SPATIOTEMPORAL PATTERNS IN ECTOMYCORRHIZAL POPULATIONS

To understand the functioning and ecological roles of ectomycorrhizal fungi in natural ecosystems, it is necessary to have adequate knowledge of the spatial distribution of individual mycelial systems in populations and communities and how this distribution may persist or vary with time. However, this issue has attracted relatively little attention until recently. Moreover, the limited information available is mostly based on the distribution of sporocarps, which is at best an unreliable indicator of the location and activity of mycelia. More useful information can be obtained using somatic and sexual incompatibility tests, as well as molecular markers to trace the distribution of individual genets over a range of spatial and temporal scales. For example, it has been possible using this approach to demonstrate that while young populations tend to consist of numerous small mycelia, individuals in older populations tend to be fewer and larger but heterogeneous in scale. It has also been possible to verify the persistence over several years of mycorrhizal mycelial individuals. Such findings represent only the first step in the study of the spatiotemporal dynamics of ectomycorrhizal fungi, which promises to be a rich and important field for future research. Concepts concerning the process and mechanisms likely to affect distribution patterns are discussed.