“…The total N, P, and K contents of litter were determined using the Kjeldahl determination, vanadium–molybdenum yellow colorimetry, and flame photometry, respectively, after the litter residues were digested by a H 2 SO 4 ‐H 2 O 2 mixture (Q. Li, Zhao, et al, 2016; Y. Li, Zhou, et al, 2016, Table S1). Furthermore, the contents of soluble sugars, amino acids, total organic acids, water‐soluble phenols, terpenoids, and flavones were estimated using anthrone colorimetry, ninhydrin colorimetry, potentiometric titrimetry, foline‐phenol colorimetry, vanilline‐glacial acetic acid colorimetry, and sodium nitrite‐aluminum nitrate colorimetry, respectively (Bai et al, 2021; Hua et al, 2020; Leng et al, 2016; Liang & Wang, 2021; Shi, 2017; L. Wang et al, 2021). The contents of the aforementioned metabolites were calculated using the amount of the corresponding representative substances, namely, glucose, leucine, oxalic acid, gallic acid, ursolic acid, and rutin, respectively (Table S2).…”