Local extinction, or extirpation, is when a species or other taxon becomes extinct in a certain area. This is different from being extinct across the world (global extinction) because these species still exist outside of that area. Sometimes when this happens, it can have a very large effect on how the ecosystem works. This might be because that species was important in the food web. The species disappearing might cause more species to go locally extinct or the balance of biomass to change.