SPATIOTEMPORAL PATTERNS IN ECTOMYCORRHIZAL POPULATIONS

To understand the functioning and ecological roles of ectomycorrhizal fungi in natural ecosystems, it is necessary to have adequate knowledg e of the spatial distribution of individual mycelial systems in popula tions and communities and how this distribution may persist or vary wi th 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 unreliab le indicator of the location and activity of mycelia. More useful info rmation 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 h as been possible using this approach to demonstrate that while young p opulations tend to consist of numerous small mycelia, individuals in o lder populations tend to be fewer and larger but heterogeneous in scal e. It has also been possible to verify the persistence over several ye ars of mycorrhizal mycelial individuals. Such findings represent only the first step in the study of the spatiotemporal dynamics of ectomyco rrhizal fungi, which promises to be a rich and important field for fut ure research. Concepts concerning the process and mechanisms likely to affect distribution patterns are discussed.