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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]

In recent years, research on carbon dioxide removal (CDR) has significantly increased. Numerous studies have analyzed demonstration projects, outlined scenarios, modeled pathways, or focused on CDR's national or international governance. However, regional case studies investigating the dynamics that may facilitate or impede the broader adoption of CDR methods in spatially explicit settings are critically absent. Understanding implementation contexts on the ground is vital, and comparing them across different removal methods is essential for effectively scaling up CDR. This paper aims to address this research gap by comparatively examining the development of biomass-based CDR in three regions of Germany. Taking an exploratory approach, we conducted surveys in these regions to gain insight into stakeholder perceptions of the following six CDR methods: forest management, agriculture and soil carbon, long-lasting building materials, rewetting of peatlands and paludiculture, biochar, and bioenergy with carbon capture and storage. In this article, we present the results of the stakeholder survey, which offers multiple perspectives that can shape future studies of regional implementation and yield policy-relevant guidance. Although our research primarily focuses on the regional level in Germany, it sheds light on various conflicts, uncertainties, and potentials that are likely to be relevant for the rollout of CDR in other countries. By examining these aspects, we contribute to the broader discourse on CDR and its potential implementation. [ABSTRACT FROM AUTHOR]

In recent years, research on carbon dioxide removal (CDR) has significantly increased. Numerous studies have analyzed demonstration projects, outlined scenarios, modeled pathways, or focused on CDR’s national or international governance. However, regional case studies investigating the dynamics that may facilitate or impede the broader adoption of CDR methods in spatially explicit settings are critically absent. Understanding implementation contexts on the ground is vital, and comparing them across different removal methods is essential for effectively scaling up CDR. This paper aims to address this research gap by comparatively examining the development of biomass-based CDR in three regions of Germany. Taking an exploratory approach, we conducted surveys in these regions to gain insight into stakeholder perceptions of the following six CDR methods: forest management, agriculture and soil carbon, long-lasting building materials, rewetting of peatlands and paludiculture, biochar, and bioenergy with carbon capture and storage. In this article, we present the results of the stakeholder survey, which offers multiple perspectives that can shape future studies of regional implementation and yield policy-relevant guidance. Although our research primarily focuses on the regional level in Germany, it sheds light on various conflicts, uncertainties, and potentials that are likely to be relevant for the rollout of CDR in other countries. By examining these aspects, we contribute to the broader discourse on CDR and its potential implementation.

• The policy discourse on negative emissions is rapidly gaining momentum. • A discursive shift towards deployment is evident. • BECCS and afforestation are the most prominent land-based technologies in the discourse. • Most actors are based in the Global North; 61% refer to Global South in statements. • 116 policy documents from 2013 to 2019 were manually coded and analyzed. Negative emissions are increasingly seen as a policy option to limit climate change. However, the most readily available technologies that could deliver negative emissions require, if deployed at scale, large amounts of land, with huge risks for livelihoods and the environment. This land is often assumed to be in the Global South. This article analyzes the nascent policy discourse on negative emissions by assessing 116 policy documents by 97 organizations with a focus on land-based technologies (afforestation and reforestation, bioenergy with carbon capture and storage, biochar, soil carbon sequestration). We conclude that this policy discourse is largely centered in the Global North (mostly in the United States, the United Kingdom, and Germany), with only five organizations directly linked to the Global South. 61% of the organizations in our sample, however, somehow refer to the Global South in their contributions, with nongovernmental organizations being most strongly focused on the role of the Global South and in particular the risks for vulnerable countries. While the earlier policy discourse on negative emissions was linked to a more general "geoengineering" discourse, this link has loosened in the last years. Overall, in the documents that we studied, negative emissions technologies seem to become more accepted, and parts of the discourse shift towards deployment. Bioenergy with carbon capture and storage seems more often associated with risks if compared to other land-based negative emissions technologies, especially with a view to the Global South. [ABSTRACT FROM AUTHOR]

Anthropogenic emissions of carbon dioxide (CO2) contribute to global warming. Limiting temperature rise requires negative emission techniques to retract the emitted CO2 from the atmosphere. Through photosynthesis, ecosystems naturally sequester and store carbon. Enhancing these processes forms the basis of biological sequestration strategies. Ecosystems are a sink of atmospheric CO2 and significantly impact the global carbon cycle. The fixed carbon is converted into biomass, a portion of which enters the soil carbon pool and can be sequestered for millennia. The formation of stable soil organic carbon (SOC) depends on land use, management practices, and the use of amendments. Employing best management practices and carbon boosting approaches such as conservation agriculture, agroforestry, biochar, afforestation, and restoration of wetlands can improve SOC stocks and create a positive soil carbon budget, especially in degraded ecosystems. . Carbon fixation by plants and microbes is fundamental to biological sequestration. Regulating the properties and expression of the enzymes involved and introducing novel pathways for carbon capture can enhance carbon fixation efficiency and positively affect yield. This review discusses biological carbon sequestration strategies highlighting the recent findings in the effects and potential of soil carbon boosting approaches in carbon mitigation and the prospects of genetic engineering in enhancing carbon fixation.

Vachellia nilotica (L.) P.J.H. Hurther & Mabb. and Dalbergia sissoo Roxb. are two of the most important multipurpose agroforestry tree species of the Indian sub-continent, but their growth in saline soils is greatly reduced. Recently, organic amendments have showed the potential to increase plant growth in salt-affected soils; however, the influence of using these amendments for growing the above-mentioned tree species under saline conditions is not yet quantified. Therefore, an experiment was devised to analyze the interactive effects of organic amendments in saline soils on the growth of V. nilotica and D. sissoo. Under controlled conditions, a pot experiment was conducted in sandy loam saline soils (EC = 20.5 dSm−1). Organic amendments from four diverse sources: farmyard manure (FYM), poultry manure (PM), slurry (SL), and farmyard manure biochar (FYMB) were employed in this study. At the harvesting time, data regarding morphological, physiological, ionic, and biochemical parameters were obtained. The current study results indicated that both tree species reacted differently, but positively, to diverse applied amendments. The maximum increment in total above-ground biomass, total below-ground biomass, and shoot length for V. nilotica (163.8%, 116.3%, and 68.2%, respectively) was observed in FYM amended soils, while the maximum increment for D. sissoo (128%, 86%, and 107%, respectively) was observed in FYMB amended soils, as compared to control. Minimum plant growth of both species was observed in untreated soils (saline soils). Likewise, the maximum potassium ion and minimum sodium ion concentrations were present in the root and shoots of plants (both species) treated with FYMB. The use of organic amendments resulted in decreased concentrations of malondialdehyde and hydrogen peroxide, and increased concentrations of antioxidant enzymes such as SOD, POD, and CAT. Moreover, higher photosynthetic rates and stomatal conductance were observed in the plants grown in amended soils. The findings of this study can be used to include the above-mentioned high-value tree species for future afforestation programs under saline conditions. [ABSTRACT FROM AUTHOR]

Vachellia nilotica (L.) P.J.H. Hurther & Mabb. and Dalbergia sissoo Roxb. are two of the most important multipurpose agroforestry tree species of the Indian sub-continent, but their growth in saline soils is greatly reduced. Recently, organic amendments have showed the potential to increase plant growth in salt-affected soils; however, the influence of using these amendments for growing the above-mentioned tree species under saline conditions is not yet quantified. Therefore, an experiment was devised to analyze the interactive effects of organic amendments in saline soils on the growth of V. nilotica and D. sissoo. Under controlled conditions, a pot experiment was conducted in sandy loam saline soils (EC = 20.5 dSm−1). Organic amendments from four diverse sources: farmyard manure (FYM), poultry manure (PM), slurry (SL), and farmyard manure biochar (FYMB) were employed in this study. At the harvesting time, data regarding morphological, physiological, ionic, and biochemical parameters were obtained. The current study results indicated that both tree species reacted differently, but positively, to diverse applied amendments. The maximum increment in total above-ground biomass, total below-ground biomass, and shoot length for V. nilotica (163.8%, 116.3%, and 68.2%, respectively) was observed in FYM amended soils, while the maximum increment for D. sissoo (128%, 86%, and 107%, respectively) was observed in FYMB amended soils, as compared to control. Minimum plant growth of both species was observed in untreated soils (saline soils). Likewise, the maximum potassium ion and minimum sodium ion concentrations were present in the root and shoots of plants (both species) treated with FYMB. The use of organic amendments resulted in decreased concentrations of malondialdehyde and hydrogen peroxide, and increased concentrations of antioxidant enzymes such as SOD, POD, and CAT. Moreover, higher photosynthetic rates and stomatal conductance were observed in the plants grown in amended soils. The findings of this study can be used to include the above-mentioned high-value tree species for future afforestation programs under saline conditions.