UNI101Y1 Study Guide - Introduced Species, Prunus Serotina, Digitaria
16 Feb 2013
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Bio120h lisa zhao 2011 | page 4. Tolerance and inhibition combine to influence the early stages of plant succession in old agricultural. First 3-4 years: species of crabgrass, horseweed, ragweed, aster, broomsedge replaced each other in rapid sequence (stress tolerant) Their indiv. life cycle determines its place in the successional seq. Crabgrass (rapidly growing annual) prominent during year when field is abandoned. Horseweed (winter annual; seeds germinate in autumn) disperses well, develops rapidly, dominates 1yro fields, seedlings require full sunlight; quickly replaced by shade- tolerant species. Early succession is dominated by tolerance (colonizing species disperse and cope w/ harsh conditions) inhibition then comes into play. Decaying horseweed roots stunt seedling growth (self- limiting) growth inhibitor; it is a by-product of adaptations that increase fitness during year 1 of succession. Ragweed (summer annual) dominates fields that are plowed under late autumn (instead of horseweed) Invasive species often dominate during early succession.
