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| Question | Answer |
| Succession | temporal change in community composition -most studies are on plants |
| Primary Succession | begins on bare rock or sand (no soil) |
| Secondary Succession | begins on soil |
| Climax | final stage of primary & secondary succession |
| Observtional Study of Primary Succession | Glacial Moraines in Southeast Alaska: -Glacier is retreating and uncovering a forest from oldest to youngest -moss, cottonwoods, alder, spruce trees |
| Observational Study of Secondary Succession | Old Fields in North Carolina: -succession of plants on abandoned farms -crabgrass, horseweed, aster, pine trees, oak |
| General Patterns on Early and Late Successional Plants | -know table -E=r-selected -L=K-selected |
| Biomass and Productivity -2 graphs | . . |
| SuperOrganism Hypothesis- Classic Theory | -communities are fundamental units of highly integrated species -succession proceeds in a predetermined sequence toward the climax, analogous to development from an embryo into an adult |
| Individualist Hypothesis | -communities are collections of non-integrated species with similar physical requirements -succession does not proceed towards a predetermined climax |
| Facilitation | -E--+->L -only can initially colonize -L requires E first E facilitates L -Superorganism Hypothesis -common in stages of primary succession |
| Tolerance | E<---(-)---L -E is a better disperser -L is more tolerant to crowded conditions and outcompetes E -r-K Theory |
| Inhibition | E<---(-)--->L -E is a better disperser -E inhibits L -L live longer than E |
| Observational Study of Tolerance Model | Old Fields in North Carolina: -Broomsedge is tolerant to low soil moisture and excludes Aster -Pines are also tolerant to low soil moisture and when they grow tall they shade the Broomsedge -Oak trees are more shade tolerant and exclude Pines -Experiments showed that pine seeds can grow immediately after a field is abandoned -pine seeds can't germinate under shade, but oak seeds can |
| Observational Study of Facilitation Model | -Initially, substrate has high pH and low Nitrogen which can only be colonized by mosses and weeds -Mosses and weeds add some N and form some soil necessary for willows, cottonwood and alders -Alders have root nodules with N fixing bacteria and leaves are acidic – decreases pH and increase N of soil, conditions necessary for spruce and hemlock -Facilitaiton: early species modify the environment in a way that allows later species to colonize. |
| Experimental Study of Facilitation Model in Marine Systems | Hydroids & Bacteria: Number of Hydroid colonies per slide: -bacteria present =many -bacteria absent= few |
| Experimental Study of Tolerance Model of Marine Systems | Succession of Intertidal Organisms: -Barnacles settle first -Mussels settle in between barnacles, grow fast and exclude barnacles -When barnacles were experimentally removed, mussels settled -Tolerance: anyone can colonize |
| Experimental Study of Inhibition Model in Marine Systems | -Green – early successional, weak structural support, short life span -Red – late successional, strong structural support, long life span -Conducted a replicated controlled field experiment designed to test the 3 models of succession: KNOW CHART & RESULTS -Inhibition: red live longer because they have stronger holdfasts |
| Practical Applications of Model of Succession | -If Facilitation: encourage early species -If Inhibition: remove early -Role of herbivores may be important |
| Experimental Field Study of Inhibition Model on Herbivory | -Early inhibit colonization of late algal species -Snails prefer early-successional algal species -Colonization of Late Species: snails excluded =slow & snails present=fast -Snails removed the early species, allowing faster colonization of late species |
| Terrestrial Studies | -Cates: slugs preferred early successional annual weeds over perennials -Otte: grasshoppers preferred late successional shrubs over annuals -Slugs hasten succession whereas grasshopper impede succession -Morris: Outbreaks of Spruce budworm kill spruce trees, allowing early species to colonize |
| Relationship between Species Diversity and Successional Stage: -Classic vs Intermediate Disturbance hypothesis -Study of Algae graph -Study of Tropical Reef graph | .vs. . . |
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