A. Terminology

1. Ecology is the study of interactions (1) between organisms and (2) between organism and its surrounding.

1. Biotic environment consists of all the living things that an organism interacts with. It consists of food chains and food webs. The organisms are INTERDEPENDENT.

1. Abiotic environment consists of physical, non-living factors.

For example in a mangrove ecosystem, the abiotic factors that affect the species found in that area are:

oxygen content and salinity of the soil and water.

1. A habitat is the place where an organism lives. Some organisms have structural adaptations to suit their environment.

5. Population is a group of organisms of the same species that live together in a habitat. Eg All the Avicennia trees in Sungei Buloh Nature Reserve make up a population.

6. Community is all the population living and interacting with one another in a habitat. For example, the mangrove community at Sungei Buloh Nature Reserve is made up of mangrove trees and animals like horseshoe crabs, fiddler crabs, mudskippers and sandflies.

7. Ecosystem is a community of organisms interacting with one another and with its abiotic environment. For example the ecosystem of the mangrove swamp is made up of all the organisms in the mangrove community and the abiotic components.

• • Non-cyclic flow of energy

  • Cyclic flow of nutrients

The flow of energy and nutrients occurs through (1) producers, (2) consumers and (3) decomposers.

8. Ecological community consists of different populations of plants and animals living together and interacting within the same environment. The various groups of living organisms in gardens, forests, ponds, coast and oceans are examples of ecological communities.

Consider this food web at the mangrove swamp

The various populations of organisms at the mangrove swamp live interdependently. A change in one population affects the other populations of the community. If the mangrove crab population decreases, the population of mudskippers may also decrease because there is less food for the mudskippers. Mudskippers may also feed on more insects and worms, causing the population of insects and worms to decrease.