Practice question

At low disturbance frequency, long intervals allow biomass to accumulate and competitive hierarchies to develop. Species that are highly efficient at capturing light, nutrients, space, or another limiting resource can suppress and eventually eliminate weaker competitors. This competitive exclusion reduces local diversity, especially when no spatial refuges or temporal fluctuations interrupt dominance. Intermediate disturbance may periodically remove dominant biomass, open recruitment sites, and permit colonizers and slower competitors to coexist. At the high-disturbance extreme, only tolerant or rapidly reproducing species survive. This balance forms the classic mechanism behind the intermediate disturbance hypothesis. Colonization generally raises diversity when propagules establish rather than explaining low diversity. Predator suppression can sometimes allow a superior competitor to dominate, but it is a contingent trophic pathway, not the general low-disturbance mechanism. Nutrient depletion can influence competition, yet low disturbance does not necessarily imply depleted nutrients. Competitive exclusion is thus the direct theoretical explanation. The prediction is not universal: spatial heterogeneity, equalizing mechanisms, immigration, fluctuating resources, and natural enemies can maintain coexistence even without frequent physical disturbance.