A CRITIQUE OF THE ROLE OF ECTOMYCORRHIZAS IN FOREST ECOLOGY

This paper identifies areas of mycorrhizal ecology that the authors believe are crucial for advancing our understanding of the role of mycorrhizas in forest ecosystems. Increased research is needed into the relationships between plant carbon fixation and allocation and nutrient acquisition by mycorrhizas in many forest ecosystems and for different plant physiological stages. These comparisons need to consider not only how symbiotic associations modify plant uptake of nutrients but the interactions between mycorrhizas and decomposer microbes and fauna, and how these interactions influence the conservation of, or competition for, available nutrients. The authors identify four areas of future study that should be accorded priority: (1) the cost-benefit ratio (to the host) of maintaining mycorrhizal fungi on roots and the optimal mycorrhizal biomass that can be supported before the cost-benefit ratio becomes unfavorable; (2) the significance of mycorrhizas in storing nutrients in ecosystems; (3) the significance of interconnecting (naturally grafted) roots relative to the links between different roots attributable to mycorrhizal hyphae; (4) the ability of mycorrhizal fungi to use complex organic substrates as sources of nutrients (such as N and P) in forests.