9 Biospheres to ecosystems
9.1 Overview
Introduction DUMMY
Inthis 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.Key concepts- 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 decom-
posers. - 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.
9.2 Biosphere
Thebiosphere refers to all living organisms on Earth and is often called the global ecosys-
tem. The biosphere interacts with other spheres, such as the lithosphere, atmosphere and
hydrosphere. Each of these spheres is discussed briefly below:256 9.1. Overview