Fine-root Production and Turnover in a Willow Plantation Estimated by Different Calculation Methods

Abstract Fine-root production and turnover were estimated in a short-rotation stand of basket willow (Salix viminalis L.) in central Sweden. Different calculation methods, based on soil coring, or combinations of soil coring and minirhizotron technique, were used. Fine-root biomass production and mortality in the 0–50 cm soil horizon were estimated at 900–7200 kg ha−1 yr−1 and 500–6800 kg ha−1 yr−1, respectively, depending on the method used. Corresponding values for production and mortality of fine-root length per unit soil volume were 160–1600 dm dm−3 yr−1 and 40–1500 dm dm−3 yr−1, respectively. Methods based on soil coring alone gave the lowest estimates, and probably underestimated production and mortality, since both processes to a high degree occurred simultaneously in the willow plantation. Thus, this study emphasizes the necessity to separate the processes of growth and decay where high fine-root turnover occurs.