It is only in recent times that scientists have looked carefully at the elephants that live in the rainforest of Africa and found that actually they are a different species to the savanna elephant.
While there are areas of forest such as the Udzungwa mountains in Tanzania, which are surrounded by Savanna, that are inhabited by Savannah elephants, this is rare.
The African forest elephant is a distinct animal that is spread out throughout the Congo Basin. It is smaller with straighter tusks (as it lives in forest the wide spread tusks of Savannah elephants would get in the way) and smaller ears. The poaching of Savannah elephants increased after southern African countries were allowed a one off sale of their ivory stocks, and while some poaching of forest elephants was going on, this “one off sale” (southern African countries started talking about a repeat almost instantly) increased demand.
The generally recognised idea is that every few years, if lots of ivory is released in one go, the price falls so low that it is not worth the risk that congress with it. Elephants are highly intelligent animals very capable of doing serious injury to people who get to close, particularly if they feel threatened. Due to their ability to communicate over large distances once one is killed all others will be highly aggressive (an added problem as it reduces the money from photographic safari).
Unfortunately, on this occasion countries who had no history of ivory carving or ownership started reading legal ivory and wanted more than was provided. Furthermore China with its large and newly created wealthy middle class, proved a fertile market particularly as it came to be seen as a status symbol.
As such when the legal ivory supply ran out, the markets looked for other places to get it. The Selous in Tanzania lost 80,000 elephants in 4 years.
However, it quickly became apparent that forest elephants were harder to protect, and so came the massacre of the Congo basin elephants. Unfortunately, being straighter forest elephant tusks are easier to work with so enhancing the poaching.
There are small areas where elephant have largely escaped, such as Gabon, but in general there had been as rapid destruction of these animals, and in areas local extinction.
It should be noted that as ecosystem engineers forest elephants are highly important and forests without them are more at risk from many threats.