The highland ecosystem is formed by the extreme environmental conditions, covering the very low temperature at night, high sun radiation during the day with short photosynthetic period, thick fog, high rainfall and soil with poor nutrition. The plants that grow in this area are very special; passing the evolution to survive in an extreme living condition. A lot among those species, including local grass as well as several rhododendron species and moss, are identified as suitable in the overburden terracing reclamation. At the end of 2010, the total new disrupted land is 24 hectare. During 2010, more than 61.18 hectare disrupted land near the mining area in the highland area has passed the re-vegetation as part of a longer term reclamation program. We monitor the performance of various planting techniques and modify the programs to improve the long term success of this plant.
Until the end of 2010, more than 171 plant species were able to grow on the land containing sirsat. This includes the cover plants of the legume species for animal food; original trees such as casuarina, matoa, eucalyptus, and coconut; agricultural plants such as pineapple, melon, sugarcane, and banana; as well as vegetables and cereals such as chili, cucumber, tomato, paddy, corn, legumes, and pumpkin. Another strategy of the sirsat reclamation is by letting the occurrence of natural ecological succession (natural re-growth of original species) at the specified area. A independent research project on natural succession at the sirsat sedimentation area has discovered that within a period of only several years, more than 500 plant species were able to conduct the natural colonization and grew very well.
New land that is formed at the estuary area of the sirsat and natural sediment flow, have conducted the mangrove colonization without support. In the last several years, tens of species of mangrove, crab, shrimp, snail, oyster, fish and sea worm were identified in these mangrove colony areas. In order to speed up the primary succession process in these new formed land, PT. Freeport Indonesia has planted hundreds of thousand mangrove trees in these areas, employing contractors from the Kamoro community who are the native settlers in the lowland. The monitoring on such project showed that the growth rate and survival capacity of the planted seeds are similar to what are reported for the colonization program throughout the world, as explained in the scientific literature.