These must be shade-tolerant since they're growing under the canopy trees. The shrub layer varies depending on the kind of and location of the forest. The types of plants in the herb layer vary depending on the soil humidity and the deepness of shade in an ecosystem. The forest floor is mainly a site of decomposition. Fallen leaves and dead plants and animals are returned to the soil.
Stratification also occurs in large bodies of water such as lakes and oceans.
In these, the layers are distinguished by light penetration, temperature, amount of dissolved oxygen, etc. Light penetrates throughout the epilimnion, so photosynthesis occurs. The compensation level is the depth where light is so low that not much photosynthesis occurs. At this level, cellular respiration and photosynthesis balance each other, while above this level, there is more photosynthesis, and below this level, there is more respiration and decomposition. The profundal zone is the area beyond the depth of light penetration.