Respiratory activity of intact and excised ectomycorrhizal mycelial systems growing in unsterilized soil

Abstract:
Ectomycorrhizal mycelial systems were grown in unsterile soil using specially designed growth chambers, and the respiratory activity of the mycelium was measured before and after its excision from the host roots. Approximately 30% of the total respiration in the intact system was attributable to the mycorrhizal mycelium in the soil. Severance of mycelial connections at the roots lead to a greater than 50% decrease in respiration rate within 24 h. This decline was much more rapid than that of root respiration rate which occurred when the shoot was excised from the intact system. The implications of these findings for the carbon balance and microbial ecology of forest systems are discussed.