3.1 General dataset information
We established a SOC and TN database from different sampling depths and
corresponding to different LUCCs. A more detailed data description is
presented in Table 1. Obviously, the deeper the soil, the smaller the
sample size (number of samples collected) in our meta-analysis.
Therefore, appropriate adjustments were made: when the soil depth was
greater than 30 cm, the sample size of shrub land was greatly reduced,
so it was incorporated into the secondary forest. Similarly, when the
soil depth reached 100 cm, secondary forests, plantation and fruit trees
were collectively referred as other woodlands.