A microsite is a term used in ecology to describe a pocket within an environment with unique features, conditions or characteristics.
Classifying different microsites may depend on temperature, humidity, sunlight, nutrient availability, soil physical characteristics, vegetation cover, etc.
This is because plants and other autotrophs get nutrients (nitrogen, phosphorus, potassium, calcium, magnesium and Sulphur) they need from soil and water available in their microsite.
Animals are influence by the soil physical characteristics for example where a fish will survive is not the same like that of a camel or goat.
While some may have, some condition may arise to render those ingredients not available again in the environment such as pollution or invasive species.