Monodominance

Monodominance is an ecological condition in which a single species accounts for a large proportion of individuals, biomass, or canopy cover within a plant community, resulting in a visibly distinct vegetation type and typically reduced local species richness. The phenomenon is described most often in tropical forests, where a single tree species can form extensive monodominant stands, but it can occur in other ecosystems as well.

A monodominant stand is generally identified when the dominant species contributes a substantial share of stems, basal area, or aboveground biomass, leaving little room for other species in the immediate vicinity. Such stands may persist for long periods, especially if feedbacks reinforce the dominance. Mechanisms proposed to explain monodominance include: competitive advantages such as rapid early growth or superior shade tolerance; mutualistic relationships (for example, specific ectomycorrhizal associations) that enhance nutrient uptake; soil feedbacks through litter chemistry and nutrient cycling that favor the dominant; suppression of competitors via shading or allelopathy; and historical disturbance regimes that create enduring favorable conditions for the dominant species.

Consequences of monodominance include altered light environments, slowed species turnover, and changes in nutrient dynamics, all of which can influence ecosystem processes and resilience to disturbance. It is a topic of ongoing research and debate, with emphasis on disentangling the relative contributions of biotic interactions, soil properties, and historical context.

A classic example is the tree Gilbertiodendron dewevrei, which forms large monodominant stands in parts of West and Central Africa's tropical rainforests. Other regions report monodominant occurrences among different taxa.