The influences of different species on ecosystems include supported species populations, species dominance, species competition and species interaction. This is a fluctuating system, with environmental changes affecting all of these aspects. Subtle changes in the ecosystem, such as a moderate increase in rainfall or abundance of food during a season, affects areas of the ecosystem and the ecosystem works to incorporate these changes and continue.
When species interaction makes a drastic change to the ecosystem, it can irreparably damage the ecosystem. These drastic changes in biodiversity may include the introduction of a new species, mass invasion of an outside species, species extinction and human activities. In some cases, you can repair or reverse these changes; however, the cost and technology required to do so is expensive. In the most severe cases, the damage caused by these drastic changes may not be reversible.
Changes in an ecosystem affect the biodiversity in different ways, depending on the specific differences of each system. This means that there is no way to accurately predict what affects a drastic ecosystem change will have on the biodiversity in the system. You have to evaluate each ecosystem separately for the specific changes after a large shift in biodiversity.
Initial changes in the biodiversity of an ecosystem may be minimal because in many ecosystems multiple species can carry out similar functions. The relative changes in the biodiversity of a system are protected until the severity of changes reaches a level where the ecosystem can no longer support the damage. The rate of damage to an ecosystem at that point increases severely.
High biodiversity creates species redundancy, ensuring that necessary functions within an ecosystem are maintained and supported. For instance, if a species primarily feeds from a plant that becomes extinct or its population decreases, the species can seek out another plant to eat. In this way, high biodiversity is the foundation of ecosystem stability, ensuring that a region is capable of sustaining its life.