FACT
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SHORTCODEat
http://www.everythingscience.co.za9.5 Ecosystems
Anecosystem is complex system that consists of all the living organisms in a particular
area as well as the environment with which the organisms interact. The living organisms
and non-living components of the ecosystem interact in such a way as to maintain balance.
Ecosystems are divided intobiotic(living) andabiotic(non-living) components respectively.
Each component is discussed in detail below.
Biotic components DUMMY
Biotic components are living things that shape the ecosystem. Each biotic factor needs energy
to do work and for proper growth. To get this energy, organisms either need to produce their
own energy using abiotic factors, or interact with other organisms by consuming them. Biotic
components typically include:
- Producers: also known as autotrophs include all green plants. producers make their
own food using chemicals and energy sources from their environment. The producers
include land and aquatic plants, algae and microscopic phytoplankton in the ocean.
Plantsuse photosynthesis to manufacture sugar (glucose) from carbon dioxide and
water. Using this sugar and other nutrients (e.g. nitrogen, phosphorus) assimilated
(taken up) by their roots, plants produce a variety of organic materials. These materials
include starches,lipids, proteins and nucleic acids. - Consumers: are also known as heterotrophs. They eat other organisms, living or dead,
and cannot produce their own food. Consumers are classed into different groups de-
pending on the source of their food. Herbivores(e.g. buck) feed on plants and are
known asprimary consumers. Carnivores(e.g. lions, hawks, killer whales) feed on
other consumers and can be classified assecondaryconsumers. They feed on primary
consumers. Tertiary consumersfeed on other carnivores. Some organisms known as
omnivores(e.g.crocodiles, rats and humans) feed on both plants and animals. Organ-
isms that feed on dead animals are calledscavengers(e.g., vultures, ants and flies).
Detritivores(detritus feeders, e.g. earthworms, termites, crabs) feed on organic wastes
or fragments of dead organisms. - Decomposers: (e.g. bacteria, fungi) also feed on organic waste and dead organisms,
but they can digest the materials outside their bodies. The decomposers play a crucial
role in recycling nutrients, as they reduce complex organic matter into inorganic nu-
trients that can be used by producers. If an organic substance can be broken down by
decomposers, it is calledbiodegradable.
Abiotic components DUMMY
Abiotic components are the non-living chemical and physical factors in the environment that
affect ecosystems. Abiotic components play a crucial role in all of biology. Abiotic factors are
broadly grouped intophysiographic,edaphicandclimacticfactors andatmospheric gases.
- Physiographic factors
Physiographic factors are those associated with the physical nature of the area. The main
physiographic factors we will look at are slopes, aspect and altitude.
Chapter 9. Biospheres to ecosystems 269