## 4 Results
### Accumulation of REE in the Roots of Scutellaria bialensis  
The biological absorption coefficient (BAC) of REEs provides an estimate of the individual availability of REEs to the plant [26; 27; 28]. This was adopted to quantify the natural process of element transfer from the soil to the roots of _Scutellaria bialensis_. The BAC is defined as follows (3):  
\[\mathrm{BAC_{i}}=\frac{\mathrm{CM_{i}}}{\mathrm{CS_{i}}}, \tag{3}\]  
where BAC\({}_{i}\) is the migration and accumulation rate of element i, and CM\({}_{i}\) and CS\({}_{i}\) are the concentrations of element i in the plant and soil, respectively. The results were categorized into five groups based on the magnitude of the coefficient: BAC \(>\) 3--very strongly accumulated; from 1.5 to 3.0--strongly accumulated; from 0.5 to 1.5--moderate absorption; from 0.1 to 0.5--weak absorption, and BAC \(<\) 0.1--very weak absorption [29]. Under normal circumstances, the ratio of the concentrations of REEs in plants to that in the soil is less than 1, even as low as 0.02 [30]. In the study area, all REEs in _Scutellaria bialensis_ had low BACs: less than 0.1. One-way ANOVA and LSD tests were applied to analyze whether there were remarkable differences in the BACs of REEs between various habitats after the test for normal distribution and homogeneity of variance. In addition, permutation tests, t tests and nonparametric tests were utilized for the BACs that were not normally distributed or had heterogeneity of variance. The statistical analyses were conducted in the R program. In the box plots, various letters (e.g., a and b) imply that there exist statistically remarkable differences between BACs in various habitats (\(p<0.05\)); otherwise, differences are not statistically remarkable(e.g., ab and a, ab and b). Almost all HREEs and Y, except for Gd and \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multirow{2}{*}{**Habitats**} & \multicolumn{2}{c}{**Median (25–75\%)**} & \multirow{2}{*}{**Average (mg-kg\({}^{-1}\))**} & \multirow{2}{*}{**Skewness**} & \multirow{2}{*}{**CV/\%**} & \multirow{2}{*}{\(p\) Value**} \\  & & & **(mg-kg\({}^{-1}\))** & & & & \\ \hline \multirow{3}{*}{\(\Sigma\)REE} & NGHs (\(n=11\)) & 2.02 (1.79–2.3) & 2.21 & 1.14 & 47.0 & 0.066 \\  & APHs (\(n=10\)) & 1.78 (1.55–2.31) & 1.94 & 1.01 & 30.3 & 0.484 \\  & BCHs (\(n=8\)) & 2.04 (1.5–3.33) & 2.34 & 0.386 & 38.0 & 0.042 \\ \hline \multirow{3}{*}{\(\Sigma\)LREE} & NGHs (\(n=11\)) & 1.78 (1.62–2.11) & 2.00 & 1.24 & 49.2 & 0.056 \\  & APHs (\(n=10\)) & 1.6 (1.4–2.09) & 1.76 & 0.998 & 30.7 & 0.491 \\  & BCHs (\(n=8\)) & 1.82 (1.36–3.12) & 2.15 & 0.441 & 39.8 & 0.039 \\ \hline \multirow{3}{*}{\(\Sigma\)HREE} & NGHs (\(n=11\)) & 0.212 (0.175–0.246) & 0.209 & \(-0.541\) & 30.3 & 0.724 \\  & APHs (\(n=10\)) & 0.187 (0.146–0.217) & 0.187 & 1.07 & 28.1 & 0.376 \\  & BCHs (\(n=8\)) & 0.183 (0.148–0.235) & 0.189 & 0.378 & 25.7 & 0.580 \\ \hline \multirow{3}{*}{LREE\(\backslash\)HREE} & NGHs (\(n=11\)) & 8.64 (7.55–10.8) & 9.27 & 1.48 & 23.7 & 0.063 \\  & APHs (\(n=10\)) & 9.27 (8.57–9.89) & 9.38 & 0.840 & 11.0 & 0.536 \\  & BCHs (\(n=8\)) & 10.2 (9.13–14.7) & 11.27 & 0.556 & 26.2 & 0.283 \\ \hline \multirow{3}{*}{\(\mathrm{La}_{N}\backslash\mathrm{Yb}_{N}\)} & NGHs (\(n=11\)) & 15.2(12.4–20.9) & 17.26 & 1.07 & 43.4 & 0.291 \\  & APHs (\(n=10\)) & 16 (14.6–18.4) & 16.56 & 1.04 & 15.0 & 0.246 \\  & BCHs (\(n=8\)) & 19.8 (16.5–32.9) & 24.58 & 1.10 & 43.6 & 0.168 \\ \hline \multirow{3}{*}{\(\delta\)Eu} & NGHs (\(n=11\)) & 1.28 (1.08–1.57) & 1.32 & \(-0.109\) & 22.8 & 0.985 \\  & APHs (\(n=10\)) & 0.937 (0.854–1.14) & 0.998 & 0.787 & 16.0 & 0.185 \\  & BCHs (\(n=8\)) & 1.06 (0.972–1.13) & 1.05 & \(-0.357\) & 11.6 & 0.972 \\ \hline \multirow{3}{*}{\(\delta\)Ce} & NGHs (\(n=11\)) & 0.9 (0.730–0.950) & 0.845 & \(-1.00\) & 15.7 & 0.192 \\  & APHs (\(n=10\)) & 0.935 (0.858–0.963) & 0.897 & \(-1.55\) & 12.5 & 0.009 \\ \cline{1-1}  & BCHs (\(n=8\)) & 0.935 (0.835–1.04) & 0.933 & \(-0.241\) & 16.7 & 0.933 \\ \hline \hline \end{tabular}
\end{table}