The world is a very green place. Plants can be found almost everywhere on Earth – in fields, on mountains, in cracks in sidewalks, and under the oceans.
When you find one plant, you'll usually find another. Different plants living together in the same area form a "plant community."
The fact that the plants are neighbors means they affect each other in certain ways. Plants can compete for the same water and nutrients in the soil. One plant may block out another's sunlight. One type of plant may crowd out another type.
Pick a plant community: a clump of trees, a group of shrubs, a lawn, a grassy field, the edge of a stream, the steep slope of a hill, a vacant lot, or cracks in a sidewalk. Get ready to make notes and sketches (these don't seem important until you can't remember something later!).
What's the dominant plant in the community you're exploring? In every plant community, certain plants dominate. The dominant plants are the ones that determine what other kinds of plants grow around them (i.e. they affect the sunlight and water available). Dominant plants are usually the largest, most numerous types present. For example, ragweed might be the dominant plant in a field, while oak may be the dominant plant in a forest.
How many layers can you find in the plant community? Most plant communities have at least two layers of life. The highest layer is usually the one in which the dominant plant is present. What types of plants are present in each layer? For example, the upper layer in a field may be ragweed, and the lower layer may be grass of some sort.
Look for non-green plants (e.g. mushrooms) growing on decaying leaves and branches.
Take a plant census. How many different plants can you find in the plant community: more than 10? more than 50? How similar are they in height, color, and number? You may want to identify plants using a plant identification guide.
Explore and compare several plant communities. How are plant communities like human communities?