Abstract: In the aim of exploring the underground habitat conditions for vegetation reconstruction of high and steep slopes, we investigated the habitat conditions of fractures where plants grow by measuring body fracture rate, temperature and humidity of fractures, and soil fertility in the fractures. Furthermore, we summarized the threshold of ecological geo-indicators through statistics of root mass of plants in limestone slopes by using sampling land method. The high-steep slopes of limestone in Shandong and Henan Regions were taken as research objects. Results revealed that the thresholds of ecological geo-indicators of green coating of high-steep slopes of limestone in North China include: 1) the adaptive range of body fracture rate of rock is 1.2‰~5%; 2)the root mass depth of small arbor and shrub is 20~40 cm which is the stable layer of plant species in underground habitat and the thresholds of adaptable temperature and humidity are 0～26 ℃, 90%～100%, respectively; 3) the soil also needs to meet certain fertility standards. Connected fracture network, adaptable and relatively stable temperature and humidity,given soil nutrient are important elements in the process of vegetation reconstruction of the limestone slopes,guaranteeing the stable underground habit needed for plant growth.

Key words: high-steep slope of limestone, green coating, threshold of ecological geo-indicator, condition of underground habit, body fracture rate