Practice question

Secondary succession follows disturbance of a previously established community when soil and at least some biological legacies remain. Examples include recovery after fire, windthrow, logging, cultivation, or abandonment of pasture. Surviving roots, seed banks, spores, soil microbes, nutrients, and nearby source populations accelerate recolonization. Grasses and fast-growing shrubs may appear first, followed by trees and more shade-tolerant species, although pathways depend on disturbance severity, climate, and invasive species. Primary succession instead begins on surfaces lacking developed soil, such as new lava, recently exposed glacial deposits, or bare rock, and often features lichens among early colonists. Secondary succession can occur around aquatic margins, but “occurs in water” does not define it. Nor does it begin in a completely lifeless area. The retained soil is the major mechanistic distinction: it preserves fertility and propagules and shortens the time needed to rebuild biomass. Therefore, a disturbance within an established community accurately describes the setting in which secondary succession proceeds.