ARBUSCULAR MYCORRHIZAE OF ACER-SACCHARUM IN DIFFERENT SOIL TYPES

Differences in propagule levels and in the colonization of Acer saccharum feeder roots by arbuscular mycorrhizal fungi in maple forests distributed across three different soil types (brunisols, luvisols, podzols) were investigated. All forest stands were located in southern Ontario. Acer saccharum was the dominant tree species, making up at least 75% of all trees. Results show that arbuscular mycorrhizae can dominate in different soil types, even in podzolic soils with moder-type humus, which typically support ectomycorrhizal associations. In fact, total hyphal colonization of A. saccharum roots and the capacity of the soil to initiate infection units were highest in the podzolic soils compared with those in brunisolic and luvisolic soils. In brunisolic soils, the roots exhibited high arbuscular colonization, low coil colonization, low vesicular colonization, and relatively moderate sporulation levels. In luvisolic soils, colonization was similar to that of brunisols; however, spore densities were lower. Roots in podzolic soils showed very different trends, with a low occurrence of arbuscules, high levels of hyphal coils and vesicles, and much higher spore densities. Soil type can account for much of the variability in arbuscular mycorrhizal structure and functioning that occurs among different locations.