Catkins are most obvious in willows and their relatives and are recognized as drooping and caterpillar-shaped. For example, an oak-hickory forest might be dominated by both oak and hickory. Typically, communities are specific collections of organisms that interact with one another and the environment and are recognized in other locations in the world. The crown consists of the spreading upper branches and associated leaves of a tree. The term cultural describes human activities that are learned behaviors, such as language, customs, and education.
Diatoms are tiny one-celled algae that live in marine or fresh water.
Disturbance is a general term for a disruption of the natural environment. Disturbances in ecosystems can be the result of from human activity or natural phenomena. Diversity refers to the number of species types in a community. A richly diverse community would have many different types of organisms. Ecology is the study of the interrelationships among organisms and the relationships and interactions of organisms with their environment.