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Large-scale reforestation, afforestation, and forest restoration schemes have gained global support as climate change mitigation strategies due to their significant carbon dioxide removal (CDR) potential. However, there has been limited research into the unintended consequences of forestation from a biophysical perspective. In the Community Earth System Model version 2 (CESM2), we apply a global forestation scenario, within a Paris Agreement-compatible warming scenario, to investigate the land surface and hydroclimate response. Compared to a control scenario where land use is fixed to present-day levels, the forestation scenario is up to 2 °C cooler at low latitudes by 2100, driven by a 10 % increase in evaporative cooling in forested areas. However, afforested areas where grassland or shrubland are replaced lead to a doubling of plant water demand in some tropical regions, causing significant decreases in soil moisture (∼ 5 % globally, 5 %–10 % regionally) and water availability (∼ 10 % globally, 10 %–15 % regionally) in regions with increased forest cover. While there are some increases in low cloud and seasonal precipitation over the expanded tropical forests, with enhanced negative cloud radiative forcing, the impacts on large-scale precipitation and atmospheric circulation are limited. This contrasts with the precipitation response to simulated large-scale deforestation found in previous studies. The forestation scenario demonstrates local cooling benefits without major disruption to global hydrodynamics beyond those already projected to result from climate change, in addition to the cooling associated with CDR. However, the water demands of extensive forestation, especially afforestation, have implications for its viability, given the uncertainty in future precipitation changes. [ABSTRACT FROM AUTHOR]

Afforestation is an important way to effectively reduce carbon emissions from human activities and increase carbon sinks in forest ecosystems. It also plays an important role in climate change mitigation. Currently, few studies have examined the spatiotemporal dynamics of future afforestation areas, which are crucial for assessing future carbon sequestration in forest ecosystems. In order to obtain the dynamic distribution of potential afforestation land over time under future climate change scenarios in China, we utilized the random forest method in this study to calculate weights for the selected influencing factors on potential afforestation land, such as natural vegetation attributes and environmental factors. The "weight hierarchy approach" was used to calculate the afforestation quality index of different regions in different 5-year intervals from 2021 to 2060 and extract high-quality potential afforestation lands in each period. By dynamically analyzing the distribution and quality of potential afforestation land from 2021 to 2060, we can identify optimal afforestation sites for each period and formulate a progressive afforestation plan. This approach allows for a more accurate application of the FCS model to evaluate the dynamic changes in the carbon sequestration capacity of newly afforested land from 2021 to 2060. The results indicate that the average potential afforestation land area will reach 75 Mha from 2021 to 2060. In the northern region, afforestation areas are mainly distributed on both sides of the "Hu Line", while in the southern region, they are primarily distributed in the Yunnan–Guizhou Plateau and some coastal provinces. By 2060, the potential calculated cumulative carbon storage of newly afforested lands was 11.68 Pg C, with a peak carbon sequestration rate during 2056–2060 of 0.166 Pg C per year. Incorporating information on the spatiotemporal dynamics of vegetation succession, climate production potential, and vegetation resilience while quantifying the weights of each influencing factor can enhance the accuracy of predictions for potential afforestation lands. The conclusions of this study can provide a reference for the formulation of future afforestation plans and the assessment of their carbon sequestration capacity. [ABSTRACT FROM AUTHOR]

The EU Nature Restoration Law (NRL) is critical for the restoration of degraded ecosystems and active afforestation of degraded peatlands has been suggested as a restoration measure under the NRL. Here, we discuss the current state of scientific evidence on the climate mitigation effects of peatlands under forestry. Afforestation of drained peatlands without restoring their hydrology does not fully restore ecosystem functions. Evidence on long-term climate benefits is lacking and it is unclear whether CO2 sequestration of forest on drained peatland can offset the carbon loss from the peat over the long-term. While afforestation may offer short-term gains in certain cases, it compromises the sustainability of peatland carbon storage. Thus, active afforestation of drained peatlands is not a viable option for climate mitigation under the EU Nature Restoration Law and might even impede future rewetting/restoration efforts. Instead, restoring hydrological conditions through rewetting is crucial for effective peatland restoration. [ABSTRACT FROM AUTHOR]

Forested areas provide various services, including crucial carbon sequestration for climate change mitigation. The Madhupur Sal Forest (MSF) in Bangladesh was studied extensively for its ecosystem services and carbon sequestration potential. Research conducted from February to August 2023 in Gaira and Dokhola villages assessed local community benefits and biodiversity. Interviews with 50 respondents and analysis of 20 plots were conducted to study carbon sequestration in the MSF. Twenty identified ecosystem services range from fuel and wood to cultural and economic advantages. Eight tree species, totaling 401 trees, were identified, with Ficus hispida being the most effective in annual carbon sequestration. Shorea robusta showed less efficacy in carbon sequestration, resulting in a total forest capture of 12 004 657.8 pounds per year. The study highlights the MSF's significant contribution to global climate change mitigation. Emphasis is placed on the need for enhanced carbon sequestration through forest management, reforestation, and afforestation projects in deforested areas. Despite diverse ecosystem services, the MSF faces threats, necessitating collaborative conservation efforts, sustainable management practices, and community involvement for its vitality. [ABSTRACT FROM AUTHOR]

Afforestation has emerged as a major tool in climate mitigation, but plantations of non-native species can negatively affect biodiversity and ecosystem services. Planting indigenous trees in areas that were formerly forested requires an understanding of landscape history over centennial–millennial timescales derived from palaeoecology. Ancient open and mosaic ecosystems are particularly threatened by the global drive for tree planting, which is based on an assumption of degradation. Assumptions that open or mosaic landscapes are remnants of degraded forests is a type of attribution error that can be corrected through an understanding of landscape history. Cultural landscape mosaics can also have benefits in terms of biodiversity and ecosystem services when compared with closed-canopy forests. We propose that testing a null hypothesis regarding former forest cover will assist in correct landscape attribution, guiding reforestation and restoration that reflects landscape history and local context. Mitigating climate change while safeguarding biodiversity and livelihoods is a major challenge. However, rampant afforestation threatens biodiversity and livelihoods, with questionable benefits to carbon storage. The narrative of landscape degradation is often applied without considering the history of the landscape. While some landscapes are undoubtedly deforested, others existed in open or mosaic states before human intervention, or have been deliberately maintained as such. In psychology, a 'fundamental attribution error' is made when characteristics are attributed without consideration of context or circumstances. We apply this concept to landscapes, and then propose a process that avoids attribution errors by testing a null hypothesis regarding past forest extent, using palaeoecology and other long-term data, alongside ecological and stakeholder knowledge. [ABSTRACT FROM AUTHOR]

As forest-based climate change mitigation has become a crucial element of international climate policy it is of increasing importance to understand the processes leading to the carbon offsetting capacity of the sector. In our study, we assessed the climate benefits of contrasting forest management strategies: decreasing harvest and enlarging the forest carbon stock, or increasing harvest to increase carbon uptake, wood product carbon pools, and substitution effects. We developed the Forest Industry Carbon Model (FICM) which is a new carbon accounting tool covering forest biomass, dead organic matter, soil, and harvested wood product pools, as well as avoided emissions through product and energy substitution. We modeled the carbon balance of the Hungarian forest industry under three different scenarios. In the business as usual (BAU) scenario, we assumed no changes in the current harvest and afforestation levels. In the extensification scenario, we assumed that the harvest and afforestation levels drop to half, while in the intensification scenario, we assumed an increase in afforestation, improved industrial wood assortments, and a gradual increase in logging, reaching the highest level as per sustainability criteria by 2050. Our results show that the intensification scenario is characterized by the largest net removals and the maximized product and energy substitution effects. By 2050, the net forest industry carbon balance reaches −8447 kt CO2 eq under the BAU scenario, while −7011 kt CO2 eq is reached under the extensification scenario and −22,135 kt CO2 eq is reached under the intensification scenario. Although substitution effects are not accounted for under the land-based (LULUCF) sector in the greenhouse gas inventory, the emission reductions in the industry and energy sectors have beneficial effects on the national carbon balance. Modeling results show that the 2030 LULUCF greenhouse gas removal target set by EU legislation for Hungary is reached under the intensification scenario. To achieve this outcome, widespread innovation is needed in the wood sector. The modeling results show that nonutilization of forests can only be a very short-term solution; however, its favorable effects will be reversed by 2050 resulting in additional emissions compared to the BAU scenario. [ABSTRACT FROM AUTHOR]

Large-scale reforestation, afforestation, and forest restoration schemes have gained global support as climate change mitigation strategies due to their significant carbon dioxide removal (CDR) potential. However, there has been limited research into the unintended consequences of forestation from a biophysical perspective. In the Community Earth System Model version 2 (CESM2), we apply a global forestation scenario, within a Paris Agreement-compatible warming scenario to investigate the land surface and hydroclimate response. Compared to a control scenario where land use is fixed to present-day levels, the forestation scenario is up to 2 °C cooler at low latitudes by 2100, driven by a 10 % increase in evaporative cooling in forested areas. However, afforested areas where grassland or shrubland are replaced lead to a doubling of plant water demand in some tropical regions, causing significant decreases in soil moisture (~5 % globally, 5–10 % regionally) and water availability (~10 % globally, 10–15 % regionally) in regions with increased forest cover. While there are some increases in low cloud and seasonal precipitation over the expanded tropical forests, with enhanced negative cloud radiative forcing, the impacts on large-scale precipitation and atmospheric circulation are limited. This contrasts with the precipitation response to simulated large-scale deforestation found in previous studies. The forestation scenario demonstrates local cooling benefits without major disruption to global hydrodynamics beyond those already projected to result from climate change, in addition to the cooling associated with CDR. However, the water demands of extensive forestation, especially afforestation, have implications for its viability given uncertainty in future precipitation changes. [ABSTRACT FROM AUTHOR]

Afforestation is a promising nature-based climate solution for mitigating climate change, but it is subject to a complex web of biophysical, cost-benefit, market, and policy processes. Although its biophysical feasibility has been established, the cost, market, and policy constraints that affect climate change mitigation through afforestation are still unclear. Here, we estimate such cost, market, and policy constraints on the basis of biophysical feasibility. Our findings reveal that implementation costs are a more relevant constraint than opportunity costs on mitigating climate change through afforestation. The China Certified Emission Reduction market currently provides only a 0.308 % incentive for climate change mitigation through afforestation, due to market access constraints. The current market prices of China Certified Emission Reduction, China Carbon Emissions Trading Exchange, and Nature Based Carbon Offset in Voluntary Carbon Market constrain 88.15 %, 87.95 %, and 85.75 % of CO2 removal actions through afforestation, compared to the carbon price scenario (US$62.97 tCO2-1) of the EU Emissions Trading System. Moreover, land policy under the scenarios of prohibiting conversion of cultivated land to forest and forest restoration in degraded areas exhibit 8.87–29.59 % and 65.16–74.10 % constraints, respectively, on mitigating climate change through afforestation compared to land-use freedom conversion scenarios from 2020 to 2060. Thus, enhancing the incentive price of CO2 removal, addressing the market access barrier, strengthening cooperation between global carbon markets, and exploring carbon–neutral and food multi-oriented land policies can be valuable sources of mitigation efforts over the next 40 years.

The Chilean Climate Change Law excludes tree monocultures as a solution to the climate crisis, offering an opportunity for resilience and climate mitigation in Latin America. The Chilean experience with mega-fires in extensive, homogeneous forest plantations provides important lessons that could inform climate policies in other countries. [ABSTRACT FROM AUTHOR]

Mitigation actions needed to achieve the ambitions of the Paris agreement to limit global temperature rise to 1.5 °C or below 2 °C have to align with sustainable development. In the near term, this implies a better understanding of context-specific challenges in integrating sustainability with climate policies during the designing, planning, implementation and financing stages. Through a review of selected studies across regions, this paper draws out conclusions focussing on mitigation–sustainable development goal (SDG) trade-offs, with implications on costs and equity for different development contexts. Studies show that trade-offs depend on how the option is implemented and at what scale; mitigation options such as afforestation, biomass production and digitalisation are examples of this. Some options could also result in significant adverse environmental impacts as in the case of battery waste and raw material resources for electric vehicle (EV) or air pollution associated with compact urban development. We find the most important factors influencing equity include unequal access (e.g. urban green spaces and public transportation), high costs (e.g. EV) and financial constraints. Major knowledge gaps include (i) limited empirical evidence of SDG-related trade-offs associated with scaling up mitigation options, (ii) limited understanding of the extent to which benefits are experienced by different groups, (iii) an understanding of the extent to which local context was considered when assessing mitigation–SDG interaction, including the engagement of stakeholders and (iv) synergies and trade-offs associated with cross-sectoral policies. The paper recommends ex-post analysis of detailed and place-based cases that document how synergies and trade-offs emerged and how these were addressed. [ABSTRACT FROM AUTHOR]

The conservation, restoration, and improved management of terrestrial forests significantly contributes to mitigate climate change and its impacts, as well as providing numerous co‐benefits. The pressing need to reduce emissions and increase carbon removal from the atmosphere is now also leading to the development of natural climate solutions in the ocean. Interest in the carbon sequestration potential of underwater macroalgal forests is growing rapidly among policy, conservation, and corporate sectors. Yet, our understanding of whether carbon sequestration from macroalgal forests can lead to tangible climate change mitigation remains severely limited, hampering their inclusion in international policy or carbon finance frameworks. Here, we examine the results of over 180 publications to synthesise evidence regarding macroalgal forest carbon sequestration potential. We show that research efforts on macroalgae carbon sequestration are heavily skewed towards particulate organic carbon (POC) pathways (77% of data publications), and that carbon fixation is the most studied flux (55%). Fluxes leading directly to carbon sequestration (e.g. carbon export or burial in marine sediments) remain poorly resolved, likely hindering regional or country‐level assessments of carbon sequestration potential, which are only available from 17 of the 150 countries where macroalgal forests occur. To solve this issue, we present a framework to categorize coastlines according to their carbon sequestration potential. Finally, we review the multiple avenues through which this sequestration can translate into climate change mitigation capacity, which largely depends on whether management interventions can increase carbon removal above a natural baseline or avoid further carbon emissions. We find that conservation, restoration and afforestation interventions on macroalgal forests can potentially lead to carbon removal in the order of 10's of Tg C globally. Although this is lower than current estimates of natural sequestration value of all macroalgal habitats (61–268 Tg C year−1), it suggests that macroalgal forests could add to the total mitigation potential of coastal blue carbon ecosystems, and offer valuable mitigation opportunities in polar and temperate areas where blue carbon mitigation is currently low. Operationalizing that potential will necessitate the development of models that reliably estimate the proportion of production sequestered, improvements in macroalgae carbon fingerprinting techniques, and a rethinking of carbon accounting methodologies. The ocean provides major opportunities to mitigate and adapt to climate change, and the largest coastal vegetated habitat on Earth should not be ignored simply because it does not fit into existing frameworks. [ABSTRACT FROM AUTHOR]

Context: Afforestation has been widely implemented to deliver climate change mitigation and restore ecosystem benefits. However, the efficacy of afforestation has been deputed. The regeneration ability of most plantations in Northern China has been suggested to fail to reach their optimal. Objectives: Here, we compared the regeneration ability of plantations and natural forests in Northern China and explored how the climate factors and site features can determine the regeneration ability. We hypothesize that the deficient regeneration ability of plantations is mainly due to the single tree age and high stand density. Furthermore, the effects of climate factors cannot be ignored. Methods: We investigated the climate factor, stand features, tree radial growth, and regeneration ability (the number of cones and seedlings) of two dominant conifers, Larix principis-rupprechtii and Pinus sylvestris var. mongolica in natural forests and plantations in northern China. Results: Our analysis shows a significant difference in the number of both cones and regenerated seedlings produced by plantations and natural forests within the same site (P < 0.05). The stand density of plantations had a significant negative effect on the generation of seedlings (P < 0.05). Additionally, climatic factors, such as mean annual temperature and mean precipitation play a major role in regulating the heat and water availability for forest regeneration. Finally, we found that the inter-annual fluctuations in the radial growth of trees are also related to the number of seedlings produced, which is likely due to higher growth fluctuations indicating poorer drought adaptation of trees. Conclusions: Our study suggests that no single factor can explain the regeneration failure of plantations in semi-humid and semiarid regions of China. Both site features and climatic factors affect the production of seedlings. Future afforestation should follow low-density afforestation in areas with favorable climatic conditions for tree growth. [ABSTRACT FROM AUTHOR]

Mangroves in the Arabian Gulf provide several biological, ecological, and environmental services. They are also considered among the largest carbon sinks. However, mangroves along the coastlines of the Arabian Gulf have degraded in recent decades, mainly due to urbanization and coastal development. Therefore, restoration and afforestation programs have been initiated to enhance the services and functions of mangrove ecosystems and as part of national targets to mitigate climate change. Increasing carbon sinks by quadrupling the current areas covered by mangroves through afforestation programs by 2035 is one of the strategies to mitigate climate change in Bahrain. The aim of the present study was to estimate the organic carbon stocks in the sediments of natural and transplanted mangroves in Bahrain. Within the protected areas of Tubli and Arad Bays, sediment samples were taken down to a depth of 70 cm from natural and transplanted mangroves as well as a bare mudflat. The findings of the present study indicated that the total sediment organic carbon concentrations at three sampling sites of natural and transplanted mangroves and the mudflat were 200.54 ± 24.52, 112.36 ± 55.51, and 81.56 ± 8.92 Mg C/ha, respectively. The natural mangroves in Tubli Bay differed considerably from those in Arad Bay (p ≤ 0.001), based on the concentrations of organic carbon in sediments. However, there was a noticeable similarity seen in the organic carbon of the mangroves in Arad Bay that were transplanted 25 years prior and the natural mangroves in Tubli Bay, indicating the importance of a long-term mangrove afforestation strategy to mitigate climate change in the Arabian Gulf. [ABSTRACT FROM AUTHOR]

Afforestation and reforestation can contribute to the mitigation of climate change by increasing forested areas that can actively sequester carbon dioxide from the atmosphere through photosynthesis. The purpose of this study was to assess the potential for carbon sequestration in the ecosystem and in harvested wood products, and associated greenhouse gas (GHG) emission mitigation, following the application of afforestation/reforestation strategies on unproductive lands in the Province of Quebec over an 80-year long period (2021–2101), using the Carbon Budget Model of the Canadian Forester Sector 3. Afforestation/reforestation scenarios without harvesting and scenarios based on establishment of fast-growing species such as hybrid poplar showed the greatest short-term (2020–2040) carbon sequestration potential. Over the 80-year simulation period, plantations without harvesting generated a greater potential for carbon sequestration in ecosystems; after each harvesting event, several decades were necessary to regain any ecosystem carbon loss, which could be compensated only if a proportion of the harvested wood is converted to long-lived wood products, with high substitution effects in other sectors. In the northern boreal zone of Quebec, significant mitigation potential can be expected from the afforestation of open woodlands and poorly regenerated burns, both with or without harvesting. In the southern zone, the need for better data on vegetation succession and carbon accumulation on abandoned farmlands in the absence of plantations was highlighted by this study. This study increases the understanding of carbon sequestration by plantations, and their role as a mitigation strategy to contribute to national GHG emission reduction targets and net-zero carbon objectives. [ABSTRACT FROM AUTHOR]

The article proposes three ways to build on the Intergovernmental Panel on Climate Change (IPCC) analyses of carbon dioxide removal (CDR) mitigation potential by assessing sustainability risks associated with land use change and biodiversity loss. These include estimating the sustainable CDR budget based on socioecological thresholds, identifying viable mitigation pathways that do not overstep these thresholds, and reframing emerging CDR governancce.

A growing number of initiatives at global, regional and national scales propose to plant millions, billions or even trillions of trees as a simple solution to resolve complex environmental problems. However, tree planting is much more complicated than it seems. We summarize the multifaceted decision‐making process needed and offer guidelines to increase the success of the proposed ambitious efforts to increase tree cover world‐wide. Given the varied definitions of and motivations for tree planting, it is critical that stakeholders work together to clearly define the biophysical and socioeconomic goals of each project. Then a series of questions must be addressed about where and how (e.g. planting trees vs. allowing for natural forest regrowth) to most effectively achieve these goals and minimize unintended negative consequences, as well as how, when and by whom success of efforts will be evaluated. Key guidelines to successfully increase tree cover include: (a) first addressing the underlying drivers of deforestation; (b) integrating decision‐making across scales from local to global; (c) tailoring tree planting strategies to clearly stated project goals and planning, adaptively managing and evaluating success over a sufficiently long timeframe; (d) focusing on the forest ecosystem as a whole, and not just the trees; (e) coordinating different land uses and (f) involving stakeholders at all stages of the planning process. Synthesis and applications. Tree planting, along with other strategies to increase tree cover in appropriate locations and contexts, can make a valuable contribution to ensuring the ecological and social well‐being of our planet in coming decades, but only if these efforts are considered as one component of multifaceted solutions to complex environmental problems and are carefully planned, implemented and monitored over a sufficiently long time‐scale with stakeholder engagement and broader consideration of socio‐ecological complexities.

The tropical forest carbon (C) balance threatened by extensive socio‐economic development in the Greater Mekong Subregion (GMS) in Asia is a notable data gap and remains contentious. Here we generated a long‐term spatially quantified assessment of changes in forests and C stocks from 1999 to 2019 at a spatial resolution of 30 m, based on multiple streams of state‐of‐the‐art high‐resolution satellite imagery and in situ observations. Our results show that (i) about 0.54 million square kilometers (21.0% of the region) experienced forest cover transitions with a net increase in forest cover by 4.3% (0.11 million square kilometers, equivalent to 0.31 petagram of C [Pg C] stocks); (ii) forest losses mainly in Cambodia, Thailand, and in the south of Vietnam, were also counteracted by forest gains in China due mainly to afforestation; and (iii) at the national level during the study period an increase in both C stocks and C sequestration (net C gain of 0.087 Pg C) in China from new plantation, offset anthropogenetic emissions (net C loss of 0.074 Pg C) mainly in Cambodia and Thailand from deforestation. Political, social, and economic factors significantly influenced forest cover change and C sequestration in the GMS, positively in China while negatively in other countries, especially in Cambodia and Thailand. These findings have implications on national strategies for climate change mitigation and adaptation in other hotspots of tropical forests. [ABSTRACT FROM AUTHOR]

Afforestation and reforestation (AR) on marginal land are nature-based solutions to climate change. There is a gap in understanding the climate mitigation potential of protection and commercial AR with different combinations of forest plantation management and wood utilization pathways. Here, we fill the gap using a dynamic, multiscale life cycle assessment to estimate one-century greenhouse gas (GHG) mitigation delivered by (both traditional and innovative) commercial and protection AR with different planting density and thinning regimes on marginal land in the southeastern United States. We found that innovative commercial AR generally mitigates more GHGs across 100 y (3.73 to 4.15 Giga tonnes of CO2 equivalent (Gt CO2e)) through cross-laminated timber (CLT) and biochar than protection AR (3.35 to 3.69 Gt CO2e) and commercial AR with traditional lumber production (3.17 to 3.51 Gt CO2e), especially in moderately cooler and dryer regions in this study with higher forest carbon yield, soil clay content, and CLT substitution. In a shorter timeframe (=50 y), protection AR is likely to deliver higher GHG mitigation. On average, for the same wood product, low-density plantations without thinning and high-density plantations with thinning mitigate more life cycle GHGs and result in higher carbon stock than that of low-density with thinning plantations. Commercial AR increases the carbon stock of standing plantations, wood products, and biochar, but the increases have uneven spatial distributions. Georgia (0.38 Gt C), Alabama (0.28 Gt C), and North Carolina (0.13 Gt C) have the largest carbon stock increases that can be prioritized for innovative commercial AR projects on marginal land. [ABSTRACT FROM AUTHOR]

Plantation tree species have an immense potential for significantly reducing the atmospheric carbon dioxide and hence regulating climate change. The present study assessed the role of tree species to store carbon and soil enrichment in the eastern plateau and hill region of India. The species investigated were Leucaena leucophala, Gmelina arborea, Cassia siamea, and Eucalyptus tereticornis. The plantation of trees was found to have higher levels of soil organic carbon (SOC) (0.53–0.62%), nitrogen (239.12–253.01 kg ha−1), phosphorus (37.02–38.79 kg ha−1), and potassium (175.47–237.22 kg ha−1) over the non-forested land (control) but was lower in the levels of pH (5.28–5.95) and bulk density (1.32–1.52 g cm−3). However, as soil depth increased, the nutritional status of both plantation and non-forested land soil decreased. The per cent SOC was the highest in surface layers, while the bulk density was the highest in sub-surface layers under different forest plantations. The maximum SOC (0.62%) and bulk density (1.52 g cm−3) were present in Gmelina arborea and Eucalyptus tereticornis plantation, respectively. Among the studied tree species, the soil carbon density and carbon sequestration potential (CSP) were found to be maximum (13.56 t ha−1 and 1.28 t ha−1 year−1) in Gmelina arborea followed by Eucalyptus tereticornis, Cassia siamea, and Leucaena leucocephala, respectively, depicting that these tree species have a stronger capacity to sequester and store carbon, making them suitable as atmospheric carbon reducers. The study also demonstrated that forest plantation enhanced the SOC, nutrient stock, and other crucial soil fertility indicators compared to non-forested site. [ABSTRACT FROM AUTHOR]

Understanding the perceptions of young people is a critical issue in the formulation and implementation of climate change mitigation strategies. Based on cognitive hierarchy theory, the present study aims to investigate the factors that motivate or hinder young people's perception of forestation as a strategy to mitigate climate change in post-conflict Somalia. This study hypothesized a model in which climate change knowledge, risk perception and forest value orientations (anthropocentric/biocentric) influence attitude toward forestation and attitude, in turn, predicts behavioral intentions. We randomly surveyed students from three universities in three different regions of Somalia and collected 434 structured survey questionnaires. Using structural equation modeling, the results showed that climate change knowledge is a significant predictor of behavioral intention but not attitude toward forestation. The results also revealed that young people's perception toward forestation as a strategy to mitigate climate change is significantly influenced by biocentric value orientation both directly and indirectly through attitude toward forestation. Contrary to previous studies, our results indicate that attitude partially mediates the relationship between biocentric value orientation and behavioral intentions and fully mediates the relationship between anthropocentric value orientation, risk perception and behavioral intentions, while it did not show any mediation results between climate change knowledge and behavioral intention. We found that the young people's climate action or inaction is mainly shaped by climate change knowledge, biocentric value orientation, and attitude toward forestation. Finally, climate change mitigation efforts should avoid relying solely on attitude for behavioral decision-making formation and instead incorporate other factors into a more comprehensive framework. [ABSTRACT FROM AUTHOR]

Afforestation and reduction of fossil fuel emissions are two major components of climate mitigation policies. However, their effects on the Earth's climate are different because a reduction of fossil fuel emissions directly alters the biogeochemical cycle of the climate system and modifies the physics of the atmosphere via its impact on radiation and the energy budget, while afforestation causes biophysical changes in addition to changes in the biogeochemical cycle. In this paper, we compare the climate and carbon cycle consequences of carbon removal by afforestation and an equivalent fossil fuel emission reduction using simulations from an intermediate complexity Earth system model. We performed two major sets of idealized simulations in which fossil fuel emissions follow extended Shared Socioeconomic Pathway (SSP) scenarios (SSP2-4.5, 3-7.0, and 5-8.5), and equal amounts of carbon are removed by afforestation in one set and by a reduction in fossil fuel emissions in another set. Our simulations show that the climate is cooler by 0.36, 0.47, and 0.42 ∘C in the long term (2471–2500) in the case of reduced fossil fuel emissions compared to the case with afforestation when the emissions follow the SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, respectively. The global mean surface temperature is cooler in the reduced fossil fuel emissions case compared to the afforestation case because the net biophysical effect of warming from afforestation partly offsets the biogeochemical cooling effect of afforestation. Thus, in terms of climate benefits, reducing fossil fuel emissions could be relatively more beneficial than afforestation for the same amount of carbon removed from the atmosphere. However, a robust understanding of the processes that govern the biophysical effects of afforestation should be improved before considering our results for climate policy. [ABSTRACT FROM AUTHOR]

Afforestation is a good strategy for climate change mitigation through increasing carbon stocks. This study determined changes in soil respiration (SR) brought about by the afforestation of high quality agricultural land in a temperate-humid region (Galicia, NW Spain), identified the variables that explain the observed changes and determined the main factors regulating SR temporal variation. Paired plots of fertile soils (cropped vs. afforested plots) were established in two similar areas (Pontevea and Laraño) where afforestation with Populus x euroamericana (Dode) Guinier was carried out in the same year. Different management practices and crop rotations were used (maize–pasture, Laraño and maize–fallow, Pontevea). The SR was measured in situ with a CO2 static chamber every 15 days (every month in winter) for 16 months; soil temperature (Ts) and soil moisture content (W) were also measured. In both areas, significant differences (p < 0.05) in SR between paired plots were related to soil organic C content and SR was mainly influenced by Ts, except during the summer period where SR fluctuations were accompanied by W fluctuations. These findings show that growing pasture crops on high quality land can prevent the loss of soil N and C and probably improve the greenhouse gas balance in the system. [ABSTRACT FROM AUTHOR]

Forests-based measures such as afforestation/reforestation (A/R) and reducing deforestation (RDF) are considered promising options to mitigate climate change, yet their mitigation potentials are limited by economic and biophysical factors that are largely uncertain. The range of mitigation potential estimates from integrated assessment models raises concerns about the capacity of land systems to provide realistic, cost-effective and permanent land-based mitigation. We use the Global Change Analysis Model to quantify the economic mitigation potential of forests-based measures by simulating a climate policy including a tax on greenhouse gas emissions from agriculture, forestry, and other land uses. In addition, we assess how constraining unused arable land (UAL) availability, forestland expansion rates, and global bioenergy demand may influence the forests-based mitigation potential by simulating scenarios with alternative combinations of constraints. Results show that the average forests-based mitigation potential in 2020–2050 increases from 738 MtCO _2 .yr ^−1 through a forestland increase of 86 Mha in the fully constrained scenario to 1394 MtCO _2 .yr ^−1 through a forestland increase of 146 Mha when all constraints are relaxed. Regional potentials in terms of A/R and RDF differ strongly between scenarios: unconstrained forest expansion rates mostly increase A/R potentials in northern regions (e.g., +120 MtCO _2 .yr ^−1 in North America); while unconstrained UAL conversion and low bioenergy demand mostly increase RDF potentials in tropical regions (e.g., +76 and +68 MtCO _2 .yr ^−1 in Southeast Asia, respectively). This study shows that forests-based mitigation is limited by many factors that constrain the rates of land use change across regions. These factors, often overlooked in modelling exercises, should be carefully addressed for understanding the role of forests in global climate mitigation and defining pledges towards the Paris Agreement.

Mangroves in the Arabian Gulf provide several biological, ecological, and environmental services. They are also considered among the largest carbon sinks. However, mangroves along the coastlines of the Arabian Gulf have degraded in recent decades, mainly due to urbanization and coastal development. Therefore, restoration and afforestation programs have been initiated to enhance the services and functions of mangrove ecosystems and as part of national targets to mitigate climate change. Increasing carbon sinks by quadrupling the current areas covered by mangroves through afforestation programs by 2035 is one of the strategies to mitigate climate change in Bahrain. The aim of the present study was to estimate the organic carbon stocks in the sediments of natural and transplanted mangroves in Bahrain. Within the protected areas of Tubli and Arad Bays, sediment samples were taken down to a depth of 70 cm from natural and transplanted mangroves as well as a bare mudflat. The findings of the present study indicated that the total sediment organic carbon concentrations at three sampling sites of natural and transplanted mangroves and the mudflat were 200.54 ± 24.52, 112.36 ± 55.51, and 81.56 ± 8.92 Mg C/ha, respectively. The natural mangroves in Tubli Bay differed considerably from those in Arad Bay (p ≤ 0.001), based on the concentrations of organic carbon in sediments. However, there was a noticeable similarity seen in the organic carbon of the mangroves in Arad Bay that were transplanted 25 years prior and the natural mangroves in Tubli Bay, indicating the importance of a long-term mangrove afforestation strategy to mitigate climate change in the Arabian Gulf.

Increasing ecosystem service provision is a key strategy of the UK’s ongoing agricultural and environmental policy reforms. Enhancing forest cover by 4%, particularly on the least productive agricultural land, aims to maximise carbon sequestration and achieve net zero by 2050. Multiple factors affect the sequestration potential of afforestation schemes and landowner participation in them, highlighting the need for spatially explicit research. We used the InVEST Carbon Model to investigate the Loddon Catchment, southeast England as a study area. We assessed the carbon sequestration potential and economic feasibility of three broadleaved woodland planting scenarios; arable, pasture, and stakeholder-approved (SA) scenario. We found that over a 50-year time horizon, woodland planting on arable land has the greatest sequestration potential (4.02 tC ha−1 yr−1), compared to planting on pasture land (3.75 tC ha−1 yr−1). When monetising carbon sequestration at current market rates, woodland planting on agricultural land incurs a loss across all farm types. However, when including the value of unpaid labour, lowland pasture farms presently incur a greater loss (−€285.14 ha−1 yr−1) than forestry (−€273.16 ha−1 yr−1), making forestry a more economical land use. Subsidising up to the social value of carbon (€342.23 tC−1) significantly reduces this loss and may make afforestation of pasture land more appealing to farmers. Woodland planting on lowland pasture land would increase forest cover by up to 3.62%. However, due to the influence of farmer attitudes on participation, it is more realistic for afforestation to occur on lowland pasture land in the SA scenario, equating to a 0.74% increase.

Afforestation is an important mitigation strategy for climate change due to its carbon sequestration potential. Besides this favorable biogeochemical effect on global CO 2 concentrations, afforestation also affects the regional climate by changing the biogeophysical land surface characteristics. In this study, we investigate the effects of an idealized global CO 2 reduction to pre-industrial conditions by a Europe-wide afforestation experiment on the regional longwave radiation balance, starting in the year 1986 on a continent entirely covered with grassland. Results show that the impact of biogeophysical processes on the surface temperatures is much stronger than that of biogeochemical processes. Furthermore, biogeophysically induced changes of the surface temperatures, atmospheric temperatures, and moisture concentrations are as important for the regional longwave radiation balance as the global CO 2 reduction. While the outgoing longwave radiation is increased in winter, it is reduced in summer. In terms of annual total, a Europe-wide afforestation has a regional warming effect despite reduced CO 2 concentrations. Thus, even for an idealized reduction of the global CO 2 concentrations to pre-industrial levels, the European climate response to afforestation would still be dominated by its biogeophysical effects. [ABSTRACT FROM AUTHOR]

Afforestation and reduction of fossil fuel emissions are two major components of climate mitigation policies. However, their effects on the earth's climate are different because reduction of fossil fuel emissions directly alters the biogeochemical cycle of the climate system, while afforestation causes biophysical changes in addition to changes in the biogeochemical cycle. In this paper, we compare the climate and carbon cycle consequences 15 of carbon removal by afforestation and an equivalent fossil fuel emission reduction using simulations from an intermediate complexity Earth system model. Our simulations show that the climate is cooler by 0.36°C, 0.47°C, and 0.42°C in the long term (2471-2500) in the case of reduced fossil fuel emissions compared to the case with afforestation when the emissions follow the SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios, respectively. Though afforestation results in a lower atmospheric CO2, the cooling from the reduced atmospheric CO2 is partly offset by the warming from surface albedo decrease associated with the regrowth of forests. Since this warming effect from surface albedo decrease is nearly absent in the reduced fossil fuel emission case, the climate is relatively cooler, even though the atmospheric CO2 levels are similar to the afforestation case. Thus, in terms of climate benefits, reducing fossil fuel emissions is relatively more beneficial than afforestation for the same amount of carbon removed from the atmosphere. Nevertheless, fossil fuel emission reduction and afforestation efforts should be pursued simultaneously as both lead to a decrease in global mean warming and reduced ocean acidification. [ABSTRACT FROM AUTHOR]

Afforestation is an important mitigation strategy to climate change due to its carbon sequestration potential. Besides this positive biogeochemical effect on global CO2 concentrations, afforestation also affects the regional climate by changing the biogeophysical land surface characteristics. In this study, we investigate the effects of an idealized global CO2 reduction to pre-industrial conditions by a Europe wide afforestation experiment on the regional longwave radiation balance, starting in the year 1986 from a continent entirely covered with grassland. Results show that the impact of biogeophysical processes on the surface temperatures is much stronger than of biogechemical processes. Furthermore, biogeophysically induced changes of the surface temperatures, atmospheric temperatures and moisture concentrations are as important for the regional greenhouse effect as the global CO2 reduction. While the greenhouse effect is strengthened in winter, it is weakened in summer. On annual total, a Europe-wide afforestation has a regional warming effect, despite reduced CO2 concentrations. Thus, even for an idealized reduction of the global CO2 concentrations to pre-industrial levels, the European climate response to afforestation would still be dominated by its biogeophysical effects. [ABSTRACT FROM AUTHOR]

This article argues that in order to achieve climate justice, recognition needs to be given more attention in climate research, discourse, and policies. Through the analysis of three examples, we identify formal and discursive recognition as central types of recognition in climate issues, and we show how powerful actors exercise their power in ways that cause climate injustice through formal and discursive misrecognition of poor and vulnerable groups. The three examples discussed are: climate mitigation through forest conservation (REDD), the Great Green Wall project in the Sahel, and the narrative about climate change as a contributing factor to the Syrian war. [ABSTRACT FROM AUTHOR]

Afforestation is important for the EU forest management strategy. Afforestation of abandoned and marginal arable land is a favourable non-agricultural land use option for climate change mitigation. It may prevent threats of drought or erosion e.g. by affecting the water balance in soil via increased structural stability. The structural stability control in afforested soil is related to i.a. organic matter content, nutrient content, soil reaction, planted tree species prosperity, and amelioration. A four-year field small-plot experiment on afforestation was carried out with Chernozem covered with deciduous (oak), coniferous (pine) or mixed planting, amended with 3 doses (no-application, 0.5 kg.m-2, and 1.5 kg.m-2) of alginite. In 2013 and 2016, soil reaction pHH2O, mean weight diameter (MWD), organic matter content (LOI) and total organic carbon (TOC) were determined and related to the soil structural stability to evaluate the soil precondition to sustain drought twice per vegetation period (spring and autumn). Afforestation significantly improved MWD compared to the field soil between 2013 and 2016 from 1.63 ± 0.04 mm to 1.85 ± 0.05 mm. Tree planting significantly neutralized the soil pHH2O, mixed planting appeared to improve LOI and TOC. Four-year afforestation led also to higher structural stability, less alkaline pH and deciduous tree-related increase in LOI, which may indicate better soil sustainability to drought. [ABSTRACT FROM AUTHOR]

Afforestation and land use changes that sequester carbon from the atmosphere in the form of woody biomass have turned southern China into one of the largest carbon sinks globally, which contributes to mitigating climate change. However, forest growth saturation and available land that can be forested limit the longevity of this carbon sink, and while a plethora of studies have quantified vegetation changes over the last decades, the remaining carbon sink potential of this area is currently unknown. Here, we train a model with multiple predictors characterizing the heterogeneous landscapes of southern China and predict the biomass carbon carrying capacity of the region for 2002–2017. We compare observed and predicted biomass carbon density and find that during about two decades of afforestation, 2.34 PgC have been sequestered between 2002 and 2017, and a total of 5.32 Pg carbon can potentially still be sequestrated. This means that the region has reached 73% of its aboveground biomass carbon carrying capacity in 2017, which is 12% more than in 2002, equal to a decrease of 0.77% per year. We identify potential afforestation areas that can still sequester 2.39 PgC, while old and new forests have reached 87% of their potential with 1.85 PgC remaining. Our work locates areas where vegetation has not yet reached its full potential but also shows that afforestation is not a long‐term solution for climate change mitigation. Plain Language Summary: Forests sequester carbon dioxide from the atmosphere in the form of vegetation biomass, and tree planting initiatives are thus suggested as a promising measure against climate change. China has recently planted millions of trees, which sequester large amounts of carbon, but this carbon sink is not infinite. We quantify the amount of carbon that can still be sequestered in the forests of southern China. We find that 73% of the limits have been reached in 2017, which is 12% more than in 2002, when the tree planting initiatives started. This illustrates that planting trees is only a short term solution and only a reduction of CO2 emissions helps to mitigate climate change in the long term. Key Points: We estimate the aboveground forest biomass of southern China to be 15.22 PgC in 2017 and the carrying capacity is 20.54 PgCAfforestation starting in 2002 has consumed 2.34 PgC, but 5.32 PgC of potential carbon sinks are leftAfforestation approaches the carbon sink limits quickly and is not a long term measure to achieve carbon neutrality [ABSTRACT FROM AUTHOR]

Tree planting now forms a major part of the UK climate mitigation strategy, with targets to increase the forest cover from the current 13% to 17%–20% by 2050. A tree planting strategy on this scale requires a significant amount of planning, bringing together expertise from a wide range of practitioners. We highlight four key reasons why fungi should be considered in tree planting strategies: 1. Fungi can cause severe tree disease. 2. Fungi can cause significant human health burdens. 3. Forest soil carbon and nutrient cycling is controlled by fungi. 4. Climate change is already affecting fungi. Following from these four reasons, we explore the ways in which the negative effects of fungi, such as plant and human disease, can be mitigated against, whilst also protecting and promoting the benefits of fungi in carbon storage and biodiversity. Based on this, we outline seven guidelines which should be integrated into existing tree planting guidelines and UK policy: A. Monitor tree fungal disease emergence and spread, including in source material trade (e.g. seeds and saplings). B. Choose tree species combinations appropriate to the specific habitat and appropriate for biodiversity and carbon storage goals. C. Develop and implement a widely accessible fungal spore forecast to complement existing pollen forecasts. D. Protect existing ancient and mature woodlands. E. Promote planting on suitable land types, avoiding grasslands and wetlands. F. Assess proposed and existing forest sites, ideally using a combination of fungal fruit body surveys and eDNA techniques. G. Develop and implement the UK Fungi Red List into UK law. [ABSTRACT FROM AUTHOR]

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Since 2019, China has emerged as a leading proponent of nature-based solutions (NbS) to improve global environmental management. These solutions – from regrowing forests to restoring wetlands to regenerating agricultural soils to greening cities – can, at least in theory, simultaneously reduce greenhouse gas emissions, protect biodiversity, and enhance community wellbeing and resilience. For some advocates, nature-based solutions also entail a radical rethinking of how humans should be interacting with nature, requiring new responsibilities, rights, and governance mechanisms. This article explains how and why China has been promoting NbS in multilateral and domestic policy settings. By analyzing the content of English- and Chinese-language policy briefings, diplomatic remarks, and government documents from 2019 to mid-2021, it reveals that China's NbS goals and actions differ significantly in domestic and international settings. Internationally, Chinese policymakers have been reframing the country's pre-existing large-scale afforestation, green financing, disaster risk reduction, and ecotourism projects as NbS, broadly defined. In multilateral forums, meanwhile, Chinese diplomats and practitioners are promoting NbS as an umbrella term to enhance the legitimacy of domestic projects now labelled as NbS, project an image of climate action and global environmental leadership, and increase China's discursive power within global environmental governance. China's embrace of NbS, as this article reveals, has far-reaching consequences for the future of nature-based solutions within multilateral climate and biodiversity governance, with the potential to turn NbS into a diplomatic and rhetorical tool to portray conventional approaches to environmental management as innovative, nature-positive solutions. • Internationally, China is reframing pre-existing policies as nature-based solutions (NbS). • What China is labelling NbS includes large-scale afforestation, green financing, flood controls, and ecotourism projects. • Internationally, China is advocating for NbS to enhance its image and soft power. • China's NbS discourse is mainly aimed at an international audience, with domestic policy and rhetoric largely unchanged. • China's NbS leadership could further mainstream NbS discourses in multilateral forums, but hinder meaningful implementation. [ABSTRACT FROM AUTHOR]

Edge effects occur when the matrix has adverse impacts on the patches of remnant habitat. A widely explored example of this is the hypothesis of a higher predation pressure on bird nests closer to the habitat edge. In parallel with the recent loss of open habitats through afforestation as a climate change mitigation measure, an interest in the impact of forest on species dependent on open habitats has re‐emerged. We follow wader nest survival to study the issue of an edge effect in a system of wet grasslands fragmented by forests in a region where it has not been tested before, focussing mainly on northern lapwing (Vanellus vanellus), common ringed plover (Charadrius hiaticula), common redshank (Tringa totanus) and southern dunlin (Calidris alpina schinzii). To record nest survival, we monitored 753 nests of 10 wader species on coastal grasslands in Estonia for 3 consecutive years. A subset (n = 85) of these nests was equipped with camera traps to record nest predation events and predator association with forest edge. The distance to nearest trees and forest and a forest cover within a 1‐km buffer around each nest was measured. We recorded extremely low daily nest survival rates (0.903–0.922 for different species), with most nests lost to predation. We showed that nest survival is lower closer to the forest edge and negatively affected by the proportion of forest within a 1‐km buffer around each nest. Based on camera trap recordings, we suggest that the edge effect is caused by elevated nest predation rates by the most common predator, the red fox (Vulpes vulpes), closer to the forest edge. Future afforestation plans of open habitats need to acknowledge that the resulting fragmentation has a negative impact on nest survival of ground‐breeding birds. On the other hand, our results imply that restoration efforts aimed at removal of most damaging forest plantations could benefit breeding waders. [ABSTRACT FROM AUTHOR]

One of the key areas in which the United Kingdom government plans to achieve net zero, reduce GHG emissions and sequester carbon is through afforestation. Afforestation will also provide ecosystem services to society. The Scottish government's target is to increase woodland cover in Scotland to 25% by 2050. In this study, a land suitability analysis was used to investigate the likelihood of achieving this target based on the biophysically suitable and available land considering the current policy constraints for planting Sitka spruce (Picea sitchensis) in Scotland. The results showed that about 19% of land area in Scotland is biophysically suitable for Sitka spruce and about 13% is biophysically suitable and available based on policy constraints. Thus, there is an opportunity for the Scottish government to increase the woodland cover in Scotland to 31.5% and exceed its 25% woodland target. However, for Scotland to achieve net zero by 2045, it will require that more trees be planted on higher-quality agricultural land, different from areas where trees are currently planted. [ABSTRACT FROM AUTHOR]

Forestation of the vast global drylands has been considered a promising climate change mitigation strategy. However, its actual climatic benefits are uncertain because the forests’ reduced albedo can produce large warming effects. Using high-resolution spatial analysis of global drylands, we found 448 million hectares suitable for afforestation. This area’s carbon sequestration potential until 2100 is 32.3 billion tons of carbon (Gt C), but 22.6 Gt C of that is required to balance albedo effects. The net carbon equivalent would offset ~1% of projected medium-emissions and business-as-usual scenarios over the same period. Focusing forestation only on areas with net cooling effects would use half the area and double the emissions offset. Although such smart forestation is clearly important, its limited climatic benefits reinforce the need to reduce emissions rapidly. [ABSTRACT FROM AUTHOR]

Rising interest in large-scale afforestation and reforestation as a strategy for climate change mitigation has recently motivated research efforts aiming at the identification of areas suitable for the plantation of trees. An often-overlooked aspect of agroforestry projects for carbon sequestration is their impact on water resources. It is often unclear to what extent the establishment of forest vegetation would be limited by water availability, whether it would engender competition with other local water uses or induce water scarcity. Here we use global water models to study the hydrologic constraints and impacts of afforestation in tropical biomes. We find that 36% of total suitable and available afforestation areas are in areas where the rain alone can meet just up to the 40% of total plant water requirement. Planting trees will substantially increase water scarcity and possible dispossession (green water grab) especially in dryland regions of Africa and Oceania. Moreover, the combination of tree restoration and irrigation expansion to rainfed agricultural areas is expected to further exacerbate water scarcity, with about half of the global suitable areas for tree restoration experiencing water scarcity at least 7 months per year. Thus, the unavailability of water can overall limit climate change adaptation strategies. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'. [ABSTRACT FROM AUTHOR]

Developing effective climate mitigation strategies under global warming requires a comprehensive understanding of the biophysical mechanism of how afforestation affects the climate and environment. The planted forests in southern China are an essential carbon sink. However, the impacts of radiative and non‐radiative processes on land surface temperature caused by converting open land (i.e., grassland and cropland) and natural forests to planted forests remain unclear. We used satellite observations and intrinsic biophysical mechanism theory‐based energy balance models to estimate the biophysical impacts of potential afforestation of open land and natural forests on surface temperature from 2000 to 2010 in Guangdong Province, southern China. Results showed that afforestation of open land had a consistent net cooling effect. Due to the afforestation of natural forests, the modeled results revealed that afforestation among all conversion types had a net warming effect of 0.15 ± 0.5 K, which caused by the change in energy redistribution factor although uncertainty remains. While the most significant warming caused by converting natural forest to planted forests was also slightly affected by albedo. The afforestation's non‐radiative and radiative processes led to a slight warming of 0.143 ± 0.43 K and a cooling of −0.096 ± 0.19 K, respectively. The non‐radiative process dominates the effect of afforestation on the surface temperature, with the overall non‐radiative forcing index greater than 73% ± 0.59%. Our study highlights the need of protecting natural forests and provides a practical method for assessing the impacts of afforestation on the local climate and the effectiveness of climate mitigation efforts. Plain Language Summary: Afforestation is an important tool for mitigating climate change. However, the land cover change induced by afforestation may affect the land‐atmosphere balance of water and energy. Accurate estimation of surface temperature change in response to afforestation‐induced surface energy change is challenging. From 2000 to 2010, afforestation activities in southern China were frequent, resulting in a significant increase in carbon sinks. Yet, how these land‐use changes can affect the local climate is unclear. Here we prepared the high‐resolution land cover data and utilized satellite observations and a physical‐based method to estimate the impacts of afforestation on land surface temperature in southern China. This strategy can provide insights for designing rational afforestation policies in southern China and similar geographic areas. Key Points: The modeled land surface temperature due to afforestation had a net warming effectThe non‐radiative process mainly drives the effect of afforestation on local surface temperatureThe detailed distribution of afforestation and a precise energy balance model allow accurate evaluation of the temperature response [ABSTRACT FROM AUTHOR]

Carbon sequestration is defined as the secure storage of carbon‐containing molecules for >100 years, and in the context of carbon dioxide removal for climate mitigation, the origin of this CO2 is from the atmosphere. On land, trees globally sequester substantial amounts of carbon in woody biomass, and an analogous role for seaweeds in ocean carbon sequestration has been suggested. The purposeful expansion of natural seaweed beds and aquaculture systems, including into the open ocean (ocean afforestation), has been proposed as a method of increasing carbon sequestration and use in carbon trading and offset schemes. However, to verify whether CO2 fixed by seaweeds through photosynthesis leads to carbon sequestration is extremely complex in the marine environment compared to terrestrial systems, because of the need to jointly consider: the comparatively rapid turnover of seaweed biomass, tracing the fate of carbon via particulate and dissolved organic carbon pathways in dynamic coastal waters, and the key role of atmosphere–ocean CO2 exchange. We propose a Forensic Carbon Accounting approach, in which a thorough analysis of carbon flows between the atmosphere and ocean, and into and out of seaweeds would be undertaken, for assessing the magnitude of CO2 removal and robust attribution of carbon sequestration to seaweeds. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this study was to compare the accumulation over time of organic carbon (C) in soil and vegetation of abandoned agricultural lands left to natural vegetation succession or afforested with planted white spruce (Picea glauca (Moench) Voss) in Abitibi (Canada). The agricultural areas of this region originated from the clearing of forested lands in the late 19th -early 20th centuries. The aim was to determine whether afforestation of such lands is a relevant tool for C sequestration and climate change mitigation. Methods: Field and laboratory measures for tree, shrub and herbaceous strata, woody debris and soil down to a 50 cm depth were carried out on abandoned agricultural lands that were either left to natural succession or planted, to determine total C stocks. The experimental design was a chronosequence covering 50 years, with sites representing various stages following agriculture abandonment and plantation. Results: There was no significant difference in the amount of C stored by lands that were either planted or left to natural succession over a 50-year time period. Both types of lands were found to be net C sinks. Abandoned lands left to natural succession stored 1.3 times more C in the soil compared with afforested lands, while the latter stored twice as much C in aboveground biomass. Conclusions: These results put into perspective the use of afforestation to increase land C sinks and suggest that natural succession might also play a role in land management practices in the context of climate change mitigation. [ABSTRACT FROM AUTHOR]

Terrestrial ecosystems play a critical role in the global carbon cycle and climate change mitigation. Studying the temporal and spatial dynamics of carbon sink and the driving mechanisms at the regional scale provides an important basis for ecological restoration and ecosystem management. Taking the Dongting Lake Basin as an example, we assessed the carbon sinks of forest and shrub from 2000 to 2020 based on the maps of biomass that were obtained by remote sensing, and analyzed the dynamics of carbon sinks that were contributed by different biomass carbon density levels of constant forest and shrub and new afforestation over the past two decades. The results showed that the carbon sink of forest and shrub in the Dongting Lake Basin grew rapidly from 2000 to 2020: carbon sink increased from 64.64 TgC between 2000 and 2010, to 382.56 TgC between 2010 and 2020. The continuous improvement of biomass carbon density has made a major contribution to carbon sink, especially the carbon density increase in low carbon density forests and shrubs. Carbon-dense forests and shrubs realized their contribution to carbon sink in the second decade after displaying negative carbon sink in the first decade. Carbon sink from new afforestation increased 61.16% from the first decade to the second decade, but the contribution proportion decreased. The overall low carbon density of forest and shrub in the Dongting Lake Basin and their carbon sink dynamics indicated their huge carbon sequestration potential in the future. In addition to continuously implementing forest protection and restoration projects to promote afforestation, the improvement of ecosystem quality should be paid more attention in ecosystem management for areas like Dongting Lake Basin, where ecosystems, though severely degraded, are important and fragile, to realize their huge carbon sequestration potential. [ABSTRACT FROM AUTHOR]

Support for the adoption of climate change mitigation measures in low-income regions depends on how such activities contribute to generating household income and gaining confidence from the local community. The planning of mitigation measures or pro-environmental activities need to consider the cost of deployment, customization of activities according to local conditions, and socio-cultural background and perceptions of people. This paper analyses the incentive induced “agroforestry” or “planting trees in farmland” as part of the Carbon Neutral Programme supported by the Government of Kerala in Meenangadi Grama Panchayath, Wayanad district. An increase in tree cover is proposed as a strategy for increasing carbon sequestration. Planting more trees in farmland (except grain cultivated areas) along with crops, according to farmers, may reduce crop yield and discourage farmers’ participation. The Government of Kerala put forward the concept of a tree banking/tree incentive program to attract farmers to expand tree cover. A survey was conducted among 100 individuals from the Meenangadi Grama Panchayath to assess the perceptions and concerns of farmers about the proposed “Agroforestry”/Tree Banking program. The sample size was chosen from the population assuming a 9.98% error tolerance. Tree Banking Programme designed to encourage farmers to plant trees has gained public interest, and the study also documented the factors influencing the willingness of farmers for planting trees. The study revealed that the majority of the individuals (93% of the survey participants) residing in the region are interested in supporting the activities for climate change mitigation. Financial incentives announced under tree banking generated interest among farmers. 89% of the survey participants consider the incentive scheme to be an attractive option, as it can compensate for the short-term loss in crop productivity. However, farmers were very selective in choosing the tree species to be planted on their farms. Incentivization helps to make sure that a large proportion of the planted saplings will grow into mature trees. Overall, it can be concluded that afforestation in the form of agroforestry could be potentially attractive to the farmers and contribute towards achieving carbon neutrality for tropical agricultural areas.

• Implementation costs are a more relevant constraint to afforestation than opportunity costs. • Financial incentives for afforestation are constrained by market access and market prices. • Carbon-neutral and food multi-oriented land policies need further exploration. • Collaboration among global carbon markets can enhance CO 2 removal efficiency. Afforestation is a promising nature-based climate solution for mitigating climate change, but it is subject to a complex web of biophysical, cost-benefit, market, and policy processes. Although its biophysical feasibility has been established, the cost, market, and policy constraints that affect climate change mitigation through afforestation are still unclear. Here, we estimate such cost, market, and policy constraints on the basis of biophysical feasibility. Our findings reveal that implementation costs are a more relevant constraint than opportunity costs on mitigating climate change through afforestation. The China Certified Emission Reduction market currently provides only a 0.308 % incentive for climate change mitigation through afforestation, due to market access constraints. The current market prices of China Certified Emission Reduction, China Carbon Emissions Trading Exchange, and Nature Based Carbon Offset in Voluntary Carbon Market constrain 88.15 %, 87.95 %, and 85.75 % of CO 2 removal actions through afforestation, compared to the carbon price scenario (US$62.97 tCO 2 -1) of the EU Emissions Trading System. Moreover, land policy under the scenarios of prohibiting conversion of cultivated land to forest and forest restoration in degraded areas exhibit 8.87–29.59 % and 65.16–74.10 % constraints, respectively, on mitigating climate change through afforestation compared to land-use freedom conversion scenarios from 2020 to 2060. Thus, enhancing the incentive price of CO 2 removal, addressing the market access barrier, strengthening cooperation between global carbon markets, and exploring carbon–neutral and food multi-oriented land policies can be valuable sources of mitigation efforts over the next 40 years. [ABSTRACT FROM AUTHOR]

The article presents a study which explores the escalating carbon emissions from North American boreal forest wildfires and the climate mitigation potential of fire management. It characterize the magnitude of recent and projected gross and net boreal North American wildfire carbon dioxide emissions, evaluate fire management as an emissions reduction strategy, and quantify the associated costs.