Nemesis
Teak is found in the tropical, moist regions with heavy rainfall, and are thickly forested. Felling of teak trees in this region results in a replacement by Xylia xylocarpa. And teak never reinvades this region. Whenever succession is obstructed, either by biotic or natural reasons, the pace is usually altered, and the process is pushed back by several stages. This is called "retrogression". It can occur due to floods, droughts, landslides or epidemic. Other factors, like clearings made by humans, felling of trees, overgrazing, shifting cultivation and forest fires also cause retrogression.
The vegetation in these areas is characterised by decreasing species diversity, loss in quality and productivity and the elimination of sensitive species. The change in species is also accompanied by a change in soil conditions. In many sal forests, the original climax forests have been destroyed by grazing or burning and have now been replaced by grasses. In the Himalayan slopes, often, the trees are felled, and afforestation becomes difficult because the soil layers are eroded, leaving only a dry, bare rock surface.