Mycorrhizae of alpine fell-field communities on soils derived from crystalline and calcareous parent materials

Abstract

The degree of vesicular–arbuscular mycorrhizal root colonization of alpine fell-field plants was measured at six sites in the northern Rocky Mountains of Montana and Wyoming. Soils derived from calcareous or acidic crystalline parent materials were analyzed for chemical and physical properties and vesicular–arbuscular mycorrhizal fungal propagule density. Soils associated with calcareous parent materials had finer texture, higher pH, and higher levels of calcium, sodium, and silicon. Viable vesicular–arbuscular mycorrhizal propagule density was positively correlated with plant canopy cover. Typical vesicular–arbuscular mycorrhizal colonization occurred in 84% of the species examined. Vesicular–arbuscular mycorrhizal root colonization was significantly greater on soils derived from calcareous parent materials. Alkaline pH and high levels of calcium associated with calcareous soils may result in these soils being functionally more phosphorus deficient than are crystalline soils. Phosphorus deficiency may partially explain the higher levels of vesicular–arbuscular mycorrhizal colonization observed.