**2.4 Statistical analyses**

Seed density was measured as the number of germinated plants in the soil seed bank of each plot, which was then converted to a seed bank number (in 1 m<sup>2</sup> units). Species diversity of the SSB was calculated based on seed densities and species composition via the Shannon-Wiener diversity index (H), the Simpson diversity index (D), and the Pielou evenness index (E) [23–25], as follows

$$\text{Richness index}: \mathbb{R} = (\mathbb{S} - \mathbb{1}) / \ln \text{N} \tag{1}$$

$$\text{Shannon} - \text{Wiener diversity index } (\text{H}):\\H = -\sum\_{i=1}^{s} (P\_i \text{1n}P\_i) \tag{2}$$

$$\text{Simpson diversity index}: D = 1 - \sum\_{i=1}^{S} P\_i^2 \tag{3}$$

$$\text{Pielou evenness index (E)}: E = H/\text{1nS} \tag{4}$$

Where N is the total number of seeds in the SSB for each plot type, S is the total number of species in the SSB of each plot, and Pi is the number of the i-th species' seeds divided by the total number of seeds in a given plot.

The SPSS19.0 software package was used for single-factor analysis of variance (one-way ANOVA) tests of SSB differences, while the least significant difference method (LSD) was used to evaluate the statistical significance of differences. Microsoft Excel 2003 was used for graphical representations and other statistical analyses.
