Test Taking Strategies: Ecology

Ecological succession leads to the sustainability of life in an ecosystem. Succession is the observed process of change in the species structure of an ecosystem. The community begins with relatively few pioneering plants and animals and develops through stages of increasing complexity until it becomes stable. Succession may be initiated either by formation of new, unoccupied habitat such as the formation of an island or by some form of disturbance such as fire in an existing ecosystem. Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession.

If a tornado destroys a deciduous forest, what kind of succession follows?

• classic ecosystem

• climax community

• primary succession

• secondary succession

On May 18, 1980, the vertical eruption plume from Mount St. Helens continued for 9 hours. Ash rose 15 miles into the air and eventually encircled the globe. The eruption profoundly changed the area, creating a mosaic of disturbance zones, ranging from areas where all life perished to zones with much survival. One location, the Pumice Plain, was left completely barren. Yet scientists discovered the prairie lupine, a purple-blue wildflower legume, growing on the Pumice Plain in 1982. The first seeds likely arrived by wind from surviving individuals high on the volcano’s slopes and the lupine patches became biological hotspots over the years. How did this one plant species contribute to the early stages of succession on the Pumice Plain? Choose ALL that could apply.

• Lupine served as a food source for moose and elk living in the area.

• Like other legumes, lupine improve the soil by fixing atmospheric nitrogen.

• Lupine nectar attracted bird species, and they in turn dropped seeds of other plants in the area.

• Surviving pocket gopher survived on lupine and insects, mixing new deposits with old and enriching the soil.

• The plants attract insects, many of which ultimately die on or around the plant, adding organic matter to the substrate.

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NGSS.MS-LS2-4

NGSS.MS-LS2-1

NGSS.MS-LS2-3

Ecological succession leads to the sustainability of life in an ecosystem. Succession is the observed process of change in the species structure of an ecosystem. The community begins with relatively few pioneering plants and animals and develops through stages of increasing complexity until it becomes stable. Succession may be initiated either by formation of new, unoccupied habitat such as the formation of an island or by some form of disturbance such as fire in an existing ecosystem. Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession.

What process is occurring in the illustration?

• classic ecosystem

• primary succession

• secondary succession

• climax community

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NGSS.MS-LS2-4

Examine the model for ecological succession of a pond over time. Each frame represents a snapshot of the biotic and abiotic conditions of the pond at a particular point in time. Which frame(s) represent(s) conditions suitable that would support submerged plants and invertebrates that can tolerate a sandy bottom? Choose ALL that appply.

• A

• B

• C

• D

• E

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NGSS.MS-LS2-1

Mount St. Helens erupted in 1980 and over 200 square miles of pristine forest were buried under millions of tons of lava, ash, mud, and avalanche debris. Just a year after the eruption, lupine plants are seen on the pumice plain. Lupine is a herbaceous perennial. It is:

A Nitrogen Fixer

Short-lived

Dynamic Accumulator

Beneficial Insect Attractor

Beneficial Insect Shelter

Ground Cover

Edible Seeds

As the mountain sleeps, wildlife bounces back: gophers are seen, surviving by eating the lupine.

The top of Mount St. Helens was considered to be alpine tundra. How can these two organisms, the lupine and the gopher, aid in succession on Mount St. Helens?

• The lupine is a pioneer species. It adds oxygen to the ecosystem. The gopher relies on the lupine for food and oxygen.

• Both the lupine and the gopher improve air quality; the gopher releases carbon dioxide and the lupine uses the oxygen for photosynthesis.

• The lupine and the gopher act as soil formers by decomposing the lava that is found on Mount St. Helens as a result of the volcanic eruption.

• Both the lupine and the gopher improve soil quality; the lupine fixes nitrogen and adds organic matter. The gopher adds organic matter and aerates the soil.

Tags

NGSS.MS-LS2-4

NGSS.MS-LS2-3