Practice question

Allogenic succession is driven mainly by forces external to the resident community, including erosion, sediment deposition, flooding, climatic shifts, or changes in hydrology. Such abiotic processes alter habitat conditions independently of biological modification and can redirect community composition. A disturbance changes the availability of space, resources, and biological legacies, creating opportunities for colonization. Whether succession is primary or secondary depends chiefly on the starting substrate and survival of soil, not simply on the identity of the disturbance. Colonists must arrive, establish, reproduce, and interact with residents; meanwhile they alter nutrient cycling, shade, moisture, and physical structure. These feedbacks create directional replacement, although repeated disturbance or environmental change may interrupt, reverse, or redirect the sequence. In this context, the keyed term, Abiotic factors like erosion, identifies the relevant mechanism or quantitative relationship and links the observed pattern to its underlying ecological cause. The distinction is testable by measuring changes in organisms, resources, or process rates through time rather than relying on the label alone.