Tropical monodominance: A preliminary test of the ectomycorrhizal hypothesis

This study reports results from the first explicit test of the ectomycorrhi zal hypothesis for tropical monodominance in the Ituri Forest of the Democr atic Republic of Congo (formerly Zaire), where the canopy tree Gilbertioden dron dewevrei forms large, monospecific stands. To test the hypothesis that ectomycorrhizae are important to the success of dominant species; we surve yed the mycorrhizal status of dominant species, as well as other common, bu t not dominant, species in the forest. The survey reveals that two dominant species, Gilbertiodendron dewevrei and Julbernardia seretii, form ectomyco rrhizae and vesicular-arbuscular mycorrhizae, while Cynometra alexandri, an other dominant, forms only vesicular-arbuscular mycorrhizae. These results, along with those of other species in this and other forests, are discussed within the context of the ectomycorrhizal hypothesis for tropical mondomin ance. This study demonstrates that the relationship between EM and tropical monodominance is more complex than has been previously recognized.