Bivariate correlation analysis between the appearance of the extremely small populations and the measured variables.

<p>* Significant at the 5% level of probability, ** Significant at the 1% level of probability.</p><p>The numbers from 1 to 20 represent the 20 species with extremely small populations, as shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097751#pone.0097751.s001" target="_blank">Appendix S1</a>. E1, canopy density; E2, altitude; E3, slope aspect; E5, road quality; E6, distance between population and road; E7, surrounding population density; E8, land use type.