Land rehabilitation in arid Gobi Desert environment using native plant species

Abstract

The ability to rehabilitate disturbed lands and restore ecosystem processes is of great importance for the mine closure process as functional ecosystems maintain long-term biodiversity and ecosystem service values. The Oyu Tolgoi (OT) Mine, located in Umnugobi Aimag, southern Mongolia, is known for its production of copper (450,000 tonnes per year), making it the largest financial undertaking in Mongolia's history. Despite this, the OT mine has several challenges to overcome in order to develop processes that will assist in the rehabilitation and restoration of areas disturbed by mining development activities. The first challenge was an early commitment to using only native species, which relates to the second challenge caused by the harsh desert climate where the mine is located in. The unprecedented decision to use only native species was a challenge as little research had previously been done on how to grow native Gobi Desert plant species and use them in rehabilitation efforts. This knowledge gap led to the creation of the OT Native Plant Propagation Center (NPPC) in Khanbogd Soum, Mongolia to conduct research on the collection of seeds, propagation of plants, and preparing seeds and saplings for restoration work. By starting rehabilitation programs early (during the construction stage), OT has had time to develop and test rehabilitation methods and begin to rehabilitate areas to allow more time for plants to establish and grow. While OT is still in the construction phase, it has already gained 10 years of experience in growing native Gobi plant species and rehabilitating disturbed areas through the drill seeding and hydroseeding as well sapling planting method. In this study, the monitoring survey was conducted in 2017-2018 by comparing the three rehabilitated areas in 2013 using the above three methods and the adjacent undisturbed areas. Vegetation cover, species richness and biomass were measured at 30 m x 30 m plot which was established in each study site and similarity was analyzed. Preliminary results of comparing biologically rehabilitated areas to the control plots showed that the sapling planted area has the greatest similarity (75%) and no difference in vegetation cover and biomass (t = -0.88, p = 0.40; t = -0.22, p = 0.83) with the control. In contrast, the similarity of the hydroseeded area was 45.5%, while the drill seeded area was the least similar to the control area (0%). This suggests that the sapling planting method was the most successful rehabilitation method. However, the study will be continued to include more rehabilitated areas and allow more time for vegetation recovery in rehabilitated areas.