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#ecological dominance

2 public questions tagged with this topic.

Competitive species dominate in:

“Low disturbance, high nutrients” for competitive species dominate in. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The remaining alternatives—“High stress and low nutrients”, “High disturbance, high stress”, “Arctic conditions”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Selection favors the schedule that increases lifetime reproductive success under local mortality and resource conditions. Body size, development time, fecundity, parental investment, and generation length consequently tend to covary. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.

Ref: Plant Strategies and Vegetation Processes, Grime, 2nd Ed.

What increases the chance of dominant species being present?

Greater species richness increases the sampling probability that a highly productive or otherwise dominant species is included in a community. This selection effect can raise measured ecosystem function even without every species contributing a unique mechanism, because diverse assemblages draw more species from the regional pool. Species richness counts taxa but does not show their abundance, traits, or interaction strengths. Dominant species may control bulk process rates, rare species may provide specialized functions or future insurance, and predators can restructure whole food webs through indirect effects. Functional groups summarize role overlap, while keystone effects identify unusually strong influence. Separating these dimensions explains why equal losses of richness can have very different ecological consequences and why conservation cannot rely solely on the number of species remaining. In this context, the keyed term, High richness, identifies the relevant mechanism or quantitative relationship and links the observed pattern to its underlying ecological cause.

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 20