In this Grade 5 lesson from Science: A Closer Look, Chapter 3, students explore how ecosystems change over time through both natural events and human actions, examining concepts such as succession, pioneer species, climax communities, and the differences between primary and secondary succession. Students also learn to distinguish between extinct, endangered, and threatened species, and investigate how organisms like beavers, elephants, and humans can cause changes that are beneficial, neutral, or detrimental to their ecosystems. A hands-on tree-ring analysis activity teaches students to interpret annual ring data as evidence of past ecosystem conditions such as drought, fire, and insect infestation.
Section 1
Ecosystems Change Through Natural and Human Forces
Ecosystems undergo constant changes from natural disasters, organism activities, and human actions. These changes can destroy habitats, alter environments, and affect organisms' survival in both harmful and beneficial ways.
Section 2
Species Face Extinction When Environments Shift
When organisms cannot adapt to ecosystem changes, they become threatened, then endangered, and potentially extinct. Habitat loss, pollution, hunting, and competition from introduced species threaten many organisms' survival.
Section 3
Pioneer Species Transform Barren Landscapes
Primary succession begins when hardy organisms like lichens colonize lifeless areas, breaking down rock and forming soil. This gradual process allows larger plants to establish, eventually creating complex ecosystems with diverse species.
Section 4
Ecosystems Rebuild Through Succession Stages
After disturbances like fires or abandoned farmland, secondary succession rebuilds ecosystems faster than primary succession. Early plant communities gradually shift toward a stable climax community of mature trees and associated organisms.
Section 5
Scientists Analyze Evidence to Track Environmental Impact
By collecting and interpreting data, scientists can identify relationships between environmental changes and organism health. The bald eagle's recovery demonstrates how analyzing evidence helps protect threatened species.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter
Expand to review the lesson summary and core properties.
Section 1
Ecosystems Change Through Natural and Human Forces
Ecosystems undergo constant changes from natural disasters, organism activities, and human actions. These changes can destroy habitats, alter environments, and affect organisms' survival in both harmful and beneficial ways.
Section 2
Species Face Extinction When Environments Shift
When organisms cannot adapt to ecosystem changes, they become threatened, then endangered, and potentially extinct. Habitat loss, pollution, hunting, and competition from introduced species threaten many organisms' survival.
Section 3
Pioneer Species Transform Barren Landscapes
Primary succession begins when hardy organisms like lichens colonize lifeless areas, breaking down rock and forming soil. This gradual process allows larger plants to establish, eventually creating complex ecosystems with diverse species.
Section 4
Ecosystems Rebuild Through Succession Stages
After disturbances like fires or abandoned farmland, secondary succession rebuilds ecosystems faster than primary succession. Early plant communities gradually shift toward a stable climax community of mature trees and associated organisms.
Section 5
Scientists Analyze Evidence to Track Environmental Impact
By collecting and interpreting data, scientists can identify relationships between environmental changes and organism health. The bald eagle's recovery demonstrates how analyzing evidence helps protect threatened species.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter