With environmental issues high on every agenda, the term "ecology" trips easily off most tongues. Are we confident of its meaning as we use it?
A translation from the Greek "oikos" tells us that ecology is the study of the house or home. The home of a plant or animal has both living and non-living components.
The Community
A group of plants and animals living together in a place at one time is called a community. We can identify communities on both land and water, to include a forest community, a pond community, a desert community or a coral reef community. At micro-scales, a community on a single tree branch might include mosses and lichens, insects, birds and small mammals. The living things within the community interact with each other, possibly through a food chain or food web relationship, in which insects may eat leaves and birds eat the insects. Trees in a forest provide shelter and breeding sites for some of the animals in the community. In relationships with benefit to both parties, insects pollinate plants and fruit-eating birds and mammals disperse seeds.
The Ecosystem
The non-living components of the home of living things include the sun's energy, the earth and its minerals and nutrients, water and the atmosphere. The community together with its non-living surrounds is called an ecosystem. Once energy, earth, water and gases are considered in addition to living things, interactions between them become more complex. Today, an understanding of the exchange of gases between living things, fossil fuels, the sea and the atmosphere is critical to our approach to climate change. Decomposers, including fungi and bacteria, are an important link between living things and the soil and atmosphere, breaking down waste products and dead plants and animals.
So the study of living things and their homes can be incredibly complex, as each new understanding raises more questions about how parts of an ecosystem relate to each other, how they change with time, and how they are affected by the actions of humans (who are part of most ecosystems) or natural events. Sustainable living for humans and conservation of biodiversity are two major areas of ecological study. Like other topics, they can be investigated holistically, or can be broken down into sudies of component parts and processes.
To encapsulate these ideas, C.J. Krebs in 1972 developed a widely accepted definition (Ecology, Harper and Rowe, New York):
"Ecology is the scientific study of the interactions that determine the distribution and abundance of living organisms."
