Ecological Succession

Primary and secondary succession: from bare rock to climax community

Ecological succession is the process by which the species structure of an ecological community changes over time. Primary succession occurs on newly exposed surfaces (lava flows, glacial retreat) with no prior soil. Lichens and mosses (pioneer species) break down rock, creating thin soil. Grasses and small herbs follow, then shrubs, and eventually trees form a climax community. Secondary succession occurs on disturbed land that retains soil (after fire, logging, farming). It proceeds faster because soil nutrients and seed banks remain. Key metrics change predictably: species richness increases, biomass accumulates, nutrient cycling intensifies, and food web complexity grows. Disturbance events (fire, storm, disease) can reset succession partially or fully, creating a mosaic of successional stages across a landscape.