Legacy Effects: The Persistent Impact of Ecological Interactions

The term “legacy effect” has been used in ecology since the early 1990s by authors studying plant succession, invasive-plant impacts, herbivory impacts, ecosystem engineering, and human land-use impacts. Although there is some variability in usage, the term is normally used to describe impacts of a species on abiotic or biotic features of ecosystems that persist for a long time after the species has been extirpated or ceased activity and which have an effect on other species. For example, human agricultural activities may have a legacy effect on soil structure and vegetative communities that lasts for centuries and which alters current communities. The concept may be related to the idea of ecological inheritance in evolutionary biology but would refer only to a subset of the features of this concept. In particular, legacy effects could refer to those kinds of ecological inheritance where a physical or biological change in ecosystem state is caused by one species, where this change persists after the extirpation of the causal species and alters selection pressure of another species much later in time.