MYCORRHIZAS IN NATURAL ECOSYSTEMS

There is now ample evidence to support the common assertion that most plants in natural ecosystems have mycorrhizal associations. Information about the worldwide distribution of plants with different types of mycorrhizal associations is used to establish correlations with the major climatic factors (water, temperature) which regulate the distribution of plants, as well as more localized edaphic conditions. Ecological implications of mycorrhizal associations in natural ecosystems and the role of soil or environmental factors, mycorrhizal fungus characteristics or host plant properties alone or in combination are considered. Factors which can influence the occurrence and effectiveness of mycorrhizal associations include (i) root properties (ii) edaphic or climatic factors (iii) soil complex ecological topics (involving, the environment, plants and mycorrhizal fungi) that are discussed include (i) mycorrhizal phenology, (ii) factors responsible for varying degrees of mycorrhizal dependency in host plants, (iii) the role of mycorrhizal hyphae in soil (iv) nutrient competition involving mycorrhizal and non-mycorrhizal plants and (v) mycorrhizal interactions involving pollution and other stresses, the rhizosphere, soil properties and allelopathy. The population ecology of mycorrhizal fungi and the influence of their associations on plant population ecology are also considered. © 1991, Academic Press Limited.