Effect of water redistribution by two distinct saprotrophic fungi on carbon mineralization and nitrogen translocation in dry soil

Hydraulic redistribution (HR) of water from wet to dry soil compartments by non-differentiated mycelium was recently shown for the saprotrophic fungus Agaricus bisporus. The redistributed water triggered the carbon (C) mineralization in the dry soil. The potential of other saprotrophic fungal species and their mycelia networks for HR in soils is unknown. Here, we tested the potential for HR of the mycelial cord forming species Schizophyllum commune, compared it to capillary water transport in a sandy soil and assessed the impact of HR on C mineralization and enzyme activities in mesocosm experiments with dry and wet soil compartments using labeled water (H-2) and labeled organic substrate (C-13, N-15). Further, we determined nitrogen (N) translocation between the soil compartments by the mycelium of S. commune and A. bisporus. The flow velocity of redistributed water in single hyphae of S. commune was about 0.43 cm min(-1) which is 1.5-2 times higher than in hyphae of A. bisporus, suggesting that cords enhance fungal HR. The amount of redistributed water was similar to capillary transport in the sterile sandy soil. Despite greater potential for HR, S. commune only slightly increased C mineralization and enzyme activity in the dry soil within 7 days. S. commune translocated N towards the organic substrate in the dry soil and used it for hyphal growth whereas A. bisporus redistributed N within the mycelial network towards the wet soil. Our results suggest that fungal hyphae have the potential to overcome capillary barriers between dry and wet soil compartments via HR and that the impact of fungal HR on C mineralization and N translocation is related to the foraging strategy and the resource usage of the fungus species. (C) 2016 Elsevier Ltd. All rights reserved.