Format: ORAL

Yupei Wei1 2, Juan Guo1 2, Yafang Yin1 2

1 Wood Anatomy and Utilization Department, Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, China 2 Wood Collections (WOODPEDIA), Chinese Academy of Forestry, Beijing 100091, China

Increasing role of forestry has been recognized in carbon (C) neutrality. Carbon fraction (CF) of trees is essential for quantifying forest C stocks and recognizing the global C dynamics. Considerable attention has been paid to CF variations at various levels, with the exception of inter- and intra-growth rings. This hinders comprehension of C uptake dynamics and impedes innovation and development of C sequestration in forest cultivation. Herein, the inter- and intra-growth ring variation of CF inPinus tabuliformis,one of the most important plantation species in the northern part of China, was investigated in this study.Elemental analysis was performed to obtain CF values of the earlywood and latewood in each growth ring of the xylem.Patterns of CF variation at the growth ring level were then evaluated using mixed effect models. The results showed that latewood CF, 50.6%, was significantly higher than earlywood CF, 49.9% (p0.01).In particular, inter-growth ring variations of CF differed between heartwood and sapwood, as well as between juvenile wood and mature wood. CF values decreased nonlinearly with cambium age toward the heartwood or juvenile wood, with estimated least-squares means of 50.4% and 51.8%, respectively. While CF values were almost unaltered in sapwood, but slightly decreased in mature wood, with estimated least-squares means of 50.0% and 50.2%, respectively. It indicates that patterns of CF variation between juvenile wood and mature wood are important to estimate the C stock of P. tabuliformis.Our research provides insights into C gains for forest management and wood utilization. To better understand the impact of forests on global C dynamics, it is necessary to conduct further research on CF values and accurately measure the C stocks they contain. Additionally, it is important to gain a deeper understanding of the patterns, causes, and potential adaptive significance of chemical traits in forests.