A 13C method of estimation of carbon allocation to roots in a young chestnut coppice

Abstract A method is described in which 1 year‐old chestnut coppice was fed in situ with air highly enriched in 13 CO 2 (23%). After 3 days, 13 C concentration increases in shoots were measured by mass spectrometry. Respiratory losses between 13 C feeding and harvest were estimated using two different methods: (i) a model involving the temperature response of respiration and (ii) direct measurement of 13 C content of the CO 2 respired by the shoots during the night. Carbon allocation to roots was deduced by subtracting from the given amount of 13 C, the amount remaining in shoots and the 13 C respired by the shoots. The method was tested twice during the growing season. Very little carbon was allocated to roots in late July, but over 80% of assimilated 13 C went to roots at the end of September. Despite some approximations in the 13 C respiratory losses estimations, the method allowed evaluation of carbon allocation to roots with an error of about 5%.