## 3 Results
### Evolution Characteristics of the ESV in Different Landform Types
#### 3.2.2 ESV Terrain Effect in Different Landform Areas  
Elevation Effects of the ESV Changes  
With the increase in elevation, the total ESV of the three landform type areas over the past 35 years showed the trend of first increasing and then decreasing (Figure 6), and the change over time was small. The maximum ESV in the pure-karst and semi-karst areas was between 800 and 1100 m, accounting for 30% and 31% of the total ESV, respectively, and the minimum was within 500 m, accounting for less than 5%. The maximum ESV in non-karst areas was between 500 m and 800 m, accounting for 31.42-32.18% in the 35 year period, and the minimum was  
Figure 6: Elevation effect of the ESV in different landform areas from 1985 to 2020. Note: (**a**,**c**,**c**) in the figure represents the total ESV of the pure-karst, the semi-karst, and the non-karst areas, respectively, in each elevation gradient. (**b**,**d**,**f**) represents the ESV per unit area of the pure-karst, the semi-karst, and the non-karst areas, respectively, in each elevation gradient. between 1400 m and 1700 m, accounting for approximately 7%. When the elevation was above 800 m, the total ESV of the non-karst area decreased rapidly, below that of the pure-karst area by approximately 50%; however, it was always higher than that of the semi-karst area. This is mainly related to the topography of Guizhou Province, which is high in the west and low in the east. Non-karst areas are mostly distributed in areas with an elevation lower than 800 m at the edge of Guizhou Province such as Qiandongnan Prefecture and Chishui City (the forest in non-karst area accounts for approximately 11.40% of the total area of the province), while pure-karst and non-karst areas are mainly on the plateau above 800 m. In addition, within the elevation of 1100 m to 1400 m, although the order of the total size of the areas was as follows: pure-karst \(>\) semi-karst \(>\) non-karst, the pure-karst area was dominated by cropland and forest, which accounted for 50% and 46% of the area of cropland and forest in the pure-karst area, and the non-karst area was dominated by forest and shrubland, which accounted for 32% and 18% of the non-karst area, respectively. In the semi-karst area, cropland is dominant, accounting for approximately 34% of the cropland area in each period, while the forest area only accounted for approximately 21%. The contribution of the ESV of cropland was less than that of the forest area, resulting in the non-karst area being smaller than that of the semi-karst area, but its ESV was larger than that of the semi-karst area. In terms of the elevation gradient of the ESV per unit area in the three landform types, the change trend in the ESV per unit area in the three landform types generally showed a first increasing, then decreasing trend, and the transition zone of the maximum and minimum was the same as that of the total ESV. However, when the elevation was above 1100 m, the area of cropland, forest, shrubland, and grassland in the non-karst area increased to different degrees with the elevation, which made the ESV in the non-karst area increase, and the ESV per unit area increased accordingly. In contrast, the area of cropland and forest in the semi-karst area and pure-karst area gradually decreased with the elevation increase, and the total ESV in the semi-karst area and pure-karst area decreased. Slope Effect of the ESV Change  
It can be seen from Figure 7 that the ESV in the non-karst area varied significantly with the slope, showing a law of first increasing and then decreasing with an inverted V-shaped trend. This was followed by the semi-karst area, and the pure-karst area had less variation. The ESV of the three landform type areas in different slope ranges showed relatively little change over time. The maximum ESV in the non-karst and semi-karst areas was in the range of 15\({}^{\circ}\) to 25\({}^{\circ}\), accounting for approximately 37% and 34% of the total ESV of this landform-type area.