Fig. 3

Semi-matrix graph of interspecific correction χ² test of association of dominant tree populations in an old-growth oak broad-leaved mixed forest in the Qinling Mountains, China. a is development stage of juvenile tree (5 cm ≤ DBH < 10 cm); b is development stage of medium tree (10 cm ≤ DBH < 25 cm); c is development stage of large tree (DBH ≥ 25 cm); and d is total forest (DBH ≥ 5 cm). When χ² ≥ 6.635, extra significant positive association; 3.841 ≤ χ² < 6.635, significant positive association; −3.841 ≤ χ² < 3.841, no association, independent distribution; −6.635 ≤ χ² < −3.841, significant negative association; χ² < −6.635, Extra significant negative association. See above for abbreviations