Species Richness varies by environment, not only due to the latitude that the environment is in but also the abiotic factors of the environment itself.
Terrestrial Environments
Elevation, temperature, and precipitation are all important abiotic factors in a terrestrial environment. As elevation increases, temperature decreases and precipitation increases.
Species richness increases in environments with warm temperatures and more precipitation. However, at higher elevations, weather conditions are harsher, so species richness decreases.
Deviations from species richness trends can occur, for example, in mountain ranges.
Aquatic Environments
Water depth, temperature, sunlight, and dissolved oxygen are important abiotic factors in an aquatic environment. As water depth increases, temperatures and sunlight decreases.
Species richness increases in environments with warmer temperatures and more sunlight, which is typically closer to the surface of the water.
Deviations from species richness trends can occur due to ocean currents.
In freshwater ecosystems, important abiotic factors include water velocity and pH levels.
In marine ecosystems, important abiotic factors include ocean currents, nutrients, and how close the ecosystem is to a land mass.