Zonation refers to the patterns that are observed in a community over a distance, based on the distinct fauna and flora found along the area. Although the different zones are characterized by the dominant species inhabiting them, the separation of zones isn’t always a clear straight line, but instead there is some overlapping of species, particularly where the zones meet. Sometimes, however, the overlapping can disappear or be very small if one species completely out-competes the others by predation or competition over resources, and we can see clear-cut zonation.
The presence or abundance of a species in an area depends on different biotic factors, such as altitude, temperature, and salinity, as well abiotic factors, like predation and competition for food and space. This results in zonation, since every species is adapted to surviving specific environmental conditions that are not found everywhere. For instance, as we go up a mountain and the altitude changes, the species of plants and animals we find also change, depending on the altitude that they can tolerate to exist at.
Example of Zonation
Rocky shores often show very clear distribution of species in horizontal belts in the intertidal zone. Environmental factors, such as temperature, wind exposure, light intensity, wave action, and salinity, vary as we move up and down this area. Therefore, the intertidal communities create bands that differ in the species that occupy them.
Within it, the intertidal zone has been categorized into three parts: the high, middle, and low zones. These three zones differ in the amount of exposure to different environmental factors that they receive, so we find that each zone is occupied by different species of organisms depending on the different adaptations they posses. The mid intertidal zone is turbulent since it is being repeatedly submerged and exposed. On the other hand, the high zone is mostly exposed and the low zone is mostly submerged. This means that at the lower end, we can mostly find marine life, like seaweed and sea cucumber, while at the high intertidal zone we can find species that are adapted to being out of the water for most of the day, like some isopods and crabs. Keep in mind that some species may be adapted to survive in all intertidal zones, but may not be able to in some places or during certain times due to competition with other organisms for resources. This is unlike the way other species are restricted to a particular zone due to their inability to survive environmental conditions at other zones.