Abstract: Plants play a key role in regulating the balance of atmospheric CO₂ concentrations, improving carbon sequestration capacity and ecosystem carbon stocks, and contributing to the mitigation of global warming. It is therefore of great significance to further understand the factors affecting the net carbon sequestration capacity of plants in order to achieve the targets of carbon peak and carbon neutralization in China. We summarized the recent progresses in carbon fixation pathways in photosynthesis, carbon release processes through litter decomposition, and factors (CO₂ concentration, temperature, water content, litter addition and removal) affecting carbon sequestration and carbon release through CO₂ and CH₄ emissions. The results showed that there was a threshold for the promotion of water, temperature, and CO₂ concentration on plant carbon sequestration and the promotion of water and temperature on the CO₂ emission from litter decomposition. When the threshold exceeds a certain range, an inhibitory effect exists on the aforementioned process. Litter removal is beneficial to reducing CO₂ emission, but the response of CH₄ emission through litter decomposition to the above environmental factors has been inconclusive. We propose to strengthen studies on the carbon sequestration ability of plants in different stages of life cycles by the combined action of multiple environmental factors; and on carbon emission mechanisms of tree residues, belowground litter, root exudates, and their responses to environmental factors, which will provide a reference for improving plant carbon sequestration and carbon neutrality.

Key words: photosynthetic carbon sequestration, litter carbon emission, influencing factor, net carbon sequestration capacity, carbon neutralization.