Analyze Ecosystem Change and Recovery Practice Test

After a major flood, a stream channel was scoured and much of the insect community was washed away. Scientists counted aquatic insect families (a measure of richness) at one site each month.

Aquatic insect family richness:

• Before flood: 19
• 1 month after: 5
• 3 months after: 11
• 6 months after: 16
• 12 months after: 18

Based on these data, about how long did it take for richness to return close to its pre-flood level?

An abandoned agricultural field is being monitored as it returns to a more natural plant community. Researchers recorded total plant species richness and the percent cover of native perennial plants.

Time since abandonment:

• 1 year: richness 18; native perennial cover 5%
• 5 years: richness 27; native perennial cover 22%
• 12 years: richness 33; native perennial cover 48%
• 25 years: richness 35; native perennial cover 61%

Which statement is best supported by these measurements?