This principle directly challenges the assumptions of agribusiness and its reliance on monoculture, but it goes further than simply restoring the original diversity. As threats to existing biodiversity tend to vary by ecoregion, it is difficult to characterize any one strategy for reversing this and increasing diversity.
One could argue, also, that each virus, prion, bioinvader, exotic pet or other foreign species increases biodiversity - in the short term at least. In the longer run, they are likely to drastically decrease the diversity of any given ecosystem. Good examples include the devastation on Australian wildlife by human-introduced predators, and the loss of many wild plant species by terraforming and plowing huge regions of the Earth such as the Great Plains of North America. The time horizon to which one measures the increase matters.
Paul Hawken is a notable advocate of this strategy, which is thought to have benefits in topsoil renewal, natural water purification and sewage treatment, resistance to pests and increasing the yield of wild foods in any given region where this strategy is applied. Many anthropologists believe that in South America up to the 15th century, a deliberate strategy similar to these modern views was practiced in the Amazon River basin, by peoples who were almost wholly wiped out by disease brought by Europeans in the 16th century, which spread rapidly through the continent with little direct contact. They seem to have transplanted desired food plants and fed them with human waste (thus another principle "waste as food"). This increased local diversity and diet and also left large patches of exceptionally rich soil for which there is no plausible natural explanation.
Most gardening applies this principle on a small scale, usually placing complementary species in close contact as a strategy to reduce attraction of pests likely to devastate a monoculture, let root structure develop with less competition, and increase the aesthetic appeal of the garden.
An extreme view is that one best increases biodiversity by outright human speciation, the specialization of human beings for environments in which they live, and the genetic increase in their capacity to exploit natural food sources without outstripping them.
Another extreme view is that terraforming barren planets in space, and gradually developing new living planets with their own native ecologies, is a moral duty. The idea that this is how Earth's life actually originated is called Seeded Earth.
See also: Johnny Appleseed, space colonization, creationism