Nutrient transfer from soil nematodes to plants: a direct pathway providedby the mycorrhizal mycelial network

A pathway for the transfer of nutrients from dead nematodes to mycorrhizal plants is described for the first time. Plants of Betula pendula were grown in transparent microcosms in the mycorrhizal (M) or non-mycorrhizal (NM) c ondition, either with or without nematode necromass of known nitrogen (N) a nd phosphorus (P) contents as the major potential source of these elements. Plants colonized by the mycorrhizal fungus Paxillus involutus produced gre ater yields and had larger N and P contents in the presence of nematodes th an did their NM counterparts. The symbiotic systems were shown to exploit t he N and P originally contained in necromass more effectively, and to trans fer the nutrients to the plants in quantities approximately double those se en in NM systems. Even so, NM plants obtained sufficient N and P from dead nematodes to enable some enhancement of growth. Our observations confirm th at mycorrhizal fungi provide the potential for the recycling of nutrients c ontained in this quantitatively important component of the soil mesofauna a nd demonstrate that the symbiotic pathway is considerably more effective th an that provided by saprotrophs alone. The consequences of this nutrient tr ansfer pathway for nutrient recycling in temperate forest ecosystems are co nsidered.