A fallen oak log is covered with bracket fungi and beetle larvae that are breaking the dead wood down and releasing its nutrients into the soil. Which term names the role these organisms fill?

Rangers counted deer on an island every year. The herd grew quickly for twelve years, then stayed near 120 animals for the next twenty years. Which term names that steady 120?

In one spruce tree, one warbler species feeds on insects at the very top while another feeds on insects along the lower trunk. Which term names each bird's own role and way of living there?

Zebra mussels arrived in a lake in ship ballast water, spread over the rocks with no local predator eating them, and crowded native clams off the lake bottom. Which term names the mussels here?

The diagram traces energy through a meadow, from grass to a grasshopper to a shrew to a hawk. Which term names each single feeding step along that sequence?

A marsh survey lists every population living there, including cattails, frogs, herons, mosquitoes and bacteria, but records nothing about the water, mud or sunlight. Which term names what the list describes?

In a clear mountain lake, floating algae use sunlight and dissolved carbon dioxide to build their own sugars, and tiny shrimp feed on the algae. Which term names the algae's role in this lake?

A diving survey finds 210 fish species living on a healthy reef and only 30 fish species on a bleached reef a kilometer away. Which term names the measure that differs between the two reefs?

A lake report reads: 'Sunlight and nitrogen stayed plentiful all summer, but algae grew only where phosphorus was added, so phosphorus is the ____ for algal growth here.' Which term completes the report?

A volcano report reads: 'Two years after the lava cooled, crusty lichens and mosses were the first living things growing on the bare new rock; they are its ____.' Which term completes the report?

A survey report reads: 'We counted 340 gray squirrels across the whole twenty-hectare woodlot, all of them the same species; this is the gray squirrel ____ of the woodlot.' Which term completes the report?

A forest report reads: 'Two years after a storm flattened part of the woods, the same species had returned in about the same numbers as before, showing the community's ____.' Which term completes the report?

A stream report reads: 'At each site we measured water temperature, pH, current speed and dissolved oxygen. These ____ factors were recorded before any organisms were counted.' Which term completes the report?

A meadow report reads: 'Of all that the grasses captured from sunlight, roughly a tenth reached the mice, and a tenth of that reached the owls. We drew these shrinking amounts as stacked bars in our ____.' Which term completes it?

A poster shows one line, algae to snail to sunfish to heron, beside a tangle in which the sunfish, the heron and four other animals all share several prey. Which statement labels the two correctly?

A caterpillar chews holes in a living maple leaf while, on the ground below, mushrooms spread through a dead maple branch. Which statement labels the two organisms correctly?

In one pond, biologists count 480 bluegill sunfish. They also list every kind of fish, plant, insect and bacterium living in that same pond. Which statement labels the two counts correctly?

On a rocky shore, barnacles crowd one another for space, and the salt content of the splashing seawater also affects how many of them survive. Which statement labels these two influences correctly?

In a farm pond, the fish population stops growing near 500 fish because oxygen runs low in the warm summer water. Which statement labels these two correctly?

A cooled lava field has no soil at all, while an abandoned farm field nearby still has deep soil and buried seeds. Plants are moving into both. Which statement labels the two correctly?