Research Progress of Plant Available Carbon in the Earth's Carbon Cycle Xiang-ping Sun, Hua-jiao Qiu, Wang Zhuo, Cai-sheng Qiu, Guo-qian Zhong, Xin-ling Zhao, Zhi-min Zhao, Song-hua Long and Wook Won Sung E3S Web Conf., 617 (2025) 01008 Published online: 21 February 2025 DOI: 10.1051/e3sconf/202561701008