Abstract: [Objective] This research aims at investigating the variation patterns of tree morphology with different stand densities and mingling intensities in natural scenic forest, and clarifying the effects of stand density, mingling intensity and their interaction on tree morphology of different diameter classes.[Method]65 plots were set up in typical areas of Changbai Mountain, the forest spatial structures and tree morphological indicators were investigated. By using synthetic index method, four morphology indices were established, and the effects of stand density, mingling intensity and their interaction on these indices were analyzed with variance analysis method. [Result] Stand density had very significant effects (P<0.01) on all tree morphology indices. The increase of stand density had adverse effects on tree spatial occupancy index (U₁), stem and crown coordination index (U₂) and crown expansion index (U₃), while had a beneficial effect on stem straight index (U₄). The effects of stand density on U₁ and U₂ were very significant (P<0.000 5) in all three diameter classes, while the effect on U₃ were very significant (P<0.000 5) only in middle diameter class, and the effect on U₄ were significant (P=0.017) only in small diameter class. Mingling intensity was negatively correlated with U₁, U₂ and U₄, while positively correlated with U₃. The effect of mingling intensity on U₂ were very significant (P<0.000 5), and this effect showed extremely significant difference (P<0.000 5) and significant difference (P=0.038) in small diameter class and large diameter class, respectively. The interaction had a very significant influence (P<0.000 5) on U₃, and the influence of stand density on U₂ showed a trend of increasing first and then decreasing with the increase of mingling intensity, while the influence of mingling intensity on U₂ was on the contrary.[Conclusion] In scenic forest, stand density and mingling intensity significantly affected crown, stem and their coordination by changing the competition relationship of neighboring trees, and the stand density played a major role. Within the scope of the study, the stand density of more than 1 200 individual·hm^-2 had a significant suppression on the increase of tree volume and tree morphology coordination of all three diameter classes, while mingling intensity showed a significant influence on the tree morphology coordination in large diameter and small diameter trees when the density was more than 1 600 individual·hm^-2 or less than 800 individual·hm^-2, and the forest with low density and moderate mingling intensity were most beneficial to the coordinated development of trunk and crown morphology.

Key words: scenic forest, tree morphology, crown shape, stem form, stand density, mingling intensity, diameter class