ASHS 2024 Conference

In October 2020, the Republic of Korea set a landmark goal to achieve net zero emissions by 2050. However, the national greenhouse gas emission statistics did not account for carbon absorption by agricultural lands, including orchards, due to the absence of adequate calculation systems and data. Recognizing the significant role of photosynthesis in fruit trees like Citrus in carbon sequestration and climate change mitigation, this study aims to address this gap. We focused on developing allometric equations for estimating biomass and carbon stocks of citrus trees, particularly in orchards across Korea, with a case study on Jeju Island, a principal citrus cultivation area. Measurements of height, crown width, and the diameter of rootstock and trunks were conducted, observing an increase with tree age, though trunk diameter showed considerable variability. The study encompassed trees aged 5–45 years of the Satsuma Mandarin (Citrus unshiu Marc. cv. Miyagawa), a major citrus cultivar cultivated in Korea. Components including leaves, branches, trunks, and roots were harvested, dissected, fresh weighed, and oven-dried to develop dry to fresh weight ratios for dry biomass calculation. Allometric equations with trunk diameter as the sole independent variable were formulated for the Satsuma Mandarin tree. Furthermore, the total carbon content for trees aged 5–45 years was assessed through direct and destructive harvesting, revealing a carbon content range of 44.13 to 46.85% across different tree organs, with root carbon content increasing with age. This comprehensive study provides crucial insights into the biomass and potential carbon fixation capabilities of citrus trees, contributing significantly towards the accuracy of national carbon stock estimations. This work was carried out with the support of the Research Program for the National Institute of Horticultural