1.4 Human Activities and the Natural Balance
Completion requirements
Unit A
Module 2 ~ Lesson 1
Human Activities and the Natural Balance
- Productivity is impacted by a variety of factors.
- Clear-cutting to make room for agriculture or commercial development decreases ecosystem productivity. Even though crops provide a means of capturing the Sun's energy, uniform crops do not provide the same ecosystem productivity as a diverse ecosystem.
A Diet to Change the World
Even our diet has an impact on the carbon footprint we leave on our Earth. Scientists have suggested that reducing the amount of red meat that we eat to about one hamburger a week could help reduce carbon emissions that are causing catastrophic effects on the global climate.
Algal Blooms
Human activities can disrupt the balance of biogeochemical cycles. Nitrates, nitrites, and phosphates are sources of nitrogen and phosphorus that are dissolved in water. Although these are naturally occurring, excess nutrients in lakes and oceans can cause algal blooms. Algae is an aquatic photosynthetic organism. When a body of water becomes crowded with algae, it blocks the sunlight, and the algae can not photosynthesize. Algae respire until there is no oxygen available and then die and decompose. It is the decomposing algae that cause the dead zones in lakes and oceans.
Algal blooms can be prevented by adding plants that use the nutrients or animals that consume the algae to restore the balance.
Algal blooms can be prevented by adding plants that use the nutrients or animals that consume the algae to restore the balance.
Christian Fischer [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons
Self-Check
Read
Answer:
Algal beds and reefs make up a very small percentage of the Earth's surface area, yet have the highest productivity.
Algal beds and reefs make up a very small percentage of the Earth's surface area, yet have the highest productivity.
Answer:
The number of producers present in a tropical seasonal forest would be greater, as would the amount of rainfall. There would also be more heat and light available for more of the year than in the arctic.
The number of producers present in a tropical seasonal forest would be greater, as would the amount of rainfall. There would also be more heat and light available for more of the year than in the arctic.
Answer:
People depend on net productivity for food from plants and animals. Additionally, they use plants for fuel, clothing, and construction.
People depend on net productivity for food from plants and animals. Additionally, they use plants for fuel, clothing, and construction.
Answer:
Humans reduce the net productivity of an area by clear cutting to build roads and houses and to develop agriculture and industry. Indirectly, pollutants from human activities can harm organisms, reducing population numbers and diversity.
Humans reduce the net productivity of an area by clear cutting to build roads and houses and to develop agriculture and industry. Indirectly, pollutants from human activities can harm organisms, reducing population numbers and diversity.
Read "Human Activities and the Natural Balance" and "Thought Lab 2.4: Evaluating Water Treatments" on pages 58 to 60 of your textbook.