## 3 Results
### Relationship between Root Morphological Indexes and Elevation of Cynodon dactylon Roots
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Location** & **Elevation Gradient** & **Average Tension/N** & **Average Tensile Strength/Mpa** & **Average Tension/\%** & **Modulus/Mpa** \\ \hline \multirow{3}{*}{Ertan} & L & 6.01 \(\pm\) 1.40 c & 54.12 \(\pm\) 15.43 b & 24.95 \(\pm\) 2.59 a & 213.72 \(\pm\) 41.89 c \\  & M & 8.59 \(\pm\) 1.99 b & 58.14 \(\pm\) 14.03 ab & 21.03 \(\pm\) 2.56 b & 274.44 \(\pm\) 45.62 b \\  & H & 12.26 \(\pm\) 2.40 a & 61.69 \(\pm\) 17.16 a & 18.39 \(\pm\) 2.11 c & 330.76 \(\pm\) 61.58 a \\ \hline \multirow{3}{*}{Guanyinyan} & L & 5.02 \(\pm\) 0.86 c & 52.92 \(\pm\) 12.13 b & 28.19 \(\pm\) 2.05 a & 186.25 \(\pm\) 32.10 c \\  & M & 6.95 \(\pm\) 1.21 b & 56.83 \(\pm\) 12.81 ab & 24.24 \(\pm\) 2.66 b & 232.56 \(\pm\) 33.61 b \\  & H & 9.63 \(\pm\) 0.83 a & 60.65 \(\pm\) 8.24 a & 21.27 \(\pm\) 1.05 c & 284.78 \(\pm\) 32.83 a \\ \hline \hline \end{tabular} Note: The data in the table are mean \(\pm\) standard deviation. The same letters indicate no significant difference between the two (\(p>\) 0.05), while different letters indicate significant difference between the two (\(p<\) 0.05).  
\end{table} 
Table 2: Relationship between mechanical properties of _Cymodon dactylIon_ roots and elevation. Figure 4: Proportion of each index to the total amount for different diameter classes of plant roots in Guanyinyan Reservoir. L, M, and H represent three elevations from low to high. (**a**): Length was used as the root structure index; (**b**): the surface area was used as the index of the root structure; (**c**): volume was used as the index of the root structure. Relationship between Ultimate Elongation and Young's Modulus of Cynodon dactyllon Plant Root and Elevation  
The relationship between the ultimate elongation of a single root and rootstocks of _Cynodon dactyllon_ roots was modeled using power functions (Figures 7 and 8). The fit (R\({}^{2}\)) was small for the relationship between ultimate elongation and diameter. However, a trend can be observed where the ultimate elongation decreased with increasing diameter. At different elevation gradients, the ultimate elongation followed the order L > M > H, and the average elongation exhibited significant variations across different elevation gradients (\(p\) < 0.05). The Young's modulus ranged from 148.43 to 454.18 MPa for Ertan _Cynodon dactyllon_ roots and 131.31 to 355.53 MPa for Guanyingyan _Cynodon dactyllon_ roots. The [PERSON]'s modulus of Ertan _Cynodon dactyllon_ roots was greater than that of Guanyingyan at all three elevation gradients. In addition, the [PERSON]'s modulus of _Cynodon dactyllon_ roots decreased as a power function with increasing diameter and increased with elevation. Figure 5: Relationship between different elevation gradients of Ertan and the tensile force and tensile strength of _Cynodon dactyllon_ (**a**): tensile resistance; (**b**) tensile strength. Figure 6: Relationship between different elevation gradients of Guanyingyan and the tensile force and tensile strength of _Cynodon dactyllon_ (**a**): tensile resistance; (**b**) tensile strength.