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Dr. Chao Yue collaborated with Dr. Shilong Piao from Peking University to publish in PNAS on building a progressive forestation roadmap to support carbon neutrality in China

Update time:2023-10-13

Afforestation and reforestation have been proposed as natural climate solutions for enhancing land carbon sink and climate mitigation. Previous research has primarily focused on the carbon sequestration of mature forests in forestation areas, neglecting the contribution of a short-term to medium-term forestation roadmap to support carbon neutrality. In addition, forestation projects with maladapted species have been reported to risk a low survival rate, which in turn threatens the stability of forest carbon stock, highlighting the need to select appropriate forest types or forest species in forestation projects. These deficiencies resulted in an unclear forestation roadmap to support carbon neutrality in China, further raising feasibility concerns about the government targets and milestones.

Dr. Chao Yue from Institute of Soil and Water Conservation, Northwest A&F University collaborated with Dr. Shilong Piao from Peking University developed an illustrative roadmap for China's forestation strategy to support its carbon neutrality goal and evaluated the associated biophysical carbon sink potential by addressing the three key questions: “where to afforest”, “with what forest species to afforest” and “when to afforest”. For the question of “where” to afforest, their study synthesized multiple datasets of potential forest distribution, existing forest, cropland, and urban distributions to determine the places where forestation is appropriate. For the question of “when” to afforest, their study integrated the government's forest cover targets with the potential forestation area and developed a progressive forestation scenario. For the question of “with what” to afforest, given that the species selection is influenced by “where” and “when” to afforest, they used a species distribution model to predict the environmentally suitable species or forest type out of a total of 15 forest types and further combined the outcome with forest growth models to search for optimal forest species providing the maximum biomass carbon sequestration potential.

Their study revealed an additional 78 Mha suitable for forestation up to the 2060s, a 43% increase of the current forest area. The potential forest area is mainly distributed in the south, northeast and southwest of China, with a small fraction being located in the north, north and northwest of China (Figure 1). Selecting forest species for maximal carbon stock in addition to maximizing local environmental suitability enabled almost a doubling in forest carbon sink potential. Progressive forestation of this area can fix a considerable amount of CO2 and compensate for the carbon sink decline in existing forests (Figure 2). Altogether, the entire forest ecosystem can support a persistent biophysical carbon sink potential of 0.4 Pg C y？1 by 2060 and 0.2 Pg C y？1 by 2100, offsetting 7 to 14% of the current national fossil CO2 emissions (Figure 2).

Figure 1 Potential forestation opportunity in China.

Figure 2 Dynamics of biomass carbon storage and carbon sink of existing and newly established forests under the progressive forestation scenario for 2020 to 2100.

It should be noted that carbon sinks over both the existing and the newly established forests will inevitably diminish in the last few decades of this century when all forestation opportunities are exhausted (Figure 2). To maintain the net zero-carbon emissions state, further reduction of anthropogenic emissions must be required. In other words, our study does by no means preclude the urgent need to reduce greenhouse gas emissions. Instead, the temporal path of forest carbon sink potential should be integrated with the planning of emissions reduction from the energy and industrial sectors, so that the successful implementation of the carbon-neutrality strategy can be secured by respecting the potential boundaries of natural climate solutions. This research hence provides an example of building a forestation roadmap to support climate mitigation policies and the carbon neutrality goal.

Their paper, entitled “Forestation at the right time with the right species can generate persistent carbon benefits in China” was published in the journal “Proceedings of the National Academy of Sciences” (PNAS). (Link: https://doi.org/10.1073/pnas.2304988120). At the same time, PNAS highlighted this research with the title “Carbon benefits of forestation in China” in “In This Issue” (Link: https://doi.org/10.1073/iti4123120). Dr. Chao Yue and Dr. Shilong Piao from Peking University are both the corresponding authors, and PhD candidate Hao Xu from the College of Urban and Environmental Sciences, Peking University, is the first author.