## 3 Results
### Significance of Changes following the Tests  
The data characterizing the samples of the delimited soil layers largely failed the normality tests, as shown in Tables A2-A4. For that reason, it was not possible to use parametric comparison tests, and the Mann-Whitney test was used given the type of data used. Figure 5 shows the results of the statistical comparison for the H testing area along with the main descriptive statistics of the datasets used for comparison. Figure 5a, for instance, shows the size effects found by the comparison tests as the main statistic for comparison, along with the significance of the tests given by a traffic light color code of the labels of the data. The same logic was kept for the graphical representation of the results in the case of F (Figure 6) and S (Figure 7) testing areas. Figure 5: Results of the comparison tests and the main descriptive statistics of the H datasets: (**a**) results of the comparison tests taking as a reference the control data on soil layer depths; (**b**) main descriptive statistics of the datasets used for comparison. Note: in panel (**a**) the effect size is indicated in the data labels along with three types of text formatting and a traffic light color coding in whichthe normal text indicates no difference, text given in italics indicates a significant difference, text given in bold italics indicates a significant difference where the median values estimated based on control were lower than those of the compared data, green indicates no differences, yellow indicates higher median values in control data and red indicates higher median values in the compared data; in panel (**b**) red dots stand for the outlier values found by the statistical software used. Legend: C--control, H--horse logging, P1 to P15--pass 1 to pass 15. Figure 6: Results of the comparison tests and the main descriptive statistics of the S datasets: (**a**) results of the comparison tests taking as a reference the control data on soil layer depths; (**b**) main descriptive statistics of the datasets used for comparison. Note: in panel (**a**) the effect size is indicated in the data labels along with three types of text formatting and a traffic light color coding in which the normal text indicates no difference, text given in italics indicates a significant difference, text given in bold italics indicates a significant difference where the median values estimated based on control were lower than those of the compared data, green indicates no differences, yellow indicates higher median values in control data and red indicates higher median values in the compared data; in panel (**b**) red dots stand for the outlier values found by the statistical software used. Legend: C--control, S--skidding, P1 to P15—pass 1 to pass 15. The first pass (P1) with horses produced no statistically significant changes in the first 20 cm of the soil and, in the rest of the profile, there were statistically significant changes but in the sense of a decreased penetration resistance compared to the control data (soil loosening). The second pass produced rather low effects but significant changes in the increment of penetration resistance in the first 20 cm of the soil, although their magnitude in difference was low (Figure 5b). The trend was preserved for the third pass, where the first 20 cm of soil was affected by an increased penetration resistance; in this case, the effect size approached a moderate figure  
Figure 7: Results of the comparison tests and the main descriptive statistics of the F datasets: (**a**) results of the comparison tests taking as a reference the control data on soil layer depths; (**b**) main descriptive statistics of the datasets used for comparison.