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# Chapter 8: Biospheres to ecosystems

## 8.1 Overview (ESG9T)

### Introduction (ESG9V)

In this chapter learners are introduced to some of the interactions that occur in nature, and to the terminology that describes them. The interaction of organisms with each other, and with their environment, is known as the study of ecology. Learners will grasp the meaning of these terms and concepts by using them to describe the familiar contexts of both Southern Africa and their local area. This section builds on the knowledge that was taught in the Senior Phase, and links to Grade 11 across all the appropriate strands.

Learners will revisit the concept of the biosphere and the inter-connections that occur between the components of global ecosystems (the hydrosphere, lithosphere and atmosphere).

Learners will then be introduced to the terrestrial and aquatic biomes of Southern Africa. They should understand how climate, soil types and vegetation influence the organisms found in each biome. The learners also need to know the location of the different biomes in South Africa.

The concept of environment will be introduced and the effect of human activities on the environment will be discussed. The concept, structure and functioning of ecosystems needs to be discussed in detail with the learners. This will include a detailed descriptions of abiotic and biotic factors.

Energy flow through the ecosystems and the relationship to trophic structure is also covered. Here the learners are introduced to the different trophic levels. Skills in drawing flow diagrams can be included in this section. Learners will also learn how all the important nutrients are cycled through the environment.

Finally ecotourism and its impact on the economy will be discussed. The ethics of responsible ecotourism and opportunities that arise from it can be debated in a class discussion.

• The biosphere consists of an interconnected group of living organisms. It is connected with components of the global ecosystem: the hydrosphere, the lithosphere and the atmosphere.
• Biomes are natural habitats for flora and fauna that extend to both aquatic and terrestrial regions.
• The location of biomes across southern Africa and in South Africa itself is governed by climate soils and vegetation.
• The environment consists of interactions between humans with the natural environment.
• The ecosystem brings together the various interactions between living organisms
• Abiotic factors affect the nature of an ecosystem. Such factors include physiographic factors (altitude, aspect and slope), soil quality (pH, humus content, texture, water retention capacity and air content); light (day length and seasonal changes); temperature (effect of day/night, seasons), water (the water cycle, as well as the nature of wetlands), atmospheric gases, wind
• Biotic factors that affect the ecosystem include producers, consumers and decomposers
• Energy flows through the trophic levels of an ecosystem and trace the relationships that exist in an ecosystem.
• Oxygen, carbon, nitrogen and water also cycle through the ecosystem.
• Ecotourism presents both opportunities and challenges for the preservation of our ecosystems.

In this chapter we will study the way the biosphere interacts with the atmosphere, lithosphere and hydrosphere. This will be followed by a description of the major aquatic and terrestrial biomes in South Africa. We will then learn about the abiotic and biotic factors that make up an ecosystem and examine how these factors interact. This will be followed by a discussion on energy flow and the different trophic levels in an ecosystem that can be represented by either a chain, pyramid or web. We will next look at how all the important nutrients are cycled through the environment. We will conclude this chapter with a discussion of ecotourism in South Africa.

• The biosphere consists of all the living organisms on Earth.
• The biosphere interacts with the hydrosphere, the lithosphere and the atmosphere.
• Biomes are natural habitats for flora and fauna that extend to both aquatic and terrestrial regions.
• The location of biomes across southern Africa, and in South Africa itself, is governed by climate, soils and vegetation.
• The environment consists of living (biotic) and non-living (abiotic) components which interact.
• The ecosystem brings together the various interactions between living organisms.
• Abiotic factors affect the nature of an ecosystem. Such factors include physiographic factors, soil quality, light, temperature, water, atmospheric gases and wind.
• Biotic factors that affect the ecosystem include producers, consumers and decomposers.
• Energy flows through the trophic levels of an ecosystem tracing the relationships that exist in an ecosystem.
• Oxygen, carbon, nitrogen and water also cycle through the ecosystem.
• Ecotourism presents both opportunities and challenges for the preservation of our ecosystems.

atom $$\rightarrow$$molecule$$\rightarrow$$cell$$\rightarrow$$tissue$$\rightarrow$$organ$$\rightarrow$$system$$\rightarrow$$organism$$\rightarrow$$ecosystem