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Salinity is a global issue and Eucalyptus camaldulensis Dehnh. is one of the most planted agroforestry tree species on saline soils in Pakistan. Organic amendments are reported to ameliorate plant growth in saline sodic soils. This study was designed to examine the effects of different organic amendments on the growth of E. camaldulensis grown in saline soil. A pot experiment was performed and seedlings of E. camaldulensis were grown in soil having pH (8.5) and EC(e) 20.5dS/m. Four types of organic amendments were used: farmyard manure, poultry manure, slurry and biochar. The maximum plant total biomass (132.12 g), root length (24.67 cm) and shoot length (174.33 cm) were recorded in the plants grown in soils amended with farmyard manure. The minimum plant total biomass (36.05 g), root length (9.44 cm) and shoot length (68.0 cm) were found in plants without any amendment. Plants treated with farmyard manure and biochar showed the best results for chlorophyll contents, photosynthetic rate and stomatal conductance. Sodium contents in the shoots and roots of plants treated with organic amendments were decreased whereas potassium contents were increased. Maximum sodium contents were found in the shoot (5.70 mg/g DW) and root (7.71 mg/g DW) of un-amended plants, whereas, maximum potassium contents were in the shoots (7.81 mg/g DW) and roots 6.33 mg/g DW) of plants treated with biochar. Biochar was found to be best amendment to improve physicochemical characteristics of soil by improving organic matter (%) and saturation (%) as well as decreasing EC and SAR values of saline soils. Findings of this experiment suggested that organic amendments are useful in enhancing the early stage growth of E. camaldulensis in saline soils. [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]

Land-management options for greenhouse gas removal (GGR) include afforestation or reforestation (AR), wetland restoration, soil carbon sequestration (SCS), biochar, terrestrial enhanced weathering (TEW), and bioenergy with carbon capture and storage (BECCS). We assess the opportunities and risks associated with these options through the lens of their potential impacts on ecosystem services (Nature's Contributions to People; NCPs) and the United Nations Sustainable Development Goals (SDGs). We find that all land-based GGR options contribute positively to at least some NCPs and SDGs. Wetland restoration and SCS almost exclusively deliver positive impacts. A few GGR options, such as afforestation, BECCS, and biochar potentially impact negatively some NCPs and SDGs, particularly when implemented at scale, largely through competition for land. For those that present risks or are least understood, more research is required, and demonstration projects need to proceed with caution. For options that present low risks and provide cobenefits, implementation can proceed more rapidly following no-regrets principles. [ABSTRACT FROM AUTHOR]