Apart fro areas of the Congo and Amazon rainforests, and areas of Siberia canada and the Sahara, virtually all other ecosystems have been adversely affected.
Many ecosystems look intact, until we realize that important members from these ecosystems are missing. It is unfortunately true that humans are almost always responsible for these holes in the food web.
Many well known biologically diverse areas that at first glance look perfect are not. Areas such as the Kruger in South Africa: when I was there there was a list of 500 invasive plants, as well as various missing species. Thankfully, the Kruger still functions properly but there are many others that are less lucky.
What is particularly fascinating, is that the researchers found that many of these ecosystems could rapidly recover if specific missing species returned.
The most obvious species they found were elephants and wolves.
Ecosystems missing these animals are at particular peril.
In the west, the wolf was driven to extinction across much of its range. As an apex predator, they kept the herbivores moving and as a result, without them much needed vegetation is lost. Elephants are different.
In areas such as west Africa, rainforests are struggling: elephants were key seed dispersal mechanisms. This is because there are pests that specialize on almost all types of tree. This means that if you get more than 1 or 2 of the same species in one place, the pests will kill them. Elephants can carry the seeds dozens of miles and deposit them in their own pile of dung. For many species, the absence of forest elephants is likely to lead to the tree becoming rare or even disappearing from large parts of the forest.
The advantage of this research, is that with targeted reintroductions many ecosystems could be returned to health.
Another advantage of this approach, is that as these wild animals are often tourist draws it is possible that this move could be funded through tourism avoiding using already stretched government funds.
