an apex existing at the end of the polygon (hereinafter referred to as end apex). When it is judged in step SP2 that no apex exists in the interior of the polygon, in step SP3, the triangle is cut from the polygon. Then, the processing in step SP1 is carried out again for the remaining apexes. On the contrary, when it is judged in step SP2 that another apex exists in the interior of the polygon, in step SP4, the polygon is divided into two divided polygons with respect to the end apex and an apex in the interior of the triangle and at the closest position with respect to the end apex. Then the series of operations are carried out for each divided polygon.
When the polygon havingSpecifically, the soil structure turned towards loose soil and the soil nutrients decreased from non-affected areas to severely affected areas, but the soil organic matter and available potassium increased slightly in the extremely affected areas. Soil saturated hydraulic conductivity showed a 1.7- to 4.1-fold increase in the lake-surrounding areas, and the highest value (401.9cmd-1) was detected in the severely affected area. Soil water-holding capacity decreased gradually during the transition from the non-affected areas to the severely affected areas, but it increased slightly in the extremely affected areas. The principal component analysis showed that the plant biomass was vital to the changes in soil hydrological properties. Thus, the vegetation might serve as a link between the thermokarst lake and soil hydrological properties. In this particular case, it was concluded