ABSTRACT
The competition among plants for nutrients is often given as a reason for the evolution of specific plant assemblages, by which some plant species are more able to access limiting nutrients than others. This is one of the prime reasons why plant succession occurs. The role of different mycorrhizal associates in the process of competition among plants for available soil phosphorus was investigated by Pedersen et al. (1999). They grew slash pine (Pinus elliottii) intentionally inoculated with the ectomycorrhizal fungus Pisolithus arhizus or fortuitously colonized by Thelephora terrestris and a native grass (Panicum chamaelonche), which associates with arbuscular mycorrhizae. Pine inoculated with P. arhizus took up more P when competing with the nonmycorrhizal grass than when competing with another pine, irrespective of the mycorrhizal status of the competing pine seedling. From an analysis of the phosphate uptake kinetics, it was found that pine is more competitive at higher nutrient concentrations, while the grass is more competitive at lower nutrient concentrations, suggesting a separation in niche between the two plants.
