Natural regeneration is when plants or animals recover at a site without being reintroduced by humans. It is not magic. It arises from the resilience mechanisms developed by organisms (through natural selection over evolutionary time frames) in the presence of natural disturbances and fluxes in resources. (Think: natural droughts, fires, floods etc.)
Restoration intervention approaches diagram published in the (Australian) document: National Standards for the Practice of Ecological Restoration in Australia. Edition 2.2. Society for Ecological Restoration Australasia. Available from URL: http://www.seraustralasia.com/standards/home.html
Organisms in all ecosystems have evolved such resilience mechanisms for natural recovery. Some plants, for example, may have evolved a capacity for storing seed in the soil for long periods, waiting for the next competition-free window. Others may be capable of recovering from buried rootstocks or through colonization of seed from a nearby seed source.
Techniques to harness natural regeneration are many and varied and differ according to ecosystem type – as is shown by our many example projects accessible here – as well as degree of degradation.
Natural regeneration can be the sole or main source of species recovering on a site – or it can range from being a less major to a minor but important source – depending on the site’s remaining regeneration potential. It is important to try natural regeneration first before assuming reintroduction of seeds or seedlings is needed as natural regeneration can help us attain a more authentic matching of species to the site.