Maintaining Biodiversity: Grade 7 Science Lesson Notes

Lesson Overview and Academic Context

• Academic Year: 2024-2025

• Grade Level: Grade (7)

• Timeline: Week 4, Term 3

• Topic: Lesson 2: Maintaining Biodiversity

• Standard (MS-ETS1-1): Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.

• Primary Questions:

  • In what ways is biodiversity threatened?

  • How can we protect biodiversity and ecosystem services?

Core Methods for Protecting Biodiversity

• Habitat Restoration: This involves restoring damaged habitats and ecosystems to their original state. This allows organisms to live and grow in these areas once again.

• Conservation: The active process of keeping ecosystems healthy to prevent further degradation.

• Reforestation: The specific act of planting trees to replace those that have been cut down or burned.

  • Reforestation is critical because trees provide essential services: shelter, food, and clean air.

• Reclamation: This refers to the process of restoring land that has been disturbed or damaged by mining activities.

  • Similarity between reforestation and reclamation: Both techniques are used to restore land that was damaged by human activities.

Ecosystem Restoration Strategies

Restoration strategies help reverse the effects of environmental stressors (such as drought) and support the recovery of biodiversity. Restoration is necessary because it helps damaged ecosystems heal, brings back native plants and animals, improves soil and water quality, and supports overall ecosystem health.

1. Habitat Restoration: Returning damaged environments to their natural/original state.

2. Reforestation: Planting new trees to replace lost forest cover.

3. Reduce Pollution: Minimizing the use of harmful chemicals and ensuring the proper disposal of waste to keep soil, water, and air clean and safe for all living organisms.

4. Control Invasive Species: Removing non-native species to ensure that native species have adequate space, food, light, and nutrients to survive.

5. Mechanical Controls: Utilizing physical methods such as fences, barriers, manual weeding, or trapping to prevent the spread of invasive species.

6. Chemical Controls: The application of herbicides or pesticides to reduce or eliminate populations of harmful invasive species.

7. Biological Controls: The introduction of a specific species (a natural enemy) to naturally control or limit the population of an invasive species.

8. Sustain Populations: Implementation of laws and regulations to prevent overhunting and overfishing, allowing populations to recover to healthy levels.

9. Reduce Climate Change Impacts: Shifting toward renewable energy, recycling, and utilizing sustainable transportation (walking, biking, or public transportation) to reduce the emission of greenhouse gases.

Controlling Invasive Species: Detailed Methods and Examples

Invasive species cause significant harm to the environment, the economy, and human health. Various methods are employed to manage them:

• Mechanical Controls:

  • Definition: The use of physical barriers or manual labor.

  • Example: Installing a fence to block the spread of Japanese knotweed.

• Chemical Controls:

  • Definition: Applying chemical agents like herbicides or pesticides.

  • Example: Using an herbicide to kill invasive weeds such as purple loosestrife.

• Biological Controls:

  • Definition: Introducing a natural enemy (predator or parasite) to regulate the invasive population.

  • Example: Introducing weevils to control water hyacinth in waterways.

Impact of Human Activity on Biodiversity

• Forest Destruction: When forests are destroyed, the ecosystem is damaged, and biodiversity decreases.

• Overexploitation: This threat occurs when humans remove too many individuals from a population, such as overfishing in the ocean.

• Sustainability and Biodiversity: Biodiversity must be protected because it directly affects the resources humans use sustainably. Biodiversity maintains ecosystem health by:

  • Recycling and storing nutrients.

  • Maintaining water quality.

  • Stabilizing the climate.

• Environmental Policy: The Clean Water Act has positively affected biodiversity by regulating and reducing water pollution, thereby helping maintain biodiversity in aquatic ecosystems.

• Energy Choice: Solar power plants are better for biodiversity than coal power plants because solar energy does not cause pollution.

Ecosystem Data and Disturbance Recovery

The ability of an ecosystem to recover from a disturbance (resiliency) is often linked to its species variety. Below is a comparison of four ecosystems:

• Ecosystem 1:

  • Plants: $500$ individuals, $5$ species.

  • Animals: $300$ individuals, $4$ species.

• Ecosystem 2:

  • Plants: $300$ individuals, $10$ species.

  • Animals: $100$ individuals, $7$ species.

• Ecosystem 3:

  • Plants: $100$ individuals, $2$ species.

  • Animals: $200$ individuals, $5$ species.

• Ecosystem 4:

  • Plants: $50$ individuals, $6$ species.

  • Animals: $30$ individuals, $4$ species.

• Finding: Ecosystem 2 is most likely to recover from a disturbance because it possesses a greater variety (diversity) of species across both plant and animal categories compared to the others.

Questions & Discussion

• Question: Which of these support the statement that we must protect diversity because it affects the amount of resources we can use sustainably?

  • Response: Diversity maintains ecosystem health by recycling and storing nutrients, maintaining water quality, and stabilizing climate.

• Question: How is biodiversity affected when forests are destroyed?

  • Response: The ecosystem is damaged, and biodiversity decreases.

• Question: When humans remove too many fish from the ocean, which threat to biodiversity does this cause?

  • Response: Overexploitation.

• Question: Look at the pictures of the two power plants. One uses coal and the other uses sunlight (solar). Which one do you think protects biodiversity better?

  • Response: The solar power plant is better for biodiversity because it does not cause pollution.

• Question: What happens when we throw trash into the water?

  • Response: It makes the water dirty. Humans, plants, and animals all require clean water. Additionally, throwing trash in locations like streams takes away from the beauty of nature and interferes with recreational fun.

• Question: How are reforestation and reclamation similar?

  • Response: Both restore land that was damaged by human activities.

• Question: What are some methods that can be used to control invasive species?

  • Response: Mechanical controls, chemical controls, and biological controls.

• Question: How has the Clean Water Act affected biodiversity? Explain.

  • Response: It has helped maintain biodiversity in aquatic ecosystems by regulating and reducing water pollution.

Restoration strategies reverse environmental stress impacts and support biodiversity recovery. Key strategies include:

1. Habitat Restoration: Returning damaged environments to their natural state.

2. Reforestation: Planting trees to replace lost forest cover.

3. Reduce Pollution: Minimizing harmful chemicals and waste disposal to keep ecosystems clean.

4. Control Invasive Species: Removing non-native species to aid native survival.

5. Mechanical Controls: Using physical methods like barriers and manual weeding to prevent invasive spread.

6. Chemical Controls: Employing herbicides to reduce invasive populations.

7. Biological Controls: Introducing natural predators to manage invasive species.

8. Sustain Populations: Implementing regulations to prevent overhunting and overfishing.

9. Reduce Climate Change Impacts: Shifting to renewable energy and sustainable transportation to lower greenhouse gas emissions.