Lafarge eco systems are a company in kenya who have, over thirty years, created complete ecosystems from depleted quarries. They rehabilitate the wasteland by planting casuarina pine (an australian tree) which is the only tree to thrive in the limestone conditions. Once grown, the pine nettles drop to the ground and decompose which add nutrients to the ground. This takes a long time, but they discovered the red millipede (locally abundant) was able to feed and digest the nettles which greatly sped up the process. Once the layer of nutrients is returned to the ground other insects, birds and animals return (birds, bats etc) which add to the dispersal of nutrients, and then they thin the pines and introduce local plants and vegetation.
They have created a variety of ecosystems including grasslands and have even restored wetlands from sterile, murky quarry water. This land is protected, and they have introduced mammals such as giraffes, buffalos, and hippopotamuses successfully. Incredible stuff. I became aware of them because of Owen and Mzee. You'd probably remember this story from the huge tsnumai. A baby hippo had been washed out of a river in Kenya and into the sea and he was stranded on coral. He was rescued by Lafarge and named Owen. When they released him in the park he immediately latched onto a 100 year old tortoise named Mzee who is now his adopted mother. It's seriously cute. Anyway their keeper has kept a blog from the very beginning and continues to update it every couple of days. Have a look here: http://www.lafargeecosystems.com/main/blog.php?mod=view&page=1