Unit 2: Chapter 9

A community is all the living organisms in a habitat.

Plant communities that have many layers of vegetation can support more species of birds than a plant community that has a simpler structure.

The system formed by a community of living organisms interacting with one another and their physical surroundings is an ecosystem.

Community + physical surroundings = ecosystem

An ecosystem can be a small or large unit of study.

Ecosystems are systems that are largely self-sustaining.

• A habitat is a place where an organism lives.

• The environment of an organism includes both the non-living (abiotic) and living (biotic) surroundings of an organism.

• The environment provides an organism with it’s essential requirements.

The niche of a species is that part of the environment in which the species survives, reproduces and is likely to persist.

The physical environmental factors that affect the survival of organisms in fresh water include light, temperature, dissolved gases and nutrients.

• Soils are made up of different sizes, including gravel, sand, silt and clay, together with mineral nutrients and humus.

• Humus in soil holds particles together to form crumbs, which create pore spaces and help aeration.

Biomes are broad categories of ecological communities in the world, based on climate.

For example, in Australia we have the ‘desert and arid shrub lands’ and the ‘tropical rainforest’ biomes.

One of the best ways to study and ecosystem is to focus on a sample area. Samples can be located by using quadrats, transects and other techniques.