Fig. 1

Explanations for stand spatial structural parameters. Structural unit contains a reference trees i and four nearest neighbors and their spatial relationships can be described by uniform angle index (W), mingling (M) and dominance (U), respectively. In the top panels, patterns change from regularity to clump with increasing W value. In the medium panels, reference tree i has more heterospecific neighbors with increasing M value. In the bottom panels, reference tree is less dominant in structural unit with increasing U value