Surface Soil Replacement Improve Soil Quality for Nothofagus Pumilio Forest Reclamation in Chilean Southern Patagonia.

Forest reclamation of disturbed land in mining areas in Southern Patagonia is a difficult challenge.  Reclamation after coal surface mining can take many years, especially in areas where vegetation growth is limited by natural climate conditions like Chilean Southern Patagonia. Recommendations established by the forest reclamation approach include top soil removal and storage before mining and then replace it at the time of starting revegetation efforts. The objective of this study was to evaluate the effect of a reapplication of top soil on soil quality and revegetation success of Nothofagus pumilio, in comparison to undisturbed grassland. The study was conducted in Riesco island, Magallanes Region, Chile. Four different sites of 0.25 ha inside Mina Invierno compensation area were selected for the study. Surface soil was removed to a depth of 1.3 m and storage for six months before it was replaced into the same area. Four other grassland sites were selected close to the one where the soil was replaced. Following soil replacement, Nothofagus pumilio seedlings were planted in both conditions and measured for morphological and physiological parameters for two growing seasons. At the end of the second year, volunteer herbaceous vegetation was characterized and compared between the two sites. Composite soil samples were sampled and characterized for physical, chemical and biological parameters at each site as well. The results showed that soil removal and replacement creates better site conditions for reforestation in comparison to the undisturbed grassland. Seedlings growth and survival was significantly higher in the replace soil sites in comparison to the undisturbed grassland sites. Soil parameters were significantly better for water holding capacity, bulk density and penetration resistance in comparison to the grassland sites. Herbaceous composition and coverage were different between the replaced topsoil and the grassland sites as a consequence of the soil removal. Our results suggest that surface soil removal, when is properly handle, improve Nothofagus pumilio restoration efforts in Southern Patagonia in comparison to reforestation on degraded grassland.