Triplex erosion and the development of the Lunan Stone Forest
"三元剥蚀"与路南石林发育

Stone forest is a kind of rarely-seen karst landscape, which has its own unique e-volution process. Based on the analysis of stone pillar-the individual component of stone forest, this paper, by discussing different combinations of the rates of edaphic corrosion, soil erosion and aerial erosion, puts forward the model of "triplex erosion" to explain the development of stone forest and studies the current development stage and evolutional prospect of the Lunan Stone Forest. The research reveals that the scope of edaphic corrosion, which is the basic driving force for the heightening of stone pillars, is limited within about 10 m below ground surface, and the depth best for the development of stone forest is observed to be usually less than 1.5m under the current natural conditions in the area. Since the top of stone pillars is lowering at a rate of 10. 4 mm/ka, and the bottom deepening 26. 17 mm/ka, therefore, the actual height increase of stone pillars is 15. 77 mm/ka; considering that the soil erosion rate in the area of Lunan Stone Forest is 650 mm/ka, the visible height of stone forest is increasing at a rate of 639. 6 mm/ka, and soil, an extremely significant factor for the heightening of stone pillars, is rapidly becoming thinner and thinner at a rate of 623. 83 mm/ka. All this shows that the best time for the development of Lunan Stone Forest has gone, though the visible height of stone forest is still increasing at present. The study result of the paper attaches great importance to the reduction of soil erosion in Shilin area. Therefore, it is necessary for the local people to take effective measures to prevent soil from being rapid eroded, especially, considering the stone forest in Lunan area a precious natural heritage owned by all human beings as well as local people.