THE EFFECT OF SOIL DISTURBANCE ON VESICULAR ARBUSCULAR MYCORRHIZAL FUNGI IN SOILS FROM DIFFERENT VEGETATION TYPES

The infectivity of vesicular-arbuscular (VA) mycorrhizal fungi in three soils from different vegetation types was compared before and after disturbance. The relative quantities of infective propagules in the disturbed soils were estimated by an infectivity test after the soils were diluted. Spore numbers and mycorrhizal roots were also quantified in each soil. The mycorrhizal colonization of clover roots in the infectivity test was not decreased after soil from an annual pasture had been disturbed. In contrast, in both a forest soil and a heathland soil, the percentage root length colonized of test plants was almost halved if the soils had been disturbed. In the pasture soil up to 10 times or 25 times more propagules survived disturbance than in the forest soil or the heathland soil respectively. The large number of propagules may allow the VA mycorrhizal fungi in the pasture soil to maintain maximum infectivity after soil disturbance.