What is a disturbance? Consider the role of fire in a forest. Compare the consequences of high-frequency versus low-frequency fire, and high severity versus low severity of fire.

Which of the following organisms is mismatched with its trophic level?a. algae—producerb. phytoplankton—primary consumerc. carnivorous fish larvae—secondary consumerd. eagle—tertiary or quaternary consumer

Food chains are sometimes short becausea. only a single species of herbivore feeds on each plant species.b. local extinction of a species causes extinction of the other species in its food chain.c. most of the energy in a trophic level is lost as energy passes to the next higher level.d. most producers are inedible.

Which of the following best illustrates ecological succession?a. A mouse eats seeds, and an owl eats the mouse.b. Decomposition in soil releases nitrogen that plants can use.c. Grasses grow in a deserted field, followed by shrubs and then trees.d. Imported pheasants increase in numbers, while local quail disappear.

Which of the following could qualify as a top-down control on a grassland community?a. limitation of plant biomass by rainfall amountb. influence of temperature on competition among plantsc. influence of soil nutrients on the abundance of grasses versus wildflowersd. effect of grazing intensity by bison on plant species diversity

The most plausible hypothesis to explain why species richness is higher in tropical than in temperate regions is thata. tropical communities are younger.b. tropical regions generally have more available water and higher levels of solar radiation.c. higher temperatures cause more rapid speciation.d. diversity increases as evapotranspiration decreases.

Draw a vertical food chain (part of a food web) showing that sea urchins eat kelp and that sea otters eat sea urchins. Use this model to (1) show or explain how a trophic cascade works; and (2)offer an explanation for why otters are considered a keystone species.

Community 1 contains 100 individuals distributed among four species: 5A, 5B, 85C, and 5D. Community 2 contains 100 individuals distributed among three species: 30A, 40B, and 30C. Calculate the Shannon diversity (H) for each community. Which community is more diverse?

In Southeast Asia, there's an old saying: 'There is only one tiger to a hill.' In terms of energy flow in ecosystems, explain why big predatory animals such as tigers and sharks are relatively rare.