Sustained Biomass Carbon Sequestration by China’s Forests from 2010 to 2050

Forest carbon storage and sink estimates under different management scenarios in China from 2020 to 2100

Forests play a crucial role in mitigating climate change through carbon storage and sequestration, though environmental change drivers and management scenarios are likely to influence these contributions across multiple spatial and temporal scales. In this study, we employed three tree growth models-the Richard, Hossfeld, and Korf models-that account for the biological characteristics of trees, alongside national forest inventory (NFI) datasets from 1994 to 2018, to evaluate the carbon sink potential of existing forests and afforested regions in China from 2020 to 2100, assuming multiple afforestation and forest management scenarios. Our results indicate that the Richard, Hossfeld, and Korf models provided a good fit for 26 types of vegetation biomass in both natural and planted Chinese forests. These models estimate that in 2020, carbon stocks in existing Chinese forests are 7.62 ± 0.05 Pg C, equivalent to an average of 44.32 ± 0.32 Mg C/ ha. Our predictions then indicate this total forest carbon stock is expected to increase to 15.51 ± 0.99 Pg C (or 72.26 ± 4.6 Mg C/ha) in 2060, and further to 19.59 ± 1.36 Pg C (or 91.31 ± 6.33 Mg C/ha) in 2100. We also show that plantation management measures, namely tree species replacement, would increase carbon sinks to 0.09 Pg C/ year (contributing 38.9 %) in 2030 and 0.06 Pg C/ year (contributing 32.4 %) in 2060. Afforestation using tree species with strong carbon sink capacity in existing plantations would further significantly increase carbon sinks from 0.02 Pg C/year (contributing 10.3 %) in 2030 to 0.06 Pg C/year (contributing 28.2 %) in 2060. Our results quantify the role plantation management plays in providing a strong increase in forest carbon sequestration at national scales, pointing to afforestation with native tree species with high carbon sequestration as key in achieving China's 2060 carbon neutrality target.

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.

Planted forest is catching up with natural forest in China in terms of carbon density and carbon storage

Over the last several decades, China has taken multiple measures for afforestation and natural forest protection, including setting the goal of carbon neutrality by the middle of 21th century. In order to support the practice of relevant policies from the scientific perspective, it is essential to precisely estimate the carbon storage of arbor forest, as it plays an important role in the carbon cycle of ecosystems. In this study, we first used the latest four phases of national forest inventory data to investigate the variation of carbon storage for both natural and planted arbor forest in China during the covered period (1999-2018). Then we used machine leaning methods to simulate the carbon density based on various kinds of environmental factors and analyzed the contribution of each influencing factor. Our results demonstrate that the total carbon storage for arbor forest in China kept increasing over the last two decades, but this increment was mainly brought about by the continuous expansion of forest land. The gap of carbon sequestration between natural forest and planted forest showed a significant trend of reduction. Additionally, tree age was identified as the dominant factor for influencing the spatiotemporal variation of carbon density among all the independent variables while the impact of climatic factor was limited. Therefore, the future improvement of carbon sequestration of arbor forest in should mainly rely on additional projects of afforestation, reforestation, green space conservation and reduction of emissions in China. Conclusions of this study have important implications for policy makers and other stakeholders to evaluate the previous achievement of environmental projects and can also help to set future plans and finally realize the goals of carbon neutrality.

Estimating Carbon Sequestration Potential of Forest and Its Influencing Factors at Fine Spatial-Scales: A Case Study of Lushan City in Southern China

Accurate prediction of forest carbon sequestration potential requires a comprehensive understanding of tree growth relationships. However, the studies for estimating carbon sequestration potential concerning tree growth relationships at fine spatial-scales have been limited. In this paper, we assessed the current carbon stock and predicted sequestration potential of Lushan City, where a region has rich vegetation types in southern China, by introducing parameters of diameter at breast height (DBH) and tree height in the method of coupling biomass expansion factor (BEF) and tree growth equation. The partial least squares regression (PLSR) was used to explore the role of combined condition factors (e.g., site, stand, climate) on carbon sequestration potential. The results showed that (1) in 2019, the total carbon stock of trees in Lushan City was 9.22 × 10⁵ t, and the overall spatial distribution exhibited a decreasing tendency from northwest to south-central, and the carbon density increased with elevation; (2) By 2070, the carbon density of forest in Lushan City will reach a relatively stable state, and the carbon stock will continue to rise to 2.15 × 10⁶ t, which is 2.33 times of the current level, indicating that Lushan forest will continue to serve as a carbon sink for the next fifty years; (3) Excluding the effect of tree growth, regional forest carbon sequestration potential was significantly influenced on site characteristics, which achieved the highest Variable Importance in Projection (VIP) value (2.19) for slope direction. Our study provided a better understanding of the relationships between forest growth and carbon sequestration potential at fine spatial-scales. The results regarding the condition factors and how their combination characteristics affect the potential for carbon sequestration could provide crucial insights for Chinese carbon policy and global carbon neutrality goals.

Current and Future Potential of Shellfish and Algae Mariculture Carbon Sinks in China

Shellfish and algae mariculture make up an important part of the marine fishery carbon sink. Carbon sink research is necessary to ensure China achieves its goal of carbon neutrality. This study used the material quality assessment method to estimate the carbon sink capacity of shellfish and algae. Product value, carbon storage value, and oxygen release value were used to calculate the economic value of shellfish and algae carbon sequestration. The results showed that the annual average shellfish and algae carbon sink in China was 1.10 million tons from 2003 to 2019, of which shellfish accounted for 91.63%, wherein Crassostreagigas, Ruditapesphilippinarum, and Chlamysfarreri were the main contributors. The annual average economic value of China’s shellfish and algae carbon sequestration was USD 71,303.56 million, and the product value was the main contributor, accounting for 99.11%. The carbon sink conversion ratios of shellfish and algae were 8.37% and 5.20%, respectively, thus making shellfish the aquaculture species with the strongest carbon sink capacity and the greatest carbon sink potential. The estimated growth rate in the shellfish and algae removable carbon sink was 33,900 tons/year in China, but this trend was uncertain. The capacity for carbon sequestration and exchange by aquaculture can be improved by expanding breeding space, promoting multi-level comprehensive breeding modes, and marine artificial upwelling projects.

Is It Possible for Poland to Achieve the Policy Goal of 33% Forest Cover by Mid-Century?

The aim of the present paper is to discuss the problems with attempts to increase forest area in Poland (with a focusing on afforestation in the last 30 years), to analyse the discrepancy between the afforested area and the recorded increase in forest area, and to identify solutions that could enable Poland to achieve the policy goal of 33% forest cover by 2050. The study is based on available official documents, statistical data, and the existing literature. It presents the results of a postal survey of key institutional actors involved in afforestation in Poland on the factors hindering the implementation of afforestation on private land. The study shows that the main factors influencing the collapse of afforestation are long-term, and it is unlikely that this trend will be reversed in the coming years. However, it appears possible to take steps to convert forested agricultural lands that meet national criteria for recognition as forest to forest. The urgent need to protect biodiversity and improve environmental quality in the face of climate change makes it necessary to develop and implement a new program to increase forest area and to provide coherent tools to support the conversion of forested agricultural land to forest.

Valuing Carbon Sequestration to Finance Afforestation Projects in China

Afforestation programs have huge potential to store carbon, thereby contributing to mitigate climate change. However, the voluntary acceptance by landowners crucially depends on their economic outcome. We (i) assess the carbon sequestration potential of afforestation projects in various Chinese regions by comparing different tree species, project durations and regional particularities, (ii) analyze the costs and benefits of tree species used for timber and fruit production as well as bamboo, and (iii) compare them with alternative crops under different climatic and economic conditions. Finally, we calculate the minimum compensation required by farmers to convert cropland to forests assuming a joint production of timber or fruits and carbon sequestration. No compensation is needed when cropland with relatively low revenues is to be converted. In contrast, compensation payments must be high for converting land used for cash crops, such as sugarcane. For fruit trees, the amount of carbon sequestered is low, but selling fruits and nuts is quite profitable. Consequently, in most cases there is no compensation needed. The minimum price per carbon credit decreases with increasing project duration because more carbon is stored per hectare, and in consequence, the required payments per credit are lower. This does not hold for fast-growing trees like eucalyptus and poplar, for which the minimum price increases with extended project duration. Bamboo shows a high carbon sequestration potential, and becomes economically more attractive by including carbon revenues. Carbon credits can often compensate the opportunity costs of alternative land uses, except for afforestation on highly productive cropland. We demonstrate that the economic attractiveness of afforestation projects is strongly context dependent and varies substantially across regions. The findings can contribute to the cost-efficient design of carbon sequestration projects. The methodology can be applied to other regions in the developing world.