Fine roots production and turnover is a significant component of the carbon cycle in forest ecosystems. Fine root survivorship was monitored by minirhizotrons during two successive years in two subtropical evergreen broadleaved forests (Altingia grlilipes, ALG; and, Castanopsis carlesii, CAC) in Wanmulin Natural Reserve, Jian-ou, Fujian province. Root longevity was estimated by the Kaplan-Meier method and differences among single factors, including fine root diameter (d<0.3 mm, 0.30.05). With the increase of root order, mean fine root longevity of ALG and CAC were increased significantly (P<0.01). Mean fine root of ALG's first order and higher order were (267±8) d and (559±32) d, respectively, While CAC's were (247±10) d and (425±41) d. The number of fine root in ALG and CAC was decreased with root order increased. With the addition of number of neighbor root, mean fine root longevity of ALG and CAC were increased significantly (P<0.01). Furthermore, mean fine root longevity of ALG in 00.05). According to the size of impact on root longevity, these factors can be ranked as: root order, season of birth, root diameter, and number of neighbor root. Soil depth had the weakest effect in ALG while had no effect in CAC (P>0.05).
