TABLE 5.16 Seedling Plant Height and Survival of Three Tree Species in a Tree Nursery in Which the Soil Surface was Left Bare or Had been Covered with the Foliose Lichen Cladonia alpestris Collected from a Surrounding Forest

Pinus sylvestris 22.2 93 25.8 100

Picea abies 21.4 84 31.2 100

Betula verrucosa 105.0 70 108.0 67

Source: Data from Brown and Mikola (1974).

onto new land. We have seen in this chapter how the presence of mycorrhizal inocula carried into newly colonized areas benefits the plants in terms of nutrient and water acquisition. The patchy distribution of these pockets of inoculum, together with patchy distributions of suitable rooting media, lead to spatial variability in the benefits derived by the plant from mycorrhizal associations. In very resource rich areas, it would seem that nonmycorrhizal ruderals are capable of surviving. It is the combination of this heterogeneity in the environment, patchily distributed beneficial fungi, and the increased growth and fitness of individuals and individual species in this mosaic that gives rise to the plant community structure that develops.