbelt enhancement (thus enhance pricing with potential bundled credits), and minimize forecasting uncertainty and credit-buyers’ perceived risk. An ANR rehabilitation strategy in low-lying, sea-facing abandoned ponds with low biophysical intervention costs may represent large blue carbon CCMA opportunities in regions with high aquaculture abandonment.

Carbon content and allometric models to estimate aboveground biomass for forest areas under restoration

Maximizing carbon sequestration is crucial to mitigate climate change and indicates that the restoration technique used was effective. To quantify carbon stock over time on areas being restored, suitable allometric equations are needed. These equations are lacking for the Atlantic forest, lacking even more for restoration sites, and rare for restoration areas implemented with the active method, technique often used to restore Atlantic forest areas. Thus, the objective of this study was 3‐fold. First, to provide an equation to estimate aboveground biomass for 5‐year‐old Atlantic forest under restoration implemented with the active method. Second, to determine carbon content for the branch, stem, and foliage pools for those areas. Third, to present biomass, carbon content, and carbon stock benchmarks for 5‐year‐old areas under restoration implemented with the active method. Three sites were sampled with nine plots each, measuring tree height and diameter. One subplot was established in each plot, and all trees within it were harvested and had fresh weight measured and samples were taken to the laboratory to dry weight and carbon content determination. Ten models estimating biomass were fitted and tested. Mean carbon content in foliage, branch, stem, and the weighted average were 44.8, 44.5, 45.8, and 45.3%, respectively. Mean biomass and carbon stock were 20.19 ± 0.146 Mg/ha and 9.73 Mg C/ha. We concluded that the equation that we provide is precise, and very necessary to estimate biomass for young restoration areas at the Atlantic forest.

Carbon versus Timber Economy in Mediterranean Forests

Forests produce goods and services, but the forest economy is based on goods, with market price, more than on services. Under Mediterranean climate conditions forests have low timber production, being frequently financially loss-making, despite the environmental services provided, such as carbon sequestration. Timber production and carbon sequestration are compatible, and a proper valuation of both can allow for a more balanced management. The aim of this paper is to assess financially a scenario based on maximizing carbon sequestration versus another based on maximizing timber harvesting in a Mediterranean forest. To do that, timber stock, growth and harvesting, and carbon sequestration have been calculated. Applying market prices for timber and CO2 both scenarios have been assessed, carrying out a sensitivity analysis. Maximising carbon sequestration was more profitable in the vast majority of combinations; timber harvesting was only more profitable if CO2 prices fell below 30% and timber price increases more than 20%; timber price rise is possible, but a collapse in CO2 price is not probable. The real barrier is that while timber is as a commodity with market price, carbon sequestration is not. The challenge for the future is to pay for carbon sequestration, mobilising resources from polluting sectors to forests.