"三元剥蚀"与路南石林发育

Triplex erosion and the development of the Lunan Stone Forest

石林是一种稀有的喀斯特地貌景观,其发育演化有其独特的过程。本文提出了石林发育的"三元剥蚀"机制,通过对土下溶蚀速率、表土剥蚀速率与(石)柱顶剥蚀速率三者不同组合的分析,讨论了石林发育的方向与趋势,并对当前路南石林发育的阶段和方向进行了具体研究。研究表明,作为石林增长拔高源动力的土下溶蚀强度的影响范围是有限的,其下限约在土下10m处,而真正能促使石林快速发育的深度是在土下2m以内。在现代自然条件下,路南石林顶部的剥蚀降低速度为10.4mm/ka,土下的溶蚀加深速度为26.17 mm/ka,石林的实际高度仍以15.77mm/ka的速度在拔高;表土剥蚀速度为650mm/ka,石林的可见高度现正以639.6mm/ka的速度增加,土壤正以623.83mm/ka的速度快速变薄,表明虽然目前石林的可见高度仍在增加,但其发育的最佳时期已经过去。

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.