ARBUSCULAR MYCORRHIZAL FUNGI INDUCED ALTERATION TO ROOT LONGEVITY OF POPLAR

Root longevity is an important element determining the fluxes of nutri ents and carbon within terrestrial ecosystems. The effect of colonisat ion by an arbuscular mycorrhizal (AM) fungus on root longevity of popl ar was determined using a minirhizotron camera to make direct observat ion of roots in situ in conjunction with image analysis. Significant i nfluences of colonisation on the longevity of roots were observed with most colonised roots surviving for a shorter period than non-colonise d roots only 16% of colonised roots survived for longer than 49 days c ompared to 49% of non-colonised roots. After 21 days approximately 5 t imes as many colonised as non-colonised roots had died. Possible mecha nisms are discussed.